How to choose a roof drain and install the system correctly. Roof drainage systems, roof drain Why do we need drain drains on a flat roof?

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 this case, it means that precipitation rolls 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 drainage, 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;
a sealing gasket that seals the joint between the upper and lower sections of the funnel;
the upper section, which passes through the layer of waterproofing and insulation;
grate - serves to prevent large debris from entering the 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 the penetration of water 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 are affordable. 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 that prevents 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 the correct installation of funnels on soft roofs:

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 large amounts of water to be removed from the roof more quickly 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 a concrete screed, a recess is created. The lower part of the funnel is connected to a drainpipe laid horizontally and is 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.

HL roof drains with vertical outlet - HL 62, HL 62.1 and others, are used for different types of flat roofs, both unused and used. HL roof drains are used with various roof structures (types) and the filling of the roof pie. They are mounted on existing inversion roofs, insulated flat traditional roofs, roofs made of corrugated sheets (corrugated sheets), “green roofs”, and can be installed on balconies and terraces. HL funnels are designed to drain rain and melt water from roofs into storm drains.

This section presents:

HL funnels with vertical outlet for unused roofs. With leaf catcher. DN - 75, 110, 125 or 160;

HL funnels with vertical outlet for exposed roofs. With grid (150x150 mm) made of stainless steel. DN - 75, 110, 125 or 160;

HL funnels with vertical outlet for roofs made of corrugated sheets. DN - 75, 110, 125. For installation in roofs with insulation thickness - 100-160 mm.

Additional equipment for HL roof drains - extensions, extensions, waterproofing flanges, various leaf catchers, fire couplings.

HL funnels with vertical outlet for unused roofs. With leaf catcher. Sizes - DN 75, 110, 125 or 160.

		Description
		Roof drain with leaf catcher, with thermal insulation, with a stainless steel compression flange (with union nuts/wings), with a vertical outlet. Recommended for waterproofing polymer membranes: EPDM, EPB, ECB (ethylene copolymer bitumen), EVA (ethylene vinyl acetate), PIB (polyisobutylene), etc.
		Like roof drain HL 62, but with electric heating. Self-regulating heating cable. Power - 10-30 W. Voltage - 230 W.
HL 62P		Roof drain with a leaf catcher, with a PVC (polyvinyl chloride) body with thermal insulation for gluing the PVC membrane, with a vertical outlet. Recommended for PVC membranes.
		Like roof drain HL 62P, but with electric heating. Self-regulating electric heating cable with a power of 10-30 W, 230 V.
HL 62 F		Roof drain with leaf catcher, with PP body with thermal insulation for gluing FPO waterproofing membranes. With vertical outlet. Recommended for FPO membranes (PP based).
HL 62.1 F		Like roof drain HL 62F, but with electric heating. Self-regulating electric heating cable with a power of 10-30 W, 230 V.
		Roof drain with a leaf catcher, with a PP body with thermal insulation, with a waterproofing polymer-bitumen sheet 2.5 mm thick and 500 mm in diameter. Recommended for built-up bitumen-based waterproofing materials. With vertical outlet.
		Like roof drain HL 62H, but with electric heating. Self-regulating heating cable. Power - 10-30 W. Voltage - 230 W.
"Universal" funnels for unused roofs with a leaf catcher. With universal connection to steel, cast iron and plastic pipes.
		“Universal” roof drain, with a leaf catcher, with a stainless steel compression flange (with union nuts/wings), with flexible sealing rings, with a vertical outlet. This funnel simply and reliably connects to pipes made of any material (steel, cast iron, plastic). The funnel is inserted inside the pipe and does not require compensation pipes.
HL 69 P		"Universal" roof drain, with leaf catcher like HL 69, but with a PVC flange for attaching a PVC membrane, drain with flexible sealing rings, with vertical outlet. The HL 69P funnel connects simply and reliably to pipes made of any material (steel, cast iron, plastic). It is inserted inside the pipe and does not require expansion pipes. Recommended for waterproofing polymer membranes: EPDM, EPB, ECB (ethylene copolymer bitumen), EVA (ethylene vinyl acetate), PIB (polyisobutylene), etc.
HL 69 H		"Universal" roof drain, with a leaf catcher like HL 69, but with a polymer bitumen sheet, with flexible sealing rings. With vertical outlet. The funnel connects to pipes made of any material (steel, cast iron, plastic). The funnel is inserted inside the pipe and does not require compensation pipes. Recommended for waterproofing polymer membranes: EPDM, EPB, ECB (ethylene copolymer bitumen), EVA (ethylene vinyl acetate), PIB (polyisobutylene), etc.

