Flat roof installation with internal drainage and installation of a drain funnel

Calculation of components

Based on the size and shape of the roof, you can independently calculate: how many pipes, gutters, brackets and other parts of the drainage system will be needed.

Based on the size of the roof, choose the diameter of the gutters:

• If the roof area is less than 50 m2, gutters 100 mm wide and pipes 75 mm in diameter are used.
• Up to 100 m 2, 125 mm gutters and 87 mm pipes are used.
• More than 100 m 2 - gutters 150 mm and pipes 100 mm (it is allowed to use gutters 190 mm and pipes 120 mm).

In the case of a complex roof structure, gutters and pipes are determined by the largest projection of the roof part.

The area of ​​the roof, consisting of parts, is 160 m 2 . Considering that one drain pipe is enough to serve 100 m 2 of the roof in the projection, for the roof from the example, you will need 2 drain pipes located at the corners of the house. The number of funnels corresponds to the number of pipes, i.e. - 2 pieces.

The number of vertical pipes is determined depending on the distance from the cornice to the blind area. 30 cm are subtracted from this distance - the height of the drain elbow above ground level.

For example, the height to the cornice is 7.5 m. Then 7.5 m -0.3 m = 7.2 m.

On each side, we need 3 pipes of 3 m each, which means there are 6 pipes on both sides.

The number of clamps will be equal to 5 for each side (between the elbow and the pipe, between the pipe and the ebb, and between the pipes) and, accordingly, 10 pcs for the entire roof.

Calculation of the number of gutters

The most commonly used gutter size is 3 meters. The length of cornice A and cornice B is 10.3 m. So we need:

• On eaves A - 4 gutters (3m + 3m + 3m + 1.3m). At the same time, we will have another 1.7 m of unused gutter.
• On cornice B - 3 gutters and the remainder (1.7 m) from cornice A.
• For cornices C and D we use 2 gutters each, that is 4 pcs on both sides.
• In total, 11 gutters of 3 m for the entire roof.

The number of gutter corners corresponds to the number of roof corners, in our example there are 4.

Calculation of the number of brackets and gutter locks

Brackets are installed at the rate of 1 piece for about 50-60 cm. We accept 50 cm and make calculations.

Summing up the numbers in the last column, we find out that in order to fix the gutters, we need 58 brackets.

The number of locks between the gutters is equal to the number of joints. In our case, this is 16 pieces.

The number of ebbs (marks) is equal to the number of funnels. In this case, knees are needed 2 times more for each funnel. Then for 2 funnels you need:

• 4 knees;
• 2 low tides.

If the facade is not even, but has protrusions, it is necessary to purchase knees to bypass it. The figure below will help determine their number.

List of required items

In total, for this drainage system you will need:

• Gutter (3 m) - 8 pcs.
• Gutter (2.5 m) - 2 pcs.
• Gutter (1.3 m) - 2 pcs.
• Gutter lock - 16 pcs.
• Gutter corner - 4 pcs.
• Bracket - 58 pcs.
• Knee - 4 pcs.
• Drain elbow (mark) - 2 pcs.
• Pipe (3m) - 6 pcs.
• Funnel - 2 pcs.
• Clamp (with pin) - 10 pcs.

Pro tip:

Systems of internal cold and hot water supply

20. Internal gutters

20.1. Internal drains should ensure the removal of rain and melt water from the roofs of buildings.

Note. When installing internal drains in unheated buildings, measures should be taken to ensure a positive temperature in pipelines and drain funnels at a negative outdoor temperature (electric heating, heating with steam, etc.). The feasibility of installing heated internal drains should be justified by a feasibility study.

20.2. Water from internal drainage systems should be diverted to external rainwater or general sewage networks.

Notes: 1. When justified, it is allowed to provide for the removal of water from the system of internal drains to the industrial sewerage system of uncontaminated or reused wastewater.

2. It is not allowed to divert water from internal drains to domestic sewerage and connect sanitary appliances to the system of internal drains.

20.3.In the absence of rainwater drainage, the release of rainwater from internal drains should be accepted openly into flumes near the building (open outlet); at the same time, measures should be taken to prevent erosion of the earth's surface near the building.

Note. When arranging an open outlet on a riser inside the building, a hydraulic seal should be provided with the removal of melt water in the winter season to the domestic sewer.

20.4. At least two drain funnels must be installed on the flat roof of the building and in one valley.

Drainage funnels on the roof should be placed taking into account its relief, the allowable catchment area per one funnel and the building structure.

The maximum distance between the drain funnels for any type of roof should not exceed 48 m.

Note. On flat roofs of residential and public buildings, it is allowed to install one drain funnel for each section.

20.5. Accession to one riser of funnels located at different levels is allowed in cases where the total estimated flow rate for the riser does not exceed the values ​​\u200b\u200bgiven in Table. 10.

