Types and installation of drainage funnels for flat roofs. Installation of funnels on soft roofs Storm funnels for roofing
In addition to the fact that rain and melt water enters storm drainage from the surface of the earth, they are also discharged from the roof of the house. These drains are called internal.
In a house, an internal drain drains rain or melt water from the roof through pipelines located inside the building. From these same pipes water flows into external network rainwater drainage (closed outlet) or onto the sidewalk (open outlet).
Installation of drainage funnels
The drain is usually made of pressure asbestos-cement, steel or plastic pipes. In the presence of vibration loads, steel pipes must be used.
Drain funnels can be of several types (example in Fig. 117). The drainage funnel consists of a body installed in the ceiling, a frame, and a grate (cap) for retaining large debris. The funnel is hermetically connected to the roof so that moisture cannot seep in and damage the ceiling. A layer of waterproofing material is fixed between the body and frame using bolts and sealed with mastic. Today you can find drainage funnels following diameters: 80, 100, 150 and 200 mm.
Rice. 117. Drain funnels:
A - flat funnels with gratings; b, c – bell funnels; 1 – grid; 2 – frame; 3 – body; 4 – jet straightener; 5 – cap
Drainage funnels with gratings are usually installed on flat roofs, funnels with caps are usually installed on pitched and flat roofs. Since the funnels are cylindrical in shape, with a strong flow of water, turbulence is formed, thereby reducing their throughput. Therefore, in order to increase their throughput capacity, special stream straighteners are used, which prevent the formation of turbulence at the edge of the drainage funnel and prevent the narrowing of the flow area.
Atmospheric and melt moisture enters the closed drainage network through a storm inlet (example in Fig. 118), which is a well covered with a grate. Storm water inlets can be round or rectangular. The bottom of such a well should have a smooth outline, without a pit for sediment.
The drainage ditch must be connected to a closed network through a well with a settling part.
As a rule, storm water inlets are installed at intersections on the inflow side surface water, on a long stretch of descent or ascent, in low places with a sawtooth profile of the street channel.
Rice. 118. Reinforced concrete storm water inlet:
1 – sidewalk; 2 – grid; 3 – connecting pipeline
One of the most destructive factors that shortens the life of a roof is water. However, whatever the design of the roof, there are fairly reliable methods that can effectively withstand precipitation and melt water. In this article we will talk about what drain funnels there are for flat roofs and how to install them correctly.
It is worth noting that roof slopes make it easy to cope with the problem of intense rainfall, since water simply drains from them. But in cases where the roof is completely flat, puddles form on it because the moisture does not have time to evaporate. As a result, the waterproofing undergoes gradual destruction, and a layer of dirt accumulates on the roof surface.
Often wind-blown plant seeds germinate in this layer, further destroying the roofing pie. It is the drainage of melt and rainwater into the storm sewer system that is the main purpose of drainage funnels on flat roofs.
What is a drainage system
The term “drainage system” implies a set of devices through which melt and rainwater are collected, transported and removed from the surface of a flat roof.
There are the following types of drains:
- Unorganized, or natural. IN in this case This means that sediments roll down steep slopes. For roofs with large slopes, this method is quite acceptable, but it is absolutely not suitable for flat roofs.
- External. It includes a set of pipes and gutters for water outflow installed on rafters or wind boards. Precipitation enters such drains by gravity and is discharged outside into the storm drain. For flat roofs, this type of construction is applicable only in small buildings.
- Interior. This type of drainage is laid in the thickness of the roofing pie. It is most preferable for flat roofs.
Internal drains for flat roofs
The structure of the internal drainage system suggests the placement of its elements under the insulation and waterproofing layer.
Such a system contains the following components:
- roof funnel – they collect and filter water;
- horizontal pipes - laid under insulation and waterproofing with a slope - for gravity drainage, and without a slope - for vacuum drainage;
- vertical drain pipes - they transport sediment from horizontal pipes to the storm drain.
Depending on the principle of fluid movement, vacuum and gravity drainage systems are distinguished. With a vacuum type of drain, liquid quickly fills the pipe throughout its entire thickness, forming a continuous column of water. As it moves downward, the air mass tends to rise upward, creating a vacuum. The resulting space, as it were, sucks water from the drain funnel, ensures its rapid removal from the roof surface and prevents the accumulation of debris due to the rapid movement of liquid.
