Rafter system for a pitched roof: use a calculator to calculate the truss system. Shed roof: necessary calculations Shed roof 6 by 8 meters

For small buildings, for example, a barn or garage, often use a pitched roof. Simple in design, it can be easily manufactured without the involvement of professional builders and looks very attractive. For the arrangement of residential buildings, such a solution is used less often: often the power of tradition and the little experience in its design and construction for our area work. The time has come to evaluate the advantages of such a design.

Features: pros and cons

A pitched roof is a rectangular, absolutely flat shape located at an angle relative to the building frame. The magnitude of its inclination may vary depending on the architectural design, climatic conditions and the surrounding landscape. Using quality materials, lasts at least 20–30 years.

This type of roofing device is considered the most stable, including to external natural influences, if the location of the building is unmistakable in relation to the wind rose.

The snow falls on the surface in an even layer, which makes the load uniform and safe.

The sloping lean-to form is better than the gable form, although it does not allow for the creation of a comfortable attic space. But it’s easier with a ventilation system: aerators and a ventilated ridge are simply not needed.

The benefits also include:

• Low load on supporting structures due to relatively low weight.
• Lowest consumption of building materials compared to other types of roofs.
• Modest financial costs.
• Simple and quick way construction that can be done with your own hands.
• There are no restrictions in the choice of roofing materials and rafter system.
• Affordable planning and installation of drainage and chimney systems.

Harmonious beautiful project requires compliance with many conditions, sometimes to the detriment of functional needs.

There are fewer disadvantages than advantages, but still they exist.

• To arrange the living space of the attic, a significant width of the house and a high roof angle are required.
• A low bevel can cause poor thermal insulation.
• A reinforced drainage structure with a wider pipe diameter is required, since all the water flows in one direction. Metal systems with brackets secured at a distance of at least 40 cm are recommended.
• If the slope is less than 45 degrees, in winter you will have to constantly clear the roof of snow to reduce the load.

Roofing device

Like the structure of any roof, high-quality composition elements of a single-pitch depends on the finishing coating. The number of basic elements is small, but requires attention.

Armopoyas

Reduces the bursting load of the rafters and promotes uniform distribution of the weight of the entire structure. Mandatory for buildings made of aerated concrete, expanded clay concrete and brick walls, if construction is carried out in an earthquake-prone region.

Mauerlat

It is located on the upper parts of the walls in the form of beams. It is connected to an armored belt or, in the case of a brick building, secured through anchors already hammered or walled up in the walls with strong wire - at least 6 mm in diameter. The anchors themselves should be located at a distance of 30 cm from the end of the wall. If the house is wooden, made of double mini-beams, then the top frame plays the role of the Mauerlat

Gable

Rarely found in the construction of pitched roofs. Its presence is determined depending on the difference in height between the two load-bearing walls.

Rafter system

It serves as the basis for laying the roof; the main load is placed on it. It is important to ensure that it is distributed evenly along the perimeter of the upper part of the entire building, and that the pressure on the nodes does not exceed permissible values. To create it, wooden beams are used, the cross-section of which depends on the area of ​​the roof and the number of support elements.

Supports

They are selected after calculating the weight of the structure and determining the finishing coating. The quantity is determined by the angle of inclination and the length of the span.

Lathing

It is necessary for laying and securing the roofing covering and increasing the load-bearing capacity so that the frame can withstand its own weight and withstand additional loads: snow, the weight of a person during repair work.

For bitumen shingles, a continuous sheathing is performed. For these purposes, boards are used - edged or unedged; MDF panels can be used. The slope can protrude beyond the boundaries of the pediment, forming a canopy for the veranda or terrace.

Insulation

Provides protection against moisture and freezing. It is laid from the attic side between the rafters and secured to the sheathing.

Insulation

It consists of rolled tile materials that are laid on the inside of the sheathing.

Vapor barrier

Film coverings that are laid on top of the insulation and secured with a construction stapler.

Skate bar

Serves as protection for the top edge of the roof, preventing moisture from entering and rotting the internal elements of the pie.

Fasteners

Rigel

Type of horizontal support for elements of load-bearing structures. The element distributes the load of the rafters between other beams.

Spacers

Supports that are placed in the spans and increase the stability of the entire frame.

Struts

Kinds

Single-pitch structures are popular in many countries and are used in the construction of both budget and ultra-fashionable luxury housing. With a high roof slope, by abandoning the attic space, it is possible to optimize the layout. When low, there will be an increase in the volume of residential premises.

A flat roof is often paired with other types, as an element of a multi-level system. This is an excellent addition for sloping, semicircular and other types of roofs with different slopes.

The two-level versions of the “single-pitch” look beautiful with different angles tilt directed in opposite directions. Simple designs can be decorated with canopies that serve as part of a veranda or protruding attic.

Based on the type of ventilation, there are 2 types:

• ventilated - bevel from 5 to 20 degrees, holes are located in the crank wall;
• non-ventilated roofs - slope angle from 3 to 6.

Rafter system

The creation of a project and the construction of a system depends on the scale of the construction and is determined by:

• climate zone and wind rose;
• linear dimensions of the base - affects the number of rafter legs, the number of additional supports and the distance between them;
• angle of inclination - determines the presence of a pediment and the method of attachment to the supports;
• type of roofing material - dictates the choice of characteristics of the building material and the structure of the sheathing.

The pitch of the rafters also depends on their length and cross-section:

• with a length of 3 m, pitch - from 1100 to 2150 mm, cross-section - from 80 x 100 to 90 x 160 mm;
• at 6.5 m, distance - from 1100 to 1400 mm, cross section - at least 120 x 220 mm.

Often for large buildings a beam longer than 7–8 m is needed. To build it up, it is sewn together, and the joints are reinforced and fastened with planks or metal plates. The larger the rafter elements, the smaller the distance between them.

To ensure structural rigidity, the following are provided:

• racks, crossbars and struts with minimum cross-section– 50 x 100 mm;
• beds and spacers made of timber - 100 x 150 mm.

Classification of systems by width:

• Up to 4.5 meters. The simplest unsupported structures - the roof is fixed on a mauerlat made of two logs or boards, which are fixed to the walls.
• From 4.5 to 6 m. The structure is strengthened:
  • lying down - at the height of the ceiling;
  • rafter leg - it serves as a support for the beam in the center of the base; the slope of the leg is determined by the width of the house and the height of the floor above the ceiling.

• From 6 to 9 m. There are two struts that are installed on both sides of the rafter leg.
• From 9 to 12 m. Another support is definitely needed, which can be part of the protruding interior wall or an additional cantilever-girder structure, which is supported by struts.
• More than 12 meters. The number of rafter legs increases significantly. Increasing the roof overhangs to the end leads to building up the beams at the edges special elements- fillies. Fastening is done with overlays - at least 60 cm, which are fixed with bolts or nails, sometimes with mounting plates.

In addition, rafter systems are distinguished by the type of supports.

Naslonny

The system of racks and struts rests on the mauerlat beam, which is fixed on the external walls, and in some cases on the inside. The distance between the rafters is from 600 to 1400 mm. The value depends on the weight of the roofing and the characteristics of the wood. Such simple designs are available for roof slopes of up to 26 degrees and a span of up to 5 m. Most often used for outbuildings: sheds, workshops, garages.

For roofs in use, that is, the angle of inclination of which tends to zero, the rafter legs rest:

• on one side - onto a higher load-bearing wall;
• on the other - to the Mauerlat.

Hanging rafters

Used when it is impossible to install additional supports between the side posts. In this case, structures of any size are assembled on the ground or in a workshop, and ready-made trusses are gradually delivered to the construction site.

Possible materials:

• metal;
• reinforced concrete;
• wood (pine), cross-section for rafters – 50 x 150 mm, for sheathing – 50 x 50 mm.

Sliding systems

Necessary for arranging roofs in buildings with significant shrinkage during the first time after construction. These include houses built from timber or logs - uneven subsidence of up to 10%. For wooden structures, the method of attaching the rafter legs is also very important.

The principles of the device are easy to understand:

• The rafters are installed on the ridge log.
• The legs can be connected end-to-end or overlapped (with nails, bolts and steel plates).

• The pitch and selection of wood thickness for the rafters is determined by the weight of the roofing. With a top layer thickness of 50 mm, select edged board 200 mm wide.
• The attachment to the Mauerlat is special - slightly loose, without rigidity. This provides a kind of sliding, which avoids deformation of the roof during shrinkage and reduces the bursting load of the walls. Special steel brackets, 2 mm thick, with an angle are used as fasteners.

Tilt angle

The larger the angle, the higher the windage. Therefore, the roof slope should always be directed towards the most frequent winds. This reduces the load during a major storm. It is important to take into account the climate zone when making calculations.

A slight slope can cause large amounts of snow to accumulate. If you do not remove it in time and wait for ice to form, the roof under its significant weight will, at best, bend, and at worst, break.