HL funnels with vertical outlet for exposed roofs. With grid 150x150 mm made of stainless steel. Sizes - DN 75, 110, 125 or 160.

		Description
HL 62 B		Roof drain with thermal insulation, with stainless steel compression flange (with union nuts/wings). With vertical outlet. Recommended for waterproofing polymer membranes: EPDM, EPB, ECB (ethylene copolymer bitumen), EVA (ethylene vinyl acetate), PIB (polyisobutylene), etc.
		Like roof drain HL 62B, but with electric heating. Self-regulating electric heating cable with a power of 10-30 W, 230 V.
HL 62 BP		Roof drain with thermal insulation, with a PVC (polyvinyl chloride) body, for gluing PVC membranes, with a vertical outlet. Recommended for used roofs with PVC membrane waterproofing.
HL 62.1 BP		Like roof drain HL 62BP, but with electric heating. Self-regulating electric heating cable with a power of 10-30 W, 230 V.
HL 62 BF		Roof drain with thermal insulation, with a PP (polypropylene) body for gluing FPO sheets. With vertical outlet. Recommended for used roofs with waterproofing made from FPO membranes (PP based).
HL 62.1 BF		Like roof drain HL 62BF, but with electric heating. Self-regulating electric heating cable. Power - 10-30 W. Voltage - 230 W.
HL 62 BH		Roof funnel with thermal insulation, with a waterproofing polymer-bitumen sheet 2.5 mm thick and 500 mm in diameter. With vertical outlet. Recommended for built-up bitumen-based waterproofing materials.
HL 62.1 BH		Like roof drain HL 62 BH, but with electric heating. Self-regulating electric heating cable. Power - 10-30 W. Voltage - 230 W.
"Universal" funnels for exposed roofs with a grid (150x150 mm) made of stainless steel. with universal connection to steel, cast iron, plastic pipes.
HL 69 V		“Universal” roof drain, with a leaf catcher, with a stainless steel compression flange (with union nuts/wings), with flexible sealing rings, with a vertical outlet. The funnel simply and reliably connects to pipes made of any material (steel, cast iron, plastic). The funnel is inserted inside the pipe and does not require compensation pipes.
HL 69 BP		"Universal" roof drain, with leaf catcher like HL 69 B, but with PVC flange for fixing PVC membrane, drain with flexible sealing rings, with vertical outlet. The HL 69 BP funnel is connected to pipes made of any material (steel, cast iron, plastic). It is inserted inside the pipe and does not require expansion pipes. Recommended for waterproofing polymer membranes: EPDM, EPB, ECB (ethylene copolymer bitumen), EVA (ethylene vinyl acetate), PIB (polyisobutylene), etc.
HL 69 BH		“Universal” roof drain, with a leaf catcher like HL 69 B, but with a waterproofing polymer-bitumen sheet, with flexible sealing rings. With vertical outlet. The funnel connects to pipes made of any material (steel, cast iron, plastic). The funnel is inserted inside the pipe and does not require compensation pipes. Recommended for waterproofing polymer membranes: EPDM, EPB, ECB (ethylene copolymer bitumen), EVA (ethylene vinyl acetate), PIB (polyisobutylene), etc.