Structure of a drainage funnel
By design, a drainage funnel for a flat roof consists of the following elements:
- the lower section, which is laid into the base of the roofing pie;
- sealing gasket, sealing the joint between the upper and lower sections of the funnel;
- the upper section, which passes through the layer of waterproofing and insulation;
- grille – serves to prevent large debris from getting inside drainpipe.
Please note that reliable sealing of the joint between the upper and lower sections of the drainage system funnel is mandatory for the effective operation of the roof. As a rule, it is water getting into the seams of the funnel that causes leaks.
Types of roofing funnels
On sale you can find funnels for flat roofs made of polyvinyl chloride, copper or galvanized steel. The latter are used most often because they differ at an affordable price. Copper products are too expensive for buyers, so they are not in high demand. In addition, they cannot be combined with any roofing covering. Polyvinyl chloride roofing funnels are used on roofs made of ondulin, shingles and soft tiles.
Based on their structure, the following types of products are distinguished:
- Flat. Such products are mounted flush with the roof surface covered with asphalt or tiles.
- Kolpakovaya. This funnel must be equipped with a protective grille to prevent debris and dirt from entering the pipe. The product rises above the surface, resembling a glass or cap.
- With horizontal or vertical release type.
- With heating elements. A heating cable is installed inside such a funnel, which melts the snow and prevents the water from freezing and clogging the drain.
Principles for installing a roof drain funnel
Professional craftsmen have developed some standards for correct installation funnels on soft roof:
- Installation of the device must be carried out in places whose level is below the main surface of the roof. The minimum slope between the funnel and the main roof can be 2º, and over a segment of 50 cm it should increase to 5º. The required slope is created by slabs of insulating material, concrete screed or expanded clay backfill.
- The number of funnels on the surface of a flat roof is determined based on one unit for every 25 m of length.
- Whatever the area of the roof, it must have at least two drainage funnels. They will allow you to withdraw faster a large number of water from the roof if one of the gutters fails.
- The minimum distance between devices is 50 cm, and there must be at least 1 meter to the visor.
Installation sequence on a soft, flat roof
Installation of funnels for removing precipitation from a flat roof is carried out as follows:
- First, the roof is marked, divided into identical geometric shapes. In the central part of each of them, using expanded clay, a layer of insulation and concrete screed, organize a recess. The lower part of the funnel is connected to a drainpipe laid horizontally and mounted at the base of the roofing pie.
- Upon completion of the waterproofing and insulation work, the sealing ring is laid and the two parts of the funnel are connected.
- The upper part of the device is placed between two layers of roofing material, after which it is fixed with a built-up bitumen apron.
- At the end, a layer of bitumen or mastic is applied, and a protective mesh is installed.
- To make sure that the water inlet funnel is installed correctly and tightly, two meters from it, pour a bucket of water onto the roof and check how quickly all the liquid moves into the drain.
It is worth noting that the drainage system, in particular roof drains, require periodic diagnostics and cleaning. This will significantly extend the life of your roof, and will also provide you with rainwater for watering your garden plants.
What kind of roof drainage can there be? Let's find out together what roof drains exist, what they are made of and what technical requirements presented for installation. And finally, I will show you how to install a funnel for a flat roof in 3 options.
Types of funnels and technical requirements
In general, there are 2 types of funnels - for a sloping (pitched) roof and for a flat roof:
- Water inlet for pitched roof built into the gutter system. According to the rules, with a gutter width of 100 mm or more, 1 drain is installed for every 10 m of gutter. The arrangement technology there is simple; the funnel is either screwed to the front board with self-tapping screws, or clings directly to the gutter;
- A storm funnel for a flat roof is usually built into the roofs of multi-storey buildings and large hangars. You can install it yourself, but the technology is much more complicated.
A flat roof is called conventionally. In any case, there is a small slope there (minimum 3%, maximum 10%), it is needed so that the water flows exactly to the place where the funnel is installed.
What are water intakes made of?