Natural precipitation along the roof is an equally important reason when taking into account the surface and strength of covering materials. Rough types are better suited for arid regions, smooth ones for places famous for heavy rains and snowy winters.

Optimal values ​​for tiles:

• metal, ceramic and cement-sand - at least 6 degrees;
• bitumen - no less than 12.

Limit values ​​for sheet roofing:

• slate, corrugated board, ondulin - at least 6 degrees;
• copper, galvanized sheets (zinc-titanium) – from 17;
• asbestos cement slabs – from 27.

When choosing roofing materials, it is worth double-checking the information. Sometimes the declared slope values ​​for the coating specified by the manufacturer do not coincide with GOST. It is better to entrust the calculation itself to professionals, because there are many nuances, especially for large buildings.

After determining the magnitude of the slope, one of the load-bearing walls is brought to a level that will ensure the implementation of the project.

The necessary calculations to determine the length of the rafters without taking into account overhangs are made according to the rules of a right triangle.

To ensure water drainage and protect the walls from getting wet, the roof is extended an average of 600 mm. For technical buildings, the minimum for overhang is 20–25, for two-story residential cottages and mansions – up to 1200 mm.

The aesthetics of the entire building are also important. To determine your own preferences, before creating a project, you can use computer programs. This will allow you to see not only the entire roof, but also its harmonious combination with the house.

Materials

The quality of building materials determines the strength and durability of the entire building, so roofing coverings should be chosen carefully, taking into account the characteristics of both the building frame and the possibilities of the future rafter system.

Tree

For the frame, grade 1-3 wood is selected with a frequency of knots per meter of no more than 3, and their height should not exceed 3 cm. Cracks may be present, but shallow and of short length - not exceeding half the length of the board.

1. The supporting beams must have a thickness of 50 mm or more.
2. Board length:
   • from coniferous species– up to 650 mm;
   • from deciduous – up to 450 mm.
3. Additional elements - purlins, Mauerlat, pillows - are made only from hard hardwood and treated with an antiseptic.

Roof

The modern range of roof coverings is very diverse, so it’s easy to choose suitable material by color, shape, required strength and price.

Ceramic tiles

The material can be of different types: flat tape, groove, single- or double-wave. Well suited for roof angles from 25 to 60 degrees for houses made of stone, brick or wood. With smaller bevel values, it is necessary to increase ventilation and waterproofing; with larger values, it will be necessary to further strengthen the units and install additional fasteners, because tiles are a very heavy material.

The weight of one fragment of 30 x 30 cm can vary from 2 to 4.5 kg, that is, 1 m2 can weigh 50 kg. For comparison, metal tiles weigh 10 times less - 5 kg/m2. Therefore, the pitch of rafters for ceramics requires a minimum and wooden lathing with small cells. But the tiles have excellent sound insulation, beautiful color and texture. The strength of one element is small, but the service life of the entire roof exceeds the average human lifespan and reaches 150 years.

Metal tiles

These are corrugated galvanized steel sheets, which have a polymer coating on the outside. The number of protective layers, as well as the method of fastening the elements together, varies depending on the manufacturer. They come in both glossy and matte. Various sizes, thickness - from 0.4 mm, weight of 1 m2 - from 3 to 5 kg.

Assembly is carried out on the lathing, fastening with nails or self-tapping screws, overlap - in one wave. Recommended tilt: 15 degrees. If it does not exceed 20, then precipitation may drain too slowly, so the joints of the decking are additionally sealed.

Overall, metal roofing is quite strong and durable. The warranty period is from 5 to 15 years, but the wear of the polymer layer is not always taken into account. The only disadvantages are poor sound insulation and a large amount of waste.

Soft tiles

It is also called bitumen. The material is based on polyester, fiberglass and cellulose. They are applied to bitumen elements and covered with a dye on top. A special feature is adhesion, gluing of elements under the influence of sunlight. Available in the form of rectangles or semicircular sheets. The service life is determined by manufacturers to be within 15–20 years, without taking into account color fastness.

Options:

• length – 100 mm;
• width – from 300 mm;
• weight per 1 m2 – 8–12 kg.

A versatile material with good insulation, it is equally suitable for residential and commercial buildings. The recommended tilt angle is from 12 degrees. The technology provides a waterproofing substrate or lining layer. The role of such a carpet can be played by an old bitumen coating. Disadvantages include flammability, instability to ultraviolet radiation and installation only in the warm season.

Corrugated sheet

Available in the form of corrugated galvanized steel sheets of various sizes. The waves provide rigidity and strength to the coating; their height and shape depend on the specific model. There are trapezoidal, sinusoidal or rounded.

Some manufacturers outside covered with a durable polymer film.

To ensure waterproofing, a glassine gasket is used during installation. Fastening to the sheathing is carried out with self-tapping screws, the joints are treated with a bitumen compound. The recommended slope of a roof with corrugated sheeting is from 10 degrees.

Like all metal roofs, the material has little sound insulation, so it is more often used for industrial facilities and sheds. The warranty period is 15–20 years.

Ondulin

Universal covering material, which can even be used for cladding a house. It is based on cellulose, which is impregnated with purified bitumen with the addition of resins and pigments. The color is permanent. Standard sheet dimensions are 2000 x 950 mm, weight is 6.5 kg/m2, which is 4 times lighter than traditional slate.

Positive properties include:

• ease;
• strength;
• moisture resistance;
• excellent sound insulation;
• high resistance to temperature changes;
• immunity to chemical reagents.

Although the minimum acceptable level of slope is 6 degrees, ondulin is not recommended for use on roofs with a slight slope: there is no way to hold long time snow. With higher values ​​and proper operation, the service life will be about half a century, the waterproofness guarantee is 15 years.

Slate

Corrugated sheets made of a composite material based on Portland cement and asbestos fiber. The shape of the corrugated sheet is always rectangular - 120 x 70 mm, weight - from 10 to 15 kg/m2. The roof slope level is from 12 to 60 degrees. The installation technology requires a lining layer of roofing material or glassine.

The slate is attached to the sheathing with an overlap using nails through soft sealed gaskets.

The timber for the frame is selected:

• for a standard sheet - 50 x 50 mm, rafter pitch - from 500 to 550 mm;
• for reinforced - 75 x 75 mm, step length - from 750 to 800 mm.

Ruberoid

One of the popular budget options. It is roofing cardboard impregnated and coated with bitumen. To avoid sticking, a coarse powder is applied to the top.

The modern variety is euroroofing felt, which consists of fiberglass or polyester impregnated with bitumen. There is a polymer layer on top. This elastic and waterproof material is often covered small areas roofs with complex shapes. The main disadvantage is its rapid flammability, so complete installation can only be carried out at technical facilities.

• Canopies are classified as the most simple structures, which are erected on a suburban or summer cottage site. They are used for a variety of purposes: as a parking lot, storage area and many other options.

  Structurally, the canopy is extremely simple. This

  • frame, the main element of which is trusses for canopies, which are responsible for the stability and strength of the structure;
  • coating. It is made of slate, polycarbonate, glass or corrugated sheet;
  • additional elements. As a rule, these are decoration elements that are located inside the structure.

  The design is quite simple, and it also weighs little, so you can assemble it with your own hands right on the site.

  However, in order to get a practical, correct canopy, you first need to ensure its strength and long-term operation. To do this, you should know how to calculate a truss for a canopy, make it yourself and weld it or buy ready-made ones.

  Metal trusses for canopies

  

  This design consists of two belts. The upper and lower chords are connected through braces and vertical posts. It is able to withstand significant loads. One such product, weighing from 50–100 kg, can replace metal beams three times larger in weight. With proper calculation, the metal truss in, channels or does not deform or bend when exposed to loads.

  The metal frame experiences several loads at the same time, which is why it is so important to know how to calculate a metal truss in order to accurately find the equilibrium points. This is the only way the structure can withstand even very high impacts.

  How to choose material and cook them correctly

  

  Creation and self installation canopies are possible with small dimensions of the structure. Trusses for canopies, depending on the configuration of the belts, can be made of profiles or steel angles. For relatively small structures, it is recommended to choose profile pipes.

  Such a solution has a number of advantages:

  • Load bearing capacity profile pipe directly related to its thickness. Most often, to assemble the frame, they use material with a square of 30-50x30-50 mm in cross-section, and for structures small size Pipes of a smaller cross-section are also suitable.
  • Metal pipes are characterized by greater strength and yet they weigh much less than a solid metal bar.
  • Pipes are bent - a quality necessary when creating curved structures, for example, arched or domed.
  • The price of trusses for sheds is relatively small, so buying them will not be difficult.

  On a note

  The metal frame will last much longer if it is protected from corrosion: treated with a primer and painted.

  • On such a metal frame you can conveniently and quite simply lay almost any sheathing and roofing.

  Methods for connecting profiles

  How to weld a canopy

  Among the main advantages of profile pipes, the non-shaped connection should be noted. Thanks to this technology, a truss for spans not exceeding 30 meters is structurally simple and relatively inexpensive. If its upper belt is sufficiently rigid, then the roofing material can be supported directly on it.