Funnels with vertical outlet for roofs made of corrugated sheets. DN - 75, 110, 125. For installation in roofs with insulation thickness - 100-160 mm.

		Description
		Roof drain for roofs made of corrugated sheets, with a leaf catcher, with a stainless steel compression flange (with union nuts/wings), with thermal insulation, with a sliding mounting box (adjustable in height - 100-160 mm). With vertical outlet. Recommended for waterproofing polymer membranes: EPDM, EPB, ECB (ethylene copolymer bitumen), EVA (ethylene vinyl acetate), PIB (polyisobutylene), etc.
		Like roof drain HL 63, but with electric heating. Self-regulating electric heating cable. Power - 10-30 W. Voltage - 230 W.
HL 63P		Roof drain for roofs made of corrugated sheets, with a leaf catcher, with thermal insulation, with a sliding mounting box (adjustable in height - 100-160 mm) like HL 63, but with a smooth PVC flange, for attaching a PVC membrane. With vertical outlet. Recommended for PVC membranes, lightweight corrugated roofing, with insulation thickness of 100-160 m.
HL 63.1P		Like roof drain HL 63 P, but with electric heating. Self-regulating electric heating cable. Power - 10-30 W. Voltage - 230 W.
HL 63 H		Roof drain for roofs made of corrugated sheets, with a leaf catcher, with thermal insulation, with a sliding mounting box (adjustable in height - 100-160 mm) like HL 63, but with a waterproofing polymer-bitumen sheet. With vertical outlet. Recommended for built-up waterproofing materials based on bitumen, lightweight roofs made of corrugated sheets, with an insulation thickness of 100-160 m.
HL 63.1H		Like roof drain HL 63 H, but with electric heating. Self-regulating electric heating cable. Power - 10-30 W. Voltage - 230 W.

Additional equipment for roof drains with vertical outlet HL 62 series

		Description
Extensions for HL 62 series funnels
		An extension element with a stainless steel compression flange and a rubber sealing ring, 345 mm high, is used for a sealed connection with waterproofing, as well as with a roof funnel on flat insulated roofs with a vapor barrier, DN 125
		An extension element with a waterproofing polymer-bitumen sheet and a rubber sealing ring, 345 mm high, is used for a sealed connection with bitumen-based waterproofing, as well as with a roof drain on flat insulated roofs with a vapor barrier, DN 125.
HL 65P		An extension element made of polyvinyl chloride, with a rubber sealing ring, height 345 mm, is used for a hermetically sealed connection with waterproofing made of PVC membranes, as well as with a roof drain on flat insulated roofs with a vapor barrier, DN 125.
HL 65F		An extension element made of polypropylene, with a rubber sealing ring, height 345 mm, is used for a sealed connection with waterproofing made of FPO fabric, as well as with a roof drain on flat insulated roofs with a vapor barrier, DN 125.
HL 65PE		Extension element made of polyethylene (PE), for gluing FPO membranes (PE based).
HL 350.0		An extension element with a profiled flange is used for mechanical fastening (picking) of the second level of waterproofing. Height - 220 mm. DN 145.
HL 350.1		Extension element with stainless steel crimp flange, with PP drainage ring for receiving water flow and installation kit, used for bitumen waterproofing. Height - 220 mm. DN 145.
HL 350.1H		Extension element with waterproofing polymer-bitumen sheet, used to pick up the second level of waterproofing, height 225mm, DN 145
Extensions for HL 62 series funnels
		Extension for roof drains and extension element HL350.0, height 155mm. DN 145.
HL 350.2		HL 350.1 with additional side outlet. DN 40.
Waterproofing flanges for drains of the HL 62 series
HL 84		Waterproofing flange with EPDM membrane 500x500 mm for roof drains.
HL 84.0		Waterproofing stainless steel compression flange with a diameter of 220 mm for roof drains.
HL 84.CU		Waterproofing flange with copper sheet 500x500 mm, for roof drains.
HL 84.E		Waterproofing flange with galvanized steel sheet 500x500 mm for roof drains.
Leaf catchers for hoppers HL 62 series
HL 160		Drainage flange for receiving water flow from waterproofing on an inverted roof. Ø 170 mm.
HL 161		Drain flange HL 160 complete with adapter Ø145 mm to Ø125 mm.
HL 170		Flat leaf catcher for roof drains of the HL 62 and HL 64 series. Ø 170 mm.
HL 175		Stainless steel leaf catcher for roof drains of the HL 62 and HL 64 series. Ø 145 mm.
Fireproof couplings for HL 62 series funnels
HL 850		Fireproof coupling for funnels of the HL 62 series (DN 75), fire resistance limit EI 120, consisting of a metal body with expansion material and a yoke, with a mounting plug. Applicable only on outlets DN 75.
HL 870		Fireproof coupling for roof drains of the HL 62 series (DN 110), fire resistance limit EI 45, consisting of a metal body with expanding material and a yoke, with a mounting plug. Applicable only on outlets DN 110.