- PVC. Plastic reigns supreme in the budget sector. Plastic water inlets are the easiest to install; they are simply glued to the base. But these products break easily from external loads; if you step on them, the funnel will crack;
- Metal plums- the most durable and reliable, but they also have a decent price; metal is used on open terraces and habitable roofs. Most often they are made of stainless steel, but there are also cast iron models, however, they can only be mounted on reinforced concrete floors;
- Combined models- the base is made of metal, and the insides and superstructure are plastic. Combined plums are " golden mean", they are durable, reliable and not as expensive as stainless steel.
Technical requirements
Installation of gutters is regulated by GOST 25336-82. If we highlight the main points of this document, then the main parameters are the throughput of funnels and their number per m2.
As for the quantity, on average, 1 drain funnel with a pipe diameter of at least 100 mm is installed per 200 m² of roof, but with regard to throughput, it is worth mentioning separately.
There are 2 types of hidden roof water intakes - traditional and vacuum:
- In traditional water intakes water flows by gravity, so the diameter of the pipes in them is larger (from 100 mm);
- For vacuum systems pipes are needed in half. The water intake funnel here is two-level and this allows you to fill the pipe completely, as a result a vacuum arises and the water leaves several times faster. If you have ever drained fuel from a car tank with a hose, then you will understand the operation of this system.
Three options for installing a funnel on a flat roof
Roof funnels are different accordingly and they are installed in different ways; we will start with the most progressive installation of a funnel for a siphon or vacuum drainage system at the moment.
Option #1. Funnel for vacuum drain
The Geberit Pluvia company is considered one of the leaders in this direction, so we will consider how to install a water intake funnel for a flat roof from this particular company.
| Illustrations | Recommendations |
| Sectional design. This storm funnel is initially based on an insert; in the photo on the left, the insert is shown with an arrow. To begin with, we need to concrete floor cut a square niche to fit the insert. |
| Attaching the base:
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| Installation of the structure.
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| We mount the cap:
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Option #2. Simpler doesn't mean worse
A siphon roof funnel is often installed in new buildings; there is no point in installing it in old houses, because in addition to the funnel itself, pipes must also be laid according to a special pattern.
For the old gravity roofing system There is a proven old-fashioned method:
| Illustrations | Recommendations |
| Cutting out a niche. This instruction is similar to the previous one, but it is simpler. A niche is cut out around the technological hole; most old houses, as a rule, already have this niche. |
| Mounting the base:
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| Apply bitumen primer. |
| We fasten the structure:
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Option #3. Gutter for light roofing
| Illustrations | Recommendations | |||||||||||||||||||||||||||||||||||
| Laying insulation. Such a roof is called light because the base is made of corrugated sheeting, on top of which dense insulation and a soft roll membrane of the TechnoNIKOL type are already mounted.
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| Setting up a place for a funnel.
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is a roof drainage funnel with a leaf filter, made of polypropylene. Designed to remove rainwater from flat roofs. It is not subject to corrosion and has good mechanical properties and can be used in all climatic zones RF. It is recommended to install one such funnel for every 300-400 m² of roof, but at least one per roof. |
| Specifications | |
| Leg height, mm | 245 |
| Weight, kg | 0,51 |
| Collar size, mm | 380 |
| Inlet D, mm | 110 |
| Funnel “REPAIR POLYVENT”  |
Funnel “REPAIR POLYVENT”- made of polyethylene, which gives them the ability to tightly fit any surface. Used for repairs drainage systems roofs. The funnel foot is inserted into the old roof funnel, or into sewer pipe diameter 100-110 mm. A special insert inside the funnel greatly increases the rate of water intake. The funnels are equipped with a leaf filter. |
| Specifications | |
| Leg height, mm | 240 |
| Weight, kg | 0,57 |
| Collar size, mm | 297 |
| Inlet D, mm | 87 |
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- inserted into old funnels, including cast iron, with a diameter of 60 to 200 mm to prevent leaves and other debris from getting into them. Thanks to the use of a leaf filter, the system internal drain does not require constant maintenance. The insert, which is inserted inside the funnel, significantly increases the volume of water received. |
| Specifications | |
Diameter of protective grille, mm |
160/180 |
Weight, kg |
0,14 |