  The formless welded joint has a number of advantages:

  • The weight of the product is significantly reduced. For comparison, we note that riveted structures weigh 20%, and bolted structures weigh 25% more.
  • Reduces labor and manufacturing costs.
  • welding cost is low. Moreover, the process can be automated if you use devices that allow uninterrupted feeding of welded wire.
  • the resulting seam and the attached parts are equally strong.

  One of the disadvantages is the need to have experience in welding.

  Bolt-on mounting

  Bolted connections of profile pipes are not used very rarely. It is mainly used for collapsible structures.

  The main advantages of this type of connection include:

  • Simple assembly;
  • No need for additional equipment;
  • Possible dismantling.

  But at the same time:

  • The weight of the product increases.
  • Additional fasteners will be required.
  • Bolted connections are less strong and reliable than welded ones.

  

  How to calculate a metal truss for a canopy made from a profile pipe

  

  The structures being erected must be rigid and strong enough to withstand various loads, therefore, before installing them, it is necessary to calculate a truss from a profile pipe for a canopy and draw up a drawing.

  When calculating, as a rule, they resort to the help of specialized programs taking into account the requirements of SNiP (“Loads, impacts”, “Steel structures”). You can calculate a metal truss online using the metal profile canopy calculator. If you have the appropriate engineering knowledge, you can carry out the calculation yourself.

  On a note

  If the main design parameters are known, you can search for a suitable ready-made project among those posted on the Internet.

  

  Design work is carried out on the basis of the following initial:

  • Drawing. The configuration of the frame belts depends on the type of roof: single or gable, hip or arched. The simplest solution can be considered a single-pitched truss made from a profile pipe.
  • Design dimensions. The larger the trusses are installed, the greater the load they can withstand. The angle of inclination is also important: the greater it is, the easier it will be to remove snow from the roof. For the calculation, you will need data on the extreme points of the slope and their distance from each other.
  • Dimensions of roofing material elements. They play a crucial role in determining the pitch of the trusses for a canopy, say. By the way, this is the most popular coating for structures built on their own plots. They bend easily, so they are suitable for constructing curved coverings, for example, arched ones. All that matters is how to do it right calculate a polycarbonate canopy.

  The calculation of a metal truss from a profile pipe for a canopy is performed in a certain sequence:

  • determine the span corresponding to the technical specifications;
  • to calculate the height of the structure, substitute the span dimensions according to the presented drawing;
  • set the slope. According to the optimal shape of the roof of the structure, the contours of the belts are determined.

  On a note

  The maximum possible pitch of trusses for a canopy when using a profile pipe is 175 cm.

  How to make a polycarbonate truss

  

  The first stage of making trusses from a profile pipe for a canopy with your own hands is to draw up a detailed plan, which should indicate the exact dimensions of each element. In addition, it is advisable to prepare an additional drawing of structurally complex parts.

  As you can see, before you make trusses yourself, you need to be well prepared. Let us note once again that while the choice of product shape is guided by aesthetic considerations, a calculation path is required to determine the structural type and number of constituent elements. When testing for strength metal structure It is also necessary to take into account data on atmospheric loads in a given region.

  The arc is considered an extremely simplified variation of the truss. This is one profiled pipe with a round or square cross-section.

  Obviously, this is not only the simplest solution, it is also cheaper. However, polycarbonate canopy poles have certain disadvantages. In particular, this concerns their reliability.

  

  arched canopies photos

  Let's analyze how the load is distributed in each of these options. The design of the truss ensures uniform distribution of the load, that is, the force acting on the supports will be directed, one might say, strictly downward. This means that the support pillars perfectly resist compression forces, that is, they can withstand the additional pressure of the snow cover.

  The arches do not have such rigidity and are not able to distribute the load. To compensate for this kind of impact, they begin to unbend. The result is a force placed on the supports at the top. If we take into account that it is applied to the center and directed horizontally, then the slightest error in calculating the base of the pillars will, at the very least, cause their irreversible deformation.

  An example of calculating a metal truss from a profile pipe

  The calculation of such a product assumes:

  • determination of the exact height (H) and length (L) of the metal structure. The latter value must exactly correspond to the span length, that is, the distance overlapping the structure. As for the height, it depends on the designed angle and contour features.

  In triangular metal structures, the height is 1/5 or ¼ of the length, for other types with straight belts, for example, parallel or polygonal - 1/8.

  • The angle of the grid braces ranges from 35–50°. On average it is 45°.
  • It is important to determine the optimal distance from one node to another. Usually the required gap coincides with the width of the panel. For structures with a span length of more than 30 m, it is necessary to additionally calculate the construction lift. In the process of solving the problem, you can obtain the exact load on the metal structure and select the correct parameters for the profile pipes.

  

  As an example, consider the calculation of trusses for a standard 4x6 m lean-to structure.

  The design uses a 3 by 3 cm profile, the walls of which are 1.2 mm thick.

  The lower belt of the product has a length of 3.1 m, and the upper one – 3.90 m. Between them, vertical posts made of the same profile pipe are installed. The largest of them has a height of 0.60 m. The rest are cut out in descending order. You can limit yourself to three racks, placing them from the beginning of the high slope.

  

  The areas that are formed in this case are strengthened by installing diagonal lintels. The latter are made of a thinner profile. For example, a pipe with a cross section of 20 by 20 mm is suitable for these purposes. At the point where the belts meet, stands are not needed. On one product you can limit yourself to seven braces.

  Five similar structures are used per 6 m length of the canopy. They are laid in increments of 1.5 m, connected by additional transverse jumpers made from a profile with a section of 20 by 20 mm. They are fixed to the upper chord, arranged in increments of 0.5 m. The polycarbonate panels are attached directly to these jumpers.

  Calculation of an arched truss

  

  The manufacture of arched trusses also requires precise calculations. This is due to the fact that the load placed on them will be distributed evenly only if the created arc-shaped elements have ideal geometry, that is, the correct shape.

  Let's take a closer look at how to create an arched frame for a canopy with a span of 6 m (L). We will take the distance between the arches to be 1.05 m. With a product height of 1.5 meters, the architectural structure will look aesthetically pleasing and will be able to withstand high loads.

  When calculating the profile length (mн) in the lower belt, use the following formula for the sector length: π R α:180, where the parameter values ​​for this example in accordance with the drawing are equal respectively: R= 410 cm, α÷160°.

  

  After substitution we have:

  3.14 410 160:180 = 758 (cm).

  The structural units should be located on the lower chord at a distance of 0.55 m (rounded) from each other. The position of the extremes is calculated individually.

  In cases where the span length is less than 6 m, welding of complex metal structures is often replaced by a single or double beam, bending the metal profile to a given radius. Although there is no need to calculate the arched frame, however correct selection profiled pipe still remains relevant. After all, the strength of the finished structure depends on its cross-section.

  Calculation of an arched truss from a profile pipe online

  How to calculate the arc length for a polycarbonate canopy

  The arc length of an arch can be determined using Huygens' formula. The middle is marked on the arc, designated by point M, which is located on the perpendicular CM drawn to the chord AB, through its middle C. Then you need to measure the chords AB and AM.

  The arc length is determined by the Huygens formula: p = 2l x 1/3 x (2l – L), where l is the chord AM, L is the chord AB)

  The relative error of the formula is 0.5% if the arc AB contains 60 degrees, and as the angular measure decreases, the error drops significantly. For an arc of 45 degrees. it is only 0.02%.

Today, profile pipe trusses are rightfully considered ideal solution for the construction of garages, residential buildings and outbuildings. Strong and durable, such designs are inexpensive, quick to implement, and anyone with at least a little understanding of mathematics and cutting and welding skills can handle them. And now we will tell you in detail how to choose the right profile, calculate the truss, make jumpers in it and install it. For this we have prepared for you detailed master classes making such farms, video tutorials and valuable advice from our experts!

Stage I. Designing the farm and its elements

So what is a farm? This is a structure that ties the supports together into one cohesive whole. In other words, the truss is a simple architectural structure, among the valuable advantages of which we highlight the following: high strength, excellent performance, low cost and good resistance to deformation and external loads.

Due to the fact that such trusses have a high load-bearing capacity, they are placed under any roofing materials, regardless of their weight.

The use of metal trusses from new or rectangular closed profiles in the construction is considered one of the most rational and constructive solutions. And for good reason:

1. The main secret is savings due to the rational shape of the profile and the connection of all lattice elements.
2. Another valuable advantage of profile pipes for use in truss production is equal stability in two planes, remarkable streamlining and ease of use.
3. Despite their low weight, such trusses can withstand serious loads!