The main enemy of any roof is water, the destructive effect of which leads to a reduction in the service life of the roofing material and leaks. Gable, hip and even single-pitched types of roofs have something to resist melt and rain water.
These are their slopes, thanks to the slope of which moisture, without lingering on the roof, slides down. Flat roofs are less protected; puddles accumulate on a flat surface and do not have time to dry.

Stagnant water methodically destroys the waterproofing layer; in addition, dust blown by the wind settles in them, forming a swampy substrate. Plant seeds that fall into this “soil” germinate and destroy the roofing pie with their roots. To avoid extending the service life, they are equipped with a drainage system that drains water from its surface into the storm drain.

Flat roof drainage system

The drainage system of a flat roof is a set of elements that collect, transfer and discharge water that appears on the roof surface as a result of precipitation or melting snow. equipped with the following types:

Disorganized. It consists in the fact that the water simply slides off steep slopes. This method of self-draining is used in private houses with pitched roofs, but is not suitable for buildings with a flat roof.
External. Consists of a gutter and downpipes fixed to the wind dock or rafters. By gravity, due to the slope of the roof, water is removed from the slopes and drained into a drainage ditch or storm drain. External drainage is used to drain water from a small flat roof, in particular for utility buildings.
Interior. A characteristic feature of the internal drain is that it is laid inside the roofing pie. It is designed taking into account the specifics of flat roofing.

Internal flat roof drainage

They are not placed outside, but under layers of waterproofing and insulation. It consists of:

Drainage funnels installed on the roof surface in low places constructed during slope. The function of funnels is to collect and filter melt and rain water falling on the roof.
Horizontal drainpipes, which are installed under a layer of waterproofing and insulation on a slope, if a gravity drain is installed, or without a slope, if a vacuum drain.
Vertical drainpipes that collect water flows coming from horizontal pipes and drain into storm drains.

Depending on the method of moving water into the drainage system, there are gravity and vacuum types. The principle of operation of a vacuum drain is that precipitation completely fills the pipes, creating a column of water, which, when moving downwards, air first rises upward, creating a vacuum environment, and then carries water with it from the drain funnel, as if sucking it in. In areas with heavy rainfall, experienced roofers recommend installing a vacuum system, which quickly copes with large volumes of water, and even self-cleans due to its rapid movement through the pipes.

A drainage funnel on a flat roof is responsible for collecting and receiving water accumulating on the surface. It consists of:

The lower part, which is mounted into the base of a flat roof.
A seal that hermetically connects the upper and lower parts of the drainage funnel.
The upper part, passing through the thickness of the insulation and waterproofing.
A protective grille, which is located above the roof surface and protects the drainage funnel from the penetration of large debris and the formation of blockages.

The tightness of the connections between the elements of the drainage funnel is a prerequisite for the effective operation of the drainage system. When examining a flat roof after a leak was discovered, in 70% of cases the problem was water penetration between the joints of the funnel parts.