Rafter trusses differ in the outline of the belts, the type of cross-section of the rods and the types of lattice. And with the right approach, you can independently weld and install a truss from a profile pipe of any complexity! Even this one:

Stage II. We purchase a high-quality profile

So, before drawing up a project for future farms, you first need to decide on the following important points:

• contours, size and shape of the future roof;
• material for the manufacture of the upper and lower chords of the truss, as well as its lattice;

Remember one simple thing thing: a frame made of a profile pipe has so-called equilibrium points, which are important to determine for the stability of the entire farm. And it is very important to choose high-quality material for this load:

Trusses are built from profile pipes of the following types of sections: rectangular or square. These are produced different sizes cross-section and diameter, with different wall thicknesses:

• We recommend those that are specially sold for small-sized buildings: these are up to 4.5 meters long and have a cross-section of 40x20x2 mm.
• If you will make trusses longer than 5 meters, then choose a profile with parameters 40x40x2 mm.
• For full-scale construction of the roof of a residential building, you will need profile pipes with the following parameters: 40x60x3 mm.

The stability of the entire structure is directly proportional to the thickness of the profile, so for the manufacture of trusses, do not use pipes that are intended only for welding racks and frames - these have different characteristics. Also pay attention to which method the product was manufactured: electric welded, hot-formed or cold-formed.

If you undertake to make such trusses yourself, then take square-section blanks - they are the easiest to work with. Purchase a square profile 3-5 mm thick, which will be strong enough and its characteristics are close to metal bars. But if you are making a truss just for a visor, then you can give preference to a more budget-friendly option.

Be sure to consider snow and wind loads in your area when designing. After all, the angle of inclination of the trusses is of great importance when choosing a profile (in terms of the load on it):

You can more accurately design a truss from a profile pipe using online calculators.

Let us only note that the simplest structure of a truss made from a profile pipe consists of several vertical posts and horizontal levels onto which rafters for the roof can be attached. You can purchase such a frame ready-made yourself, even to order in any city in Russia.

Stage III. We calculate the internal stress of farms

The most important and responsible task is to correctly calculate the truss from a profile pipe and select the desired format of the internal lattice. For this we need a calculator or something similar. software, as well as some tabular data of SNiPs, which are for this:

• SNiP 2.01.07-85 (impacts, loads).
• SNiP p-23-81 (data on steel structures).

Please review these documents if possible.

Roof shape and angle of inclination

What specific roofing needs a truss? Single-pitch, gable, dome, arched or hipped? The simplest option, of course, is to make a standard lean-to canopy. But you can also calculate and manufacture quite complex trusses yourself:

A standard farm consists of the following important elements, such as the upper and lower chords, racks, braces and auxiliary struts, which are also called trusses. Inside the trusses there is a system of gratings; welds, rivets, special paired materials and gussets are used to connect the pipes.

And, if you are going to make a complex-shaped roof, then such trusses will be an ideal option for it. It is very convenient to make them according to a template directly on the ground, and only then lift them up.

Most often when building a small country house, garage or change house, so-called polonso trusses are used - a special design of triangular trusses connected by ties, and the lower chord here comes out raised.

Essentially, in this case, in order to increase the height of the structure, the lower belt is made broken, and it then amounts to 0.23 of the flight length. For internal space the premises are very comfortable.

So, there are three main options for making a truss, depending on the slope of the roof:

• from 6 to 15°;
• from 15 to 20°;
• from 22 to 35°.

What's the difference you ask? For example, if the angle of the structure is small, up to only 15°, then it is rational to make the trusses trapezoidal in shape. And at the same time, it is quite possible to reduce the weight of the structure itself, taking the height from 1/7 to 1/9 from total length flight.

Those. follow this rule: the less the weight, the greater the height of the truss should be. But if we already have a complex geometric shape, then you need to choose a different type of truss and gratings.

Types of trusses and roof shapes

Here is an example of specific trusses for each type of roof (single, gable, complex):

Let's look at the types of farms:

• Triangular trusses are a classic for making the base for steep roof slopes or sheds. The cross-section of pipes for such trusses must be selected taking into account the weight of the roofing materials, as well as the operation of the building itself. Triangular trusses are good because they have simple shapes and are easy to calculate and implement. They are valued for providing natural light under the roof. But we also note the disadvantages: these are additional profiles and long rods in the central segments of the lattice. And here you will have to face some difficulties when welding sharp support corners.
• Next view - polygonal trusses made of profile pipes. They are indispensable when constructing large areas. Their welding has a more complex shape, and therefore they are not designed for lightweight structures. But such trusses are distinguished by greater metal savings and strength, which is especially good for hangars with large spans.
• Also considered durable parallel belt truss. This truss differs from others in that all its parts are repeating, with the same length of rods, chords and gratings. That is, there are a minimum of joints, and therefore it is easiest to calculate and weld one from a profile pipe.
• A separate type is single slope trapezoidal truss supported by columns. Such a truss is ideal when rigid fixation of the structure is required. It has slopes (braces) on the sides and there are no long rods of the top sheathing. Suitable for roofs where reliability is especially important.

Here is an example of making trusses from a profile pipe as a universal option that is suitable for any garden buildings. It's about about triangular trusses, and you've probably already seen them many times:

A triangular truss with a crossbar is also quite simple, and is quite suitable for building gazebos and cabins:

And here arched farms are already much more complicated to manufacture, although they have a number of valuable advantages:

Your main task is to center the metal truss elements from the center of gravity in all directions, saying in simple language, minimize the load and distribute it wisely.

Therefore, choose the type of farm that is more suitable for this purpose. In addition to those listed above, scissor trusses, asymmetrical, U-shaped, double-hinged, trusses with parallel chords and attic trusses with and without supports are also popular. And also an attic view of the farm:

You will be interested to know that a certain design of internal truss gratings is not selected for aesthetic reasons, but for quite practical ones: to suit the shape of the roof, the geometry of the ceiling and the calculation of loads.

You need to design your farm in such a way that all forces are concentrated specifically at the nodes. Then there will be no bending moments in the belts, braces and trusses - they will work only in compression and tension. And then the cross-section of such elements is reduced to the required minimum, while significantly saving on material. And you can easily make the truss itself hinged.

Otherwise, the force distributed over the rods will constantly act on the truss, and a bending moment will appear, in addition to the total stress. And here it is important to correctly calculate the maximum bending values ​​for each individual rod.

Then the cross-section of such rods should be larger than if the truss itself were loaded with point forces. To summarize: trusses on which the distributed load acts uniformly are made of short elements with hinged joints.

Let's figure out what the advantage of this or that type of grid is in terms of load distribution:

• Triangular The lattice system is always used in parallel chord and trapezoidal trusses. Its main advantage is that it gives the shortest total lattice length.
• Diagonal The system is good for low truss heights. But the material consumption for it is considerable, because here the entire path of effort goes through the nodes and rods of the lattice. Therefore, when designing, it is important to lay a maximum of rods so that the long elements are stretched and the racks are compressed.
• Another type - trussed lattice. It is made in case of loads on the upper belt, as well as when it is necessary to reduce the length of the grating itself. The advantage here is to maintain the optimal distance between the elements of all transverse structures, which, in turn, allows you to maintain the normal distance between the purlins, which will be a practical point for installing roofing elements. But creating such a lattice with your own hands is a rather labor-intensive task with additional metal costs.
• Cruciform the lattice allows you to distribute the load on the truss in both directions at once.
• Another type of lattice - cross, where the braces are attached directly to the wall of the truss.
• And finally semi-diagonal And rhombic gratings, the toughest of those listed. Here two systems of braces interact at once.

We have prepared an illustration for you where we have collected all types of trusses and their gratings together:

Here is an example of how a triangular lattice truss is made:

Making a truss with a diagonal lattice looks like this:

It cannot be said that one type of truss is definitely better or worse than another - each of them is valuable due to its lower consumption of materials, lighter weight, load-bearing capacity and method of fastening. The drawing is responsible for what load pattern will act on it. And the chosen type of lattice will directly determine the weight of the truss, the appearance and labor intensity of its manufacture.

Let us also note this unusual option for making a truss, when it itself becomes a part or support for another, wooden one:

Stage IV. We manufacture and install trusses

We will give you some valuable tips on how to independently weld such trusses right on your own site without much difficulty:

• Option one: you can contact the factory, and they will custom-make all the necessary individual elements according to your drawing, which you just have to weld on site.
• Second option: purchase a ready-made profile. Then all you have to do is cover the inside of the trusses with boards or plywood, and lay insulation in between, if necessary. But this method will, of course, cost more.

Here, for example, is a good video tutorial on how to lengthen a pipe by welding and achieve ideal geometry:

Here is also a very useful video on how to cut a pipe at a 45° angle:

So, now we come directly to the assembly of the trusses themselves. The following step-by-step instructions will help you cope with this:

• Step 1: First prepare the trusses. It is better to weld them directly on the ground in advance.
• Step 2. Install vertical supports for future trusses. It is vital that they are truly vertical, so test them with a plumb line.
• Step 3. Now take the longitudinal pipes and weld them to the support posts.
• Step 4. Raise the trusses and weld them to the longitudinal pipes. After this, it is important to clean all connection points.
• Step 5. Paint the finished frame with special paint, having previously cleaned and degreased it. Pay special attention to the joints of the profile pipes.

What else do those who make such farms at home face? First, think in advance about the support tables on which you will place the truss. Throwing it on the ground is far from the best option - it will be very inconvenient to work with.

Therefore, it is better to install small bridge supports that will be slightly wider than the lower and upper chords of the truss. After all, you will manually measure and place jumpers between the belts, and it is important that they do not fall to the ground.

The next important point: trusses made from profile pipes are heavy in weight, and therefore you will need the help of at least one more person. In addition, it wouldn’t hurt to have help with such tedious and painstaking work as sanding metal before cooking.

Also in some designs it is necessary to combine different types trusses to attach the roof to the wall of the building:

Also keep in mind that you will need to cut a lot of trusses for all the elements, and therefore we advise you to either purchase or build homemade machine similar to the one in our master class. Here's how it works:

So, step by step, you will draw up a drawing, calculate the truss lattice, make blanks and weld the structure on site. Moreover, you will also be using up the remains of the profile pipes, therefore, you will not need to throw anything away - all this will be needed for minor parts of the canopy or hangar!

Stage V. Clean and paint the finished trusses

After you install the farms on their permanent place, be sure to treat them with anti-corrosion compounds and paint them with polymer paints. Paint that is durable and UV resistant is ideal for this purpose:

That's all, the profile pipe farm is ready! All that remains is the finishing work of covering the trusses from the inside with finishing and on the outside with roofing material:

Believe me, making a metal truss from a profile pipe will actually not be difficult for you. A huge role is played by a well-drawn drawing, high-quality welding of a truss from a profile pipe and the desire to do everything correctly and accurately.

• Truss structures made from profile pipes
• Calculation for canopy
• Recommendations for the right choice and production of tubular metal structures

When the area of ​​the structure is large enough, the issue of ensuring the reliability and strength of the structure becomes particularly important. There is a need to strengthen the rafter system, the rafters of which could cover fairly long spans.
Trusses made from profile pipes are metal structures assembled using lattice rods. Manufacturing metal trusses is a more labor-intensive process than in the case of solid beams, but more economical. In production, paired material is used, and scarves are used as connecting parts. The entire structure is assembled using welding or riveting.

With their help, you can cover spans of any length, however, it is worth noting that proper installation requires competent calculations. Then, provided that the welding work is carried out with high quality, all that remains is to move the pipe assemblies upstairs and install them according to top harness, according to the markup.

Load-bearing trusses made from profile pipes have many undeniable advantages:

• minimum weight;
• they are durable;
• hardy;
• the nodes are very strong and therefore can withstand high loads;
• with their help you can build structures with complex geometries;
• allow you to save money financial resources, since prices for the manufacture of metal structures from profile pipes are quite acceptable for solving a wide range of problems.

The division of these structures into specific types is based on different parameters. Let's start with the main thing -

• Number of belts.

There are:

• supports, the components of which are located in a single plane;
• hanging, they consist of two belts, according to their location they are called lower and upper, respectively.

According to the first parameter, they distinguish:

• arched trusses made of profile pipes,
• there are also straight ones ;
• single or double slope.

According to the contour, there are:

• having a parallel belt. This is the best option for arranging a soft roof. Such a support is assembled very simply, since its components are identical parts and, importantly, the dimensions of the lattice coincide with the dimensions of the rods for the belt;

• single-pitched. They are distinguished by rigid nodes that allow them to absorb significant external loads. Their construction requires a small amount of material, so these structures are quite economical;
• polygonal. Although they are able to withstand a lot of weight, however, their installation is labor-intensive and quite complicated;
• triangular. They are practically indispensable when constructing roofs with a large angle of inclination. Their only drawback is the large amount of waste during construction.

• Tilt angle. Typical profile pipe trusses are divided into three groups:

• 22°- 30°. The height and length of the metal structure in this case are related as one to five. This is the best option for covering small spans in domestic construction. Their main advantage is their low weight. Triangular ones are most suitable for such an analogue.

For spans longer than 14 m, braces are used, which are installed from top to bottom. A panel (about 150 – 250 cm in length) is placed along the upper belt. Thus, with these initial data we have a design that includes two belts. The number of panels is even.

If the span exceeds 20 m, then there is a need for a sub-rafter metal structure connected by supporting columns.

The so-called Polonso farm deserves special mention. It consists of two triangular systems connected to one another through a tie. This design solution avoids the installation of long braces in the middle panels, which leads to a significant reduction in overall weight.

• 15°-22°. The ratio of height and length in this case is one to seven. The maximum permissible length for such a frame is 20 m. If, according to operating conditions, it is necessary to increase its height, then the lower belt is made broken.
• less than 15°. In such projects it is recommended to use trapezoidal metal rafters. The presence of short struts in them helps to increase resistance to longitudinal bending.

Attention!

Trusses made of profile pipes for a pitched roof with a slope angle of 6–10° should have an asymmetrical shape.

Heights are determined by dividing the span length into seven, eight or nine parts, taking as a basis the features of a given structure.

Calculation for canopy

The calculations are based on the requirements of SNiP:

A mandatory component of any calculation and subsequent installation of a structure is a drawing.

A diagram is prepared indicating the relationship between the length of the metal structure and the roof slope.

• It also takes into account the outlines of the support belts. The contour of the belt is determined by the purpose of the structure, the type of roof covering and the angle of inclination.
• When choosing sizes, as a rule, the principle of economy is followed, unless, of course, TTs require otherwise. The height of the structure is determined by the type of overlap, the minimum total weight, the ability to move, the length is the established slope.

For truss lengths exceeding 36 m, the construction lift is additionally calculated.

• The dimensions of the panels are calculated taking into account the loads absorbed by the structure. It should be remembered that the angles of the braces differ for different metal rafters, but the panel must correspond to them. For a triangular lattice, the required angle is 45°, for a slanted lattice – 35°.
• The calculation is completed by determining the gap between the nodes. Usually it corresponds to the width of the panel.

Calculations are carried out taking into account the fact that an increase in height leads to an increase in load-bearing capacity. Snow cover will not linger on such a canopy. One way to strengthen trusses from a profile pipe is to install several strong stiffeners.

To determine the dimensions of metal structures for canopies, follow the following data:

• for structures with a width of no more than 4.5 m, products measuring 40 by 20 by 2 mm are used;
• less than 5.5 m – 40 by 40 by 2 mm;
• over 5.5 m, products measuring 40 by 40 by 3 mm or 60 by 30 by 2 mm will be optimal.

When calculating the pitch, it is necessary to take into account that the greatest possible distance from one canopy support to another is 1.7 m. If this limitation is violated, the strength and reliability of the structure will be in question.

When the necessary parameters are completely obtained, the corresponding design diagram is obtained using formulas and special programs. Now all that remains is to think about how to weld the truss correctly.

On a note

The calculations should take into account:

• purchase cost of one ton of metal;
• prices for the manufacture of metal structures from profile pipes (or you can sum up the individual costs of welding, anti-corrosion treatment, installation).

Recommendations for the correct selection and production of tubular metal structures

• When choosing a standard size, it is advisable to opt for rectangular or square products, since the existing two stiffeners will provide the finished metal structure with the greatest stability.
• Use only high-quality products made from high-carbon alloy steel, which does not corrode and is resistant to aggressive influences external environment. The wall thickness and diameter are selected in accordance with those laid down in the project. This will ensure the required load-bearing capacity of the metal rafters.
• To connect the main components of the truss to each other, tacks and paired angles are used.
• In the upper belt, to close the frame, versatile I-angles are needed, and the joining is performed on the smaller side.
• To pair the parts of the lower belt, equilateral corners are used.
• The main parts of long structures are connected using overhead plates.

• The braces are installed at 45 degrees, and the racks are installed at right angles. Having completed the assembly of the main structure, they proceed to welding the truss from the profile pipe. Each of the welding seams must be checked for quality, since they determine the reliability of the future structure. After welding is completed, metal rafters are treated with special anti-corrosion compounds and coated with paint.

Making metal trusses for a canopy on video.

© 2018 stylekrov.ru

Pipe and polycarbonate canopies are becoming increasingly popular architectural form on a personal plot. No wonder, because this building can perform many functions, ranging from an open garage for a car, a wood warehouse, an indoor playground and ending with a recreation area with a barbecue and soft chairs.

The key advantage is the ability to make such a design with your own hands. This article will provide recommendations on the choice of material, examples of calculations of supports and trusses, and how to weld a canopy from a profile pipe.

Calculation of the optimal canopy shape

The length of the rafter depends on the angle of inclination of the truss. For different angles, it is optimal to use different roofing materials:

• 22-30 is the optimal angle of inclination for buildings in areas with significant snow loads. The design of a canopy made from a profile pipe with such an angle provides a predominantly triangular shape. It is optimal for straight and corrugated asbestos sheets, various types of metal profiles and ethernite roofing.
• 15-22 – are also gable with metal types roofing coverings. This angle of inclination is typical for regions with increased wind loads. The maximum span of a triangular truss with this angle is 20 m.
• 6-15 – predominantly single-pitched trapezoidal trusses covered with polycarbonate and corrugated sheets.