Types of drainage funnels

The roof drain can be made of galvanized metal, copper or polyvinyl chloride. Galvanized copies are used more often than others, due to their affordable price. Copper funnels have not gained popularity due to their exorbitant cost, especially since they are not compatible with all roofing materials. Products made of polyvinyl chloride are excellent for installation on soft tiles, shingles, and ondulin.

The following types of drain funnels are available in specialized stores:

When installing gutters, professional roofers adhere to the following principles:

Place funnels in places located below the main roof level. The slope between the base and the funnel should be at least 2 degrees, and at a distance of 50 cm increase to 5 degrees. The slope is set when tilting with insulation slabs, expanded clay or concrete.
Gutter funnels are distributed evenly over the surface of a flat roof at the rate of 1 piece per 25 meters of length.
Regardless of the roof area, the minimum number of drainage funnels is two. Since in the event of a clogged drain or during heavy rainfall, the second one will insure a funnel that is out of order or cannot cope with a large volume of water.
The smallest permissible distance between drain funnels is 50 cm. And from the edge of the roof - 1 m.

Installation procedure

Install drainage funnels on a flat roof as follows:

The drainage system, including funnels, must be periodically inspected and cleaned so that an unexpected downpour does not lead to a roof collapse. A well-organized drain will not only extend the life of the roof, but will also become a source of water for irrigation if you are concerned about preserving natural resources.

Video instructions

Today, buildings with a flat roof, familiar to industrial and multi-story buildings, are increasingly found in private housing construction. Such a roof makes it possible to obtain additional space for arranging a terrace, sports ground, swimming pool, or garden. To ensure the protection of the roofing covering from destruction under the influence of moisture, it is important to provide an effective system for draining melt and rainwater, and take care of the correct installation and heating of water intake funnels.

Choosing a drainage system

For flat roofs there are two options for drainage systems:

Traditional (requires the installation of a large number of funnels, water flows through the system pipes by gravity).
Gravity-vacuum (features high throughput with a minimum number of communications).

Traditional internal drain. For its effective functioning, it is necessary to properly slope the roof, with funnels mounted at the lowest points. The number of water receivers depends on the size of the roof. The water intake elements are connected using pipes to a vertical drain pipe, through which water from the roof enters the sewer system. It is important to install horizontal pipeline elements with a slope to ensure free drainage of water by gravity.

Gravity-vacuum system. For more than 30 years, it has been actively used in many countries in Europe and the world due to its high efficiency and efficiency. The principle of operation is based on the fact that in a system equipped with a siphon, a vacuum environment occurs, due to which water is sucked from the surface and moves through the pipes at high speed. The advantages of the system include:

the flow has a high speed;
simplified installation (fewer funnels and communications are required, pipes do not need to be installed at a slope, since water moves through them under air pressure);
light weight (does not create additional impact on the roofing system);
cost-effectiveness (funnels and pipes of smaller diameter are used in comparison with a traditional system without loss of productivity);
ability to self-clean (the throughput of the system does not change over time).

For comparison: a vacuum system funnel with a horizontal outlet of 75 mm is capable of passing up to 15 liters of liquid in one second. To provide the same throughput of a traditional drain, you will need to install a funnel with a horizontal outlet of 200 mm.

During heavy rainfall, a large volume of water can accumulate on a flat roof, which the drainage system cannot cope with. To avoid collapse of structures due to excessive load, it is necessary to install a special additional drainage system - a storm drain. It can also serve as the main drain if the latter becomes clogged.

Selecting a drain funnel

Funnels for arranging internal drainage are made of polymers, metal or a combination of materials. When choosing a product, it is important to consider the type of material that is used as roofing on the roof. Metal funnels are used for installation on roofs covered with sheet metal. Polymer products are suitable for installation on soft roofs.