Single-pitch canopy made of profile pipe, photo of a structure with a roof made of corrugated sheets

Calculation of a canopy made of polycarbonate from a profile pipe is carried out in accordance with SNiP P-23-81 “Steel Structures” and SNiP 2.01.07-85 “Loads and Impacts”.

The technological requirements for the farm and the calculation sequence are as follows. In accordance with the technical specifications, the required span is determined. Using the presented diagram, we substitute the dimensions of the span and determine the height of the structure. The angle of inclination of the truss and the optimal shape of the canopy roof are set. Accordingly, the contours of the upper and lower chords of the truss, the general outlines and type of roofing are determined.

Important! The maximum distance at which trusses are placed when making a canopy from a profile pipe is 1.75 m.

Diagram of the dependence of the length of the rafters on the angle of the roof when calculating a truss from a profile pipe for a canopy

Profile selection

As a material for assembling a truss, you can use channels, tees, angles and other profiled products made from steel grade St3SP or 09G2S (in accordance with GOST). However, all these materials have a significant drawback compared to profiled pipes - they are much heavier and thicker with comparable strength characteristics.

The dimensions of the frame elements for a canopy made from a profile pipe depend on the dimensions of the building. In accordance with GOST 23119-78 and GOST 23118-99 to create a canopy from square pipe with their own hands they use the following materials:

• For compact buildings with a span of up to 4.5 m – 40x20x2 mm;
• Medium-sized structures with a span of up to 5.5 m are made of corrugated pipe 40x40x2mm;
• Structures of significant size with spans of more than 5.5 m are assembled from profile pipes of various sections 40x40x3 mm or 60x30x2mm.
• The size of the canopy stand made from corrugated pipe is 80 80 by 3 mm.

Drawings, dimensions and main connections

Before you start assembling a canopy from a profile pipe with your own hands, you need to draw detailed plan the entire structure indicating the exact dimensions of all elements. This will help calculate the exact amount of materials of each type and calculate the cost of construction.

Drawing of a canopy made from a profile pipe indicating the main overall dimensions

In addition, it is advisable to make an additional drawing of the most complex structures. In this case, it is a single-pitched truss and the fastening points of its main elements.

Scheme for making a truss from a profile pipe for a canopy with the main fastening units

One of the main advantages of a profile pipe is the possibility of a faceless connection. This is manifested in the simplicity of the design and low cost of the truss with a length of rafter spans of up to 30 m. In this case, the roofing material can rest directly on the upper chord of the truss, provided it is sufficiently rigid.

Fastening points for assembling a canopy from a profile pipe with your own hands, in the photo a - a triangular lattice, b - a support lattice, c - a diagonal lattice

The advantages of a bevelless welded joint are:

• Significant reduction in truss weight, compared to riveted or bolted structures, up to 20% and 25%, respectively.
• Reducing labor costs and manufacturing costs, both for single products and for small-scale production.
• Low cost of welding and the ability to automate the process by using devices with a device for continuous feeding of welded wire.
• Equal strength of the weld and the products being connected.

Disadvantages include:

• The need to have quite expensive equipment;
• Welding experience required.

Bolted connections in the production of products from profile pipes are quite common. They are usually used in collapsible awnings made of profile pipes or in products produced for mass consumption.

Bolted connections are the simplest for installing a canopy from a profile pipe with your own hands, photo of the attached frame element

The main advantages of such connections are:

• Easy to assemble;
• No additional equipment required;
• Opportunity complete dismantling structures.

Flaws:

• The weight of the structure increases;
• Additional fasteners required;
• The strength and reliability of bolted connections is somewhat lower than welded ones.

Summing up

The article examined the design and methods of making the simplest single-pitch canopy from a profile pipe with your own hands, however, profiled pipe is a rather “flexible” material from which complex and aesthetically attractive structures can be made.

A complex design for creating a canopy from a corrugated pipe with your own hands, photo of a lean-to, dome structure

Canopies on a metal frame make life easier. They will protect the car from bad weather, cover the summer veranda and gazebo. They will replace the roof of the workshop or the canopy over the entrance. By turning to professionals, you will get any canopy you want. But many can handle the installation work themselves. True, you will need an accurate calculation of the truss made from a profile pipe. You cannot do without the appropriate equipment and materials. Of course, welding and cutting skills are also required.

Frame material

The basis of canopies is steel, polymers, wood, aluminum, reinforced concrete. But, more often the frame is made up of metal trusses from a profile pipe. This material is hollow, relatively light, but durable. In cross-section it looks like:

• rectangle;
• square;
• oval (as well as semi- and flat-oval figures);
• polyhedron.

When welding trusses from a profile pipe, they often choose a square or rectangular section. These profiles are easier to process.

Variety of pipe profiles

Permissible loads depend on the wall thickness, metal grade, and manufacturing method. The material is often high-quality structural steel (1-3ps/sp, 1-2ps(sp)). For special needs, low-alloy alloys and galvanization are used.

The length of profile pipes usually ranges from 6 m for small sections to 12 m for large sections. The minimum parameters are from 10×10×1 mm and 15×15×1.5 mm. With increasing wall thickness, the strength of the profiles increases. For example, on sections 50×50×1.5 mm, 100×100×3 mm and above. Products maximum dimensions(300×300×12 mm and more) are more suitable for industrial buildings.

Regarding the parameters of frame elements, there are the following recommendations:

• for small-sized canopies (up to 4.5 m wide), pipe material with a cross-section of 40×20×2 mm is used;
• if the width is up to 5.5 m, the recommended parameters are 40x40x2 mm;
• for sheds of larger sizes, it is recommended to take pipes of 40×40×3 mm, 60×30×2 mm.

What is a farm

A truss is a rod system, a base building structure. It consists of straight elements connected at nodes. For example, we consider the design of a truss made of a profile pipe, in which there is no misalignment of the rods and no extra-nodal loads. Then in her components only tensile and compressive forces will arise. The mechanics of this system allows it to maintain geometric invariance when replacing rigidly mounted units with hinged ones.

Example of a welded rod system

The farm consists of the following elements:

• top belt;
• lower belt;
• stand perpendicular to the axis;
• strut (or brace) inclined to the axis;
• auxiliary support brace (sprengel).

The lattice system can be triangular, diagonal, semi-diagonal, cross. For connections, scarves, paired materials, rivets, and welds are used.

Mounting options in nodes

Making trusses from a profile pipe involves assembling a belt with a certain outline. By type they are:

• segmental;
• polygonal;
• gable (or trapezoidal);
• with parallel belts;
• triangular (d-i);
• with a raised broken lower belt;
• single-pitched;
• console.

Types according to the outlines of the belts

Some systems are easier to install, others are more economical in terms of material consumption, and others are easier to construct support units.

Truss Calculation Basics

Influence of inclination angle

The choice of design for canopy trusses made from profile pipes is related to the slope of the structure being designed. There are three possible options:

• from 6° to 15°;
• from 15° to 22°;
• from 22° to 35°.

At a minimum angle (6°-15°), trapezoidal contours of the belts are recommended. To reduce weight, a height of 1/7 or 1/9 of the total span length is allowed. When designing a flat canopy of a complex geometric shape, it is necessary to raise it in the middle part above the supports. Take advantage of Polonso farms, recommended by many experts. They are a system of two triangles connected by tightening. If you need a tall structure, it is better to choose a polygonal structure with a raised lower chord.

When the slope angle exceeds 20°, the height should be 1/7 of the total span length. The latter reaches 20 m. To increase the structure, the lower belt is made broken. Then the increase will be up to 0.23 span lengths. To calculate the required parameters, use tabular data.

Table for determining the slope of the rafter system

For slopes greater than 22°, calculations are carried out using special programs. Awnings of this kind are more often used for roofing made of slate, metal and similar materials. Here, triangular trusses from a profile pipe are used with a height of 1/5 of the entire span length.

The greater the angle of inclination, the less precipitation and heavy snow will accumulate on the canopy. The load-bearing capacity of the system increases with increasing its height. For additional strength, additional stiffening ribs are provided.

Base Angle Options

To understand how to calculate a truss from a profile pipe, it is necessary to find out the parameters of the basic units. For example, span dimensions should usually be specified in the technical specifications. The number of panels and their dimensions are pre-assigned. Let's calculate the optimal height (H) in the middle of the span.

• If the chords are parallel, polygonal, trapezoidal, Н=1/8×L, where L is the length of the truss. The top chord should have a slope of about 1/8×L or 1/12×L.
• For triangular type, on average, H=1/4×L or H=1/5×L.

The grille braces should have an inclination of approximately 45° (within 35°-50°).