A flat roof drain can be round or rectangular, with a horizontal or vertical outlet. The choice depends on the installation location and roof features. The products differ in design, but in any case it is possible to rigidly attach the funnel to the base of the roof and ensure reliable waterproofing of the fastening point.

Funnels with a metal flange are fixed using a clamping method using stainless steel fasteners. Funnels with a polymer flange equipped with a sealing collar are attached using an adhesive method.

The drainage system must be protected from clogging. To prevent large debris from entering the drain, funnels are equipped with protective covers or nets. Products with flat covers with slots are used on existing roofs. The lids can support the weight of a person. If you plan to create a “green” roof, it is best to use funnels with a leaf filter in the form of a mesh cap.

The principle of placement of water intakes

Water receivers must be installed in the lowest areas of the roof. It should be evenly distributed over the surface. To prevent the formation of stagnant puddles on the roof, the slope of the surface towards the funnel should be at least 2%, while at a distance of about half a meter to the drain funnel, the slope should be increased to no less than 5%. Changing the slope is achieved by leveling the screed or reducing the thermal insulation layer.

The number of water receivers is calculated as follows: each funnel should have no more than 200 square meters. m of surface, the distance between funnels is at least 50 cm. The minimum diameter of the pipe is 10 cm. Regardless of the size of the roof, at least two funnels must be installed on it, or one funnel and a storm drain. This will avoid flooding if the water inlet is clogged.

When calculating the number of water receivers and their parameters, the intensity and frequency of precipitation in a given region is taken into account.

Construction of an internal drainage system: installation of funnels

First option. The most practical to use are composite funnels, the body of which consists of two parts. Due to a certain dynamic reserve, such funnels, unlike rigid structures, compensate for movements of the insulation.

The installation of a water receiver begins with installing the lower part of the composite funnel into a prepared passage hole cut in the roof slab. The lower part is inserted into the drainpipe, and the fasteners should not be rigid in order to avoid damage to communications due to temperature deformations.

The outer part of the funnel to create an internal drain is installed on top, passing through the roofing carpet and a layer of insulation, it is inserted into the lower part. There is an o-ring seal between the parts of the funnel. The plastic apron of the upper part should be laid on the lower lining layer of roofing material. An additional lining layer is mounted on top of it and a bitumen apron is fused as the next layer of waterproofing. An outer layer of roofing material is mounted on top of the apron, which is inserted into the funnel bowl and secured with a pressure ring and stainless steel fasteners. At the last stage of the device, a protective grille is installed on the funnel.

Second option. The installation of a water receiver with a pressure flange is carried out in several stages. It is recommended to attach the funnel not to the insulation, but to wooden blocks of suitable cross-section, securely fastened to the base of the roof. The funnel is tightly installed in the hole (it must be rigidly fixed), a rubber-bitumen sealing gasket is installed between the flat side of the funnel and the pressure flange, which is laid under the roofing carpet. At the next stage of the device, the metal clamping flange is fixed with special stainless steel fasteners. For installation of fasteners, holes are provided in the flange, sealing gasket and funnel side. At the end of installation, the cover is secured.

The principle of construction of water intake funnels depends on the configuration of the product and the type of roofing. When installing, you must follow the manufacturer's recommendations.

Heating of water receivers

Drain funnels in winter in cold climates need to be heated to prevent the formation of ice plugs in the pipe and adjacent sections of the horizontal pipeline. The freezing depth reaches one and a half meters, so it is recommended to provide heating for these elements of the drainage system.

Freezing of water in pipes and pipes leads to flooding of the roof surface during thaws and snow melting, since ice hidden from the sun's rays surrounded by a thermal insulator (a layer of insulation in the roofing pie) is the last to melt.

Today, funnels for flat roofs are available for sale, already equipped with a built-in heating system. But by themselves they will not solve the problem: in this case, the ice plug will grow on the outside. Of course, it will melt faster than the internal one, but it can also create a serious problem by cutting off the flow of water to the drain.

To ensure that the water drainage system functions properly all year round, install a heating system for the area around the funnel using a self-regulating heating cable for the roof. In this case, the possibility of blocking the drain with ice is eliminated

The drainage funnel for a flat roof (fitting) is the main element of the external drainage system. Through it, rain or melt water flows into pipes, which can be installed outside or inside the house, and then into the ground, drainage tank or sewer system. For free drainage of water, the water intake is mounted in the lowest place of the roof. In this case, the minimum slope in its direction is 2°.

Drainage funnel device

Today on the market you can find various types of drainage fittings, which differ in the material of manufacture, design, build quality and cost. The standard design of the water intake consists of the following elements:

body - made of galvanized steel, cast iron or plastic (mounted directly into the roof);
grid - is a filter element that protects the drain system from contamination;
downpipe - used to connect the fitting to the drainpipe;
O-rings and gaskets - allow you to achieve maximum tightness at the junction of the product with the roofing material, thereby preventing moisture from getting under the roof;
thermal cable - considered an additional element that increases the efficiency of drainage during the cold season, preventing water from freezing near the outlet.

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Types of water intake fittings

Roof drains are classified according to the following parameters:

Material of manufacture. Modern water intakes are made from cast iron, galvanized, plastic or a combination of several materials. When choosing a funnel based on this feature, you need to take into account what the roof itself is made of. So, for sheet flooring, the best option is a metal fitting, for a concrete floor - cast iron, and for a soft roof - plastic.
Form. Funnels can be flat or bell-shaped. The first type is installed level with the roof plane. Such products need to be periodically cleaned of leaves, branches and other debris, so they can only be installed on roofs that are in use. Bell-shaped products are equipped with a protective mesh that protects the water intake from contamination.
Design. Fittings for flat roofs can be manufactured as a single piece or consist of two parts connected by a flexible pipe. The second type is used on movable roofs (non-ventilated or wooden). Due to the fact that the components of the funnel can move relative to each other, the integrity and tightness of the product is maintained with any movement of the base.
Bandwidth. Depends on the diameter of the outlet. When choosing a capacity, you need to consider the roof area and the annual rainfall experienced in your area.
Method of attachment to the base. A drainage funnel for a flat roof can be attached using a crimping seam or a flexible apron made of roofing felt or thick film. Seam fastening is universal because it can be used with any roofing material.

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Funnel installation procedure

The first step is to choose where to install the fittings. These products are mounted at the lowest points of the roof. At the same time, they must be evenly distributed over the entire surface of the ceiling, which will allow achieving high efficiency of the drainage system.

After choosing a place for the fitting, the lower part of the product is installed in the hole prepared in the ceiling. The fixation of the funnel to the base should not be rigid in order to exclude the possibility of its damage due to temperature deformations. Next, insulation and waterproofing are laid. The top of the funnel is then attached to the bottom. To improve the tightness, an o-ring seal is additionally mounted. The film apron of the fitting is placed between the lower and upper layers of roofing felt and secured with molten bitumen mastic.

To avoid the occurrence of stagnant puddles, it is necessary to organize a slope towards the drain holes of at least 2°.

This can be done using a screed or laying a thermal insulation layer of different thicknesses. It should be taken into account that it is not recommended to place the drain near support columns, since deformation shifts are often observed in these places, which can negatively affect the service life of the drainage system. Funnels for flat roofs are installed at the rate of 1 piece. per 150 m 2 of flooring, but their number must be at least two. For example, for a roof with an area of 70 m2 you will need 2 fittings, for 100 m2 also 2 pieces. If the roof area is more than 300 m2, then for normal operation of the drainage system, 3 water intake points should be used.

At the last stage of work, the finishing layer of roofing material is laid, which is inserted into the fitting bowl and secured with a clamping ring. After installing the protective cap, the functionality of the entire structure is checked. To do this, pour a bucket of water near the water intake and observe whether all the liquid gets into the drainage system.