Use a ready-made standard project, then you won’t have to make calculations

In order for the canopy to be reliable and last a long time, its design requires precise calculations. After the calculation, materials are purchased, and then the frame is installed. There is a more expensive way - to purchase ready-made modules and assemble the structure on site. Another more difficult option is to do the calculations yourself. Then you will need data from special reference books on SNiP 2.01.07-85 (impacts, loads), as well as SNiP P-23-81 (data on steel structures). You need to do the following.

1. Decide on the block diagram in accordance with the functions of the canopy, the angle of inclination, and the material of the rods.
2. Select options. Take into account the relationship between the height and minimum weight of the roof, its material and type, slope.
3. Calculate the panel dimensions of the structure according to the distance individual parts, responsible for transferring loads. The distance between adjacent nodes is determined, usually equal to the width of the panel. If the span is over 36 m, the construction lift is calculated - the reverse damped bending that acts due to the loads on the structure.

Among the methods for calculating statically determinate trusses, one of the simplest is considered to be cutting out nodes (areas where the rods are hingedly connected). Other options are the Ritter method, the Henneberg rod replacement method. As well as a graphical solution by drawing up a Maxwell-Cremona diagram. In modern computer programs, the method of cutting nodes is more often used.

For a person who has knowledge of mechanics and strength of materials, calculating all this is not so difficult. The rest should take into account that the service life and safety of the canopy depend on the accuracy of the calculations and the magnitude of errors. It may be better to turn to specialists. Or choose an option from ready-made design solutions, where you can simply substitute your values. When it is clear what type is needed roof truss from a profile pipe, a drawing for it will probably be found on the Internet.

Significant factors for site selection

If the canopy belongs to a house or other building, it will require official permission, which will also have to be taken care of.

First, the site where the structure will be located is selected. What does this take into account?

1. Constant loads (fixed weight of sheathing, roofing and other materials).
2. Variable loads (impacts of climatic factors: wind, precipitation, including snow).
3. A special type of load (is there seismic activity in the region, storms, hurricanes, etc.).

Also important are the characteristics of the soil, the influence standing nearby buildings. The designer must take into account all significant factors and clarifying coefficients that are included in the calculation algorithm. If you plan to carry out calculations on your own, use 3D Max, Arkon, AutoCAD or similar programs. There is a calculation option in online versions of construction calculators. Be sure to find out for the intended project the recommended spacing between load-bearing supports and sheathing. As well as parameters of materials and their quantity.

An example of a software calculation for a canopy covered with polycarbonate

Sequence of work

The assembly of a frame from metal profiles should only be carried out by a welding specialist. This important task requires knowledge and skillful handling of the tool. You not only need to understand how to weld a truss from a profile pipe. It is important which units are best assembled on the ground, and only then lifted onto supports. If the structure is heavy, equipment will be required for installation.

Typically the installation process takes place in the following sequence:

1. The site is being marked. Embedded parts and vertical supports are installed. Often, metal pipes are immediately placed in the pits and then concreted. The verticality of the installation is checked with a plumb line. To control parallelism, a cord or thread is pulled between the outer posts, the rest are aligned along the resulting line.
2. The longitudinal pipes are fixed to the supports by welding.
3. The components and elements of the trusses are welded on the ground. Using braces and jumpers, the belts of the structure are connected. Then the blocks should be raised to the desired height. They are welded to longitudinal pipes along the areas where vertical supports are located. Longitudinal jumpers are welded between the trusses along the slope for further fastening of the roofing material. Holes are made in them for fasteners.
4. All connecting areas are thoroughly cleaned. Especially the upper edges of the frame, where the roof will later lie. The surface of the profiles is cleaned, degreased, primed and painted.

Taking advantage finished project, you will quickly start assembling the canopy

Experts advise performing such responsible work only if you have the appropriate experience. It is not enough to know in theory how to properly weld a truss from a profile pipe. Having done something wrong, ignoring the nuances, House master takes risks. The canopy will fold and collapse. Everything underneath it will suffer - cars or people. So take this knowledge to heart!

Video: how to weld a truss from a profile pipe

Determination of internal truss forces

Often we do not have the opportunity to use a conventional beam for a particular structure, and we are forced to use a more complex structure called a truss.
although it differs from the calculation of a beam, it will not be difficult for us to calculate it. All you will need is attention, basic knowledge of algebra and geometry, and an hour or two of free time.
So, let's begin. Before calculating the farm, let's consider some real situation that you might encounter. For example, you need to cover a garage that is 6 meters wide and 9 meters long, but you have neither floor slabs nor beams. Only metal corners of various profiles. These are the ones we will use to assemble our farm!
Subsequently, purlins and corrugated sheeting will rest on the truss. The support of the truss on the walls of the garage is hinged.

First, you will need to know all the geometric dimensions and angles of your truss. This is where we need our mathematics, namely geometry. We find angles using the cosine theorem.

Then you need to collect all the loads on your farm (you can see it in the article). Suppose you have the following loading option:

Next, we need to number all the elements and nodes of the truss and set the support reactions (the elements are labeled in green, and the nodes in blue).

To find our reactions, we write the equilibrium equations for forces on the y-axis and the equilibrium equation for moments about node 2.

Ra+Rb-100-200-200-200-100=0;
200*1.5 +200*3+200*4.5+100*6-Rb*6=0;

From the second equation we find the support reaction Rb:

Rb=(200*1.5 +200*3+200*4.5+100*6) / 6;
Rb=400 kg

Knowing that Rb=400 kg, from the 1st equation we find Ra:

Ra=100+200+200+200+100-Rb;
Ra=800-400=400 kg;

Once the support reactions are known, we must find the node where there are the fewest unknown quantities (each numbered element is an unknown quantity). From this point on, we begin to divide the truss into separate nodes and find the internal forces of the truss rods at each of these nodes. It is based on these internal efforts that we will select the sections of our rods.

If it turns out that the forces in the rod are directed from the center, then our rod tends to stretch (return to its original position), which means it itself is compressed. And if the forces of the rod are directed towards the center, then the rod tends to compress, that is, it is stretched.

So, let's move on to the calculation. In node 1 there are only 2 unknown quantities, so let’s consider this node (we set the directions of efforts S1 and S2 for our own reasons, in any case, we will get it right in the end).

Consider the equilibrium equations on the x and y axes.

S2 * sin82.41 = 0; - on the x axis
-100 + S1 = 0; - on the y axis

From the 1st equation it is clear that S2=0, that is, the 2nd rod is not loaded!
From the 2nd equation it is clear that S1=100 kg.

Since the value of S1 turned out to be positive, it means that we chose the direction of effort correctly! If it turned out to be negative, then the direction should be changed and the sign changed to “+”.

Knowing the direction of force S1, we can imagine what the 1st rod is like.

Since one force was directed to the node (node ​​1), the second force will be directed to the node (node ​​2). This means our rod is trying to stretch, which means it is compressed.
Next, consider node 2. There were 3 unknown quantities in it, but since we have already found the value and direction of S1, only 2 unknown quantities remain.

Yet again

100 + 400 – sin33.69 * S3 = 0 - on the y axis
- S3 * cos33.69 + S4 = 0 - on the x axis

From the 1st equation S3 = 540.83 kg (rod No. 3 is compressed).
From the 2nd equation S4 = 450 kg (rod #4 is stretched).
Consider the 8th node:

Let's create equations on the x and y axes:

100 + S13 = 0 - on the y axis
-S11 * cos7.59 = 0 - on the x axis

From here:

S13 = 100 kg (rod #13 compressed)
S11 = 0 (zero rod, no force in it)

Consider the 7th node:

Let's create equations on the x and y axes:

100 + 400 – S12 * sin21.8 = 0 - on the y axis
S12 * cos21.8 - S10 = 0 - on the x axis

FROM the 1st equation we find S12:

S12 = 807.82 kg (rod #12 compressed)

From the 2nd equation we find S10:

S10 = 750.05 kg (rod #10 stretched)

Next, let's look at node No. 3. As far as we remember, the 2nd rod is zero, which means we won’t draw it.

Equations on the x and y axis:

200 + 540.83 * sin33.69 – S5 * cos56.31 + S6 * sin7.59 = 0 - on the y axis
540.83 * cos33.69 – S6 * cos7.59 + S5 * sin56.31 = 0 - on the x axis

And here we will need algebra. I will not describe in detail the method for finding unknown quantities, but the gist is this: we express S5 from the 1st equation and substitute it into the 2nd equation.
As a result we get:

S5 = 360.56 kg (rod #5 stretched)
S6 = 756.64 kg (rod #6 compressed)

Let's consider node No. 6:

Let's create equations on the x and y axes:

200 – S8 * sin7.59 + S9 * sin21.8 + 807.82 * sin21.8 = 0 - on the y axis
S8 * cos7.59 + S9 * cos21.8 – 807.82 * cos21.8 = 0 - on the x axis

Just like in the 3rd node, we will find our unknowns.

S8 = 756.64 kg (rod #8 compressed)
S9 = 0 kg (rod No. 9 zero)

Let's consider node No. 5:

Let's make up the equations:

200 + S7 – 756.64 * sin7.59 + 756.64 * sin7.59 = 0 - per y axis
756.64 * cos7.59 – 756.64 * cos7.59 = 0 - on the x axis

From the 1st equation we find S7:

S7 = 200 kg (rod #7 compressed)

To check our calculations, let’s consider the 4th node (there are no forces in rod No. 9):

Let's create equations on the x and y axes:

200 + 360.56 * sin33.69 = 0 - on the y axis
-360.56 * cos33.69 – 450 + 750.05 = 0 - on the x axis

In the 1st equation it turns out:

In the 2nd equation:

This error is acceptable and is most likely related to the angles (2 decimal places instead of 3).
As a result, we get the following values:

I decided to double-check all our calculations in the program and got exactly the same values:

Selection of cross-section of truss elements

At calculation of a metal truss after all the internal forces in the rods have been found, we can begin to select the cross-section of our rods.
For convenience, we summarize all values ​​in a table.

It has the simplest design, since there are no additional elements - transitions, skates, etc. It is an inclined plane (slope) covering a building (or part of it) to protect it from precipitation and compensate for wind loads.

Improper roof arrangement results in unnecessary loads on the walls and foundation, the formation of leaks, failure of the rafter system and damage to the entire building.

Therefore, all its elements must be carefully calculated taking into account all existing factors.

Such as:

• Climatic conditions.
• The size of the building, the number of floors.
• Roofing material.
• The insulation used.
• roofs.

Such parameters have great influence on the load experienced by the rafter system and walls, so all calculations are based on them.

In this article we will tell you what a calculator for calculating a pitched roof is, which will help you in calculating the structure of a truss.

The calculator produces calculation of the roof of a pitched roof.
Before starting the calculations, In the upper right corner of the calculator you need to select a roofing covering.

Designation of fields in the calculator

Specify roofing material:

Select a material from the list -- Slate (corrugated asbestos cement sheets): Medium profile (11 kg/m2) Slate (corrugated asbestos cement sheets): Reinforced profile (13 kg/m2) Corrugated cellulose-bitumen sheets (6 kg/m2) Bitumen (soft , flexible) tiles (15 kg/m2) Galvanized sheet (6.5 kg/m2) Sheet steel (8 kg/m2) Ceramic tiles(50 kg/m2) Cement-sand tiles (70 kg/m2) Metal tiles, corrugated sheets (5 kg/m2) Keramoplast (5.5 kg/m2) Seam roofing (6 kg/m2) Polymer-sand tiles (25 kg/m2) m2) Ondulin (Euro slate) (4 kg/m2) Composite tiles (7 kg/m2) Natural slate (40 kg/m2) Specify the weight of 1 square meter of coating (? kg/m2)

kg/m2

Enter roof parameters:

Base width A (cm)

Base length D (cm)

Lifting height B (cm)

Length of side overhangs E (cm)

Front and rear overhang length C (cm)

Rafters:

Rafter pitch (cm)

Type of wood for rafters (cm)

Working area of ​​the side rafter (optional) (cm)

Lathing calculation:

Sheathing board width (cm)

Sheathing board thickness (cm)

Distance between sheathing boards
(cm)

Snow load calculation:

Select your region using the map below

1 (80/56 kg/m2) 2 (120/84 kg/m2) 3 (180/126 kg/m2) 4 (240/168 kg/m2) 5 (320/224 kg/m2) 6 ​​(400/280 kg/m2) 7 (480/336 kg/m2) 8 (560/392 kg/m2)

Wind load calculation:

Ia I II III IV V VI VII

Height to the ridge of the building

5 m from 5 m to 10 m from 10 m

Terrain type

Open area Closed area Urban areas

Calculation results

Roof angle: 0 degrees.

The angle of inclination is suitable for this material.

It is advisable to increase the angle of inclination for this material!

It is advisable to reduce the angle of inclination for this material!

Roof surface area: 0 m2.

Approximate weight of roofing material: 0 kg.

Number of rolls of insulating material with 10% overlap (1x15 m): 0 rolls.

Rafters:

Load on the rafter system: 0 kg/m2.

Rafter length: 0 cm

Number of rafters: 0 pcs.

Lathing:

Number of rows of sheathing: 0 rows.

Uniform distance between sheathing boards: 0 cm

Number of sheathing boards with a standard length of 6 meters: 0 pcs.

Volume of sheathing boards: 0 m3.

Approximate weight of sheathing boards: 0 kg.

Description of calculator fields

Snow load region

Impact on rafters and roofing

Calculation of loads on rafters and roofing consists of two terms:

. This is the own weight of the rafters and roofing, and all roof elements.. Long-term or short-term forces of different directions caused by the weight of snow in winter, the influence of wind, etc. are taken into account.

The constant load is determined by summing the weight of all elements present on the roof, and the payload is also taken into account - the weight of expansion tanks, attic cladding, windows or other objects that load the roof and under-roof space.

If for constant loads the calculation does not look complicated, then take account natural factors it will be more difficult. Data will be required on the prevailing wind directions and strength, cases of hurricane squalls, the amount of snow in winter time, its quality indicators are that dry snow is much lighter than wet snow.

CAREFULLY!

In order for the calculation to be correct, it is necessary to take into account limit states, since they are the most dangerous and destructive.

Snow load calculation produced according to the formula:

S = Sg * µ

Where Sg- the weight of snow per 1 square meter of plane that falls in a given area.

µ — a correction factor that takes into account the angle of inclination of the roof (for flat roofs up to 25° it is equal to 1, for steeper ones - 0.7).

When the roof slope is 60° or higher, the weight of the snow is not taken into account.

is calculated like this:

W = Wo * k

Wo- a standard indicator of wind strength for a given area.

k— correction factor taking into account the type of terrain and height above the ground.

Both formulas show the load per 1 sq.m., to obtain full meaning You need to multiply the result by the roof area.

It should also be understood that these calculations do not always take into account maximum loads or special cases - for example, snow accumulations or isolated strong gusts of wind that are not typical for a given area, but sometimes occur. For that, to have a guarantee of strength, it is necessary to accept the load with a margin of 15% - 20% of the calculated one.

Rafter system

Quantity of roof covering for a pitched roof

The roofing calculation is based on individual characteristics of the material. A simple calculation of the roof area in this case will be very approximate, since the size of the longitudinal and transverse overlap and the size of the sheet will not be taken into account.

That is, the area of ​​the sheet of roofing material is not fully used, Only the useful part is taken into account in the calculation. Each type of material has its own, determined by the size of the wave or the pitch of the ribs.

In addition, it is necessary to take into account the size of the canopies or overhangs, which also consume roofing material. If you are not completely confident in the quality of your own calculation, it is recommended to use our pitched roof calculator.

Roofing kit for metal tiles

Quantity of sheathing for a pitched roof

The amount of sheathing directly depends on what roofing coating will be used in this case. The sheathing strips should be spaced in increments corresponding to the dimensions of the sheet of material.

This consistency is very important without him correct installation roofing material will be complicated or completely impossible. Therefore, to calculate the amount of sheathing, you first need to determine its pitch. You can refer to SNiP, which contains detailed and accurate information about the rules for installing all roofing elements.

For continuous lathing is often used, when the distance between the slats is 2-2.5 cm. In this case, the calculation of the sheathing comes down to dividing the length of the roof by the width of the slats plus 2 cm for the gap.

More rigid types of material do not require continuous sheathing and the calculation is made based on the distance between the slats used for this type of roof.

A simpler solution would be to use online calculators that perform specialized calculations according to the specified. The obtained data should be clarified by recalculation using another online calculator.

Number of sheathing

Calculation of material for rafters of a pitched roof

- basic load-bearing element for roofing and under-roofing elements. Insufficiently careful calculations or incompletely taken into account loads can cause sagging or deflection of the rafters, which will lead to leaks and damage to the entire building.

To make the calculation, you must first decide on the choice of material. In this case should follow the traditional approach and use edged pine board 50 by 150 mm. This choice is time-tested; pine absorbs little atmospheric moisture, it is light and quite durable.

ATTENTION!

At the same time, it is important to dry the boards before installation work so that when they dry out, they do not become deformed and do not violate the geometry of the system.

In addition, you need to take into account:

• The purpose of the building, in particular the attic space.
• Roof dimensions, length and slope angle.
• Roofing material.
• Amount of snow and wind strength.

Taking these factors into account will help determine the optimal distance between the rafters, and also calculate the amount of lumber. If the length of the slope is more than 6.5 m, then the installation of additional racks will be required.

The standard rafter pitch usually ranges from 60-70 cm, which allows for a simplified calculation of the system. That being said, it is recommended that you turn to online calculators to check your results.

A pitched roof has the simplest structure, but the space underneath is more difficult to use for residential purposes. Most often, this option is used for outbuildings or auxiliary buildings, when the attic is not considered as a living space.

In such cases, the weight and load from the roof on the walls is reduced due to the absence of an insulating layer, which simplifies construction and reduces the cost of materials.

Material calculation

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