Drainpipe diameter, mm

20.6. The minimum slopes of branch pipelines should be taken: for overhead pipelines 0.005, for underground pipelines - in accordance with the requirements of Sec. eighteen.

20.7. To clean the network of internal drains, it is necessary to provide for the installation of revisions, cleanings and manholes, taking into account the requirements of Sec. 17. On risers, revisions must be installed on the lower floor of buildings, and if there are indents, above them.

Note. With a length of suspended horizontal lines up to 24 m, it is allowed not to provide for cleaning at the beginning of the section.

20.8. The connection of drain funnels to the risers should be provided with the help of expansion sockets with an elastic seal.

20.9. Estimated rainwater discharge Q, l/s, from the catchment area should be determined by the formulas:

for roofs with a slope up to 1.5% inclusive

for roofs with a slope over 1.5%

In formulas (34) and (35):

F — catchment area, sq.m;

— rain intensity, l/s per 1 ha (for a given area), lasting 20 minutes with a period of a single excess of the design intensity equal to 1 year (accepted in accordance with SNiP 2.04.03-85);

- rain intensity, l / s from 1 ha (for a given area), lasting 5 minutes with a period of a single excess of the calculated intensity equal to 1 year, determined by the formula

here n is a parameter accepted in accordance with SNiP 2.04.03-85.

20.10. The estimated flow of rainwater attributable to the gutter riser should not exceed the values ​​\u200b\u200bgiven in Table. 10, and for a drain funnel is determined according to the passport data of the accepted type of funnel.

20.11. When determining the calculated catchment area, an additional 30% of the total area of ​​the vertical walls adjacent to the roof and rising above it should be taken into account.

20.12. Drainpipes, as well as all discharge pipelines, including those laid below the floor of the first floor, should be designed for pressure that can withstand hydrostatic head during blockages and overflows.

20.13. For internal drains, plastic, asbestos-cement and cast iron pipes should be used, taking into account the requirements of paragraphs. 17.7, 17.9.

On horizontal overhead lines in the presence of vibration loads, it is allowed to use steel pipes.

Installation of the curly part and drain pipes

Laying the drain provides for the installation of pipes from top to bottom, while the elbow, coupling and drain are installed with a socket to the top.

Installation is done like this:

1. A part of a straight pipe of at least 60 mm is inserted into the knee-knee connection (depending on the distance between the frontal board and the wall).
2. Next, the necessary figured part is assembled, into which the upper end of the pipe is inserted.
3. The system is attached to the wall with clamps, the distance between which is up to 1.8 m.Only one clamp is fixing, the second is a guide. In some systems, the manufacturer recommends the use of clamps - expansion joints. The clamp is attached under the connector.
4. The pipe is set strictly vertically using a plumb line.
5. A drain elbow is installed on the lower end of the pipe, fixed with clamps (the lower edge is at a distance of 25-30 cm from the blind area).
6. If there is a drainage system or a storm water inlet, then the lower end of the pipe goes there. The pipes are connected using a coupling (connector).
7. Each subsequent pipe is inserted into the connector installed on the previous one.
8. A clamp is attached under each connection.

1. Depending on the design features of the installation site, an elbow of the desired shape or a coupling is attached to the funnel. In the case of a roof protrusion beyond the facade, two elbows and a pipe segment are used. If the roof is without a ledge, then a coupling is used.

Installation of roof drains is carried out taking into account the compensation of thermal expansion. For this function, manufacturers use compensation gaps. So on pipe connectors in some systems there are assembly lines. The edge of the pipe is set along these lines, depending on the air temperature at the time of installation. Silicone-treated seals allow smooth sliding of the elements during expansion. When using a pipe connector, leave an air gap of at least 0.6-2 cm.

Pro tip:

It is not recommended to assemble the drainage system at t o C below -5.

This completes the installation of the drainage system. It is necessary to revise all installed elements. If the configuration of the drainage system is fully consistent with the project, calculated and installed according to the manufacturer's recommendations, then all the water that enters the roof will only leave through the pipes, without splashing or overflowing over the edges of the gutters.

At the end of each season, it is advisable to inspect and flush the system (using a hose with water). When clearing emerging congestion (leaves, debris), do not use sharp metal objects.

The drainage system is one of the main protective measures that contributes to the extension of the operation of roofing materials, the facade and foundation of the building. Correct and competent calculation of the gutter system of the roof is the key to long-term and reliable operation of the entire building as a whole. Knowing the basic principles of calculating the components of the drainage system will help optimize the cost of its arrangement.

Depending on the type, size and slope of the roof, the drainage system can be of several types.
:

• organized;
• unorganized.

The calculation of the external is performed taking into account the following requirements
:

• hanging or wall gutters must be installed on roofs with a slope angle of at least 15°;
• longitudinal is observed at a level of at least 2%;
• gutters must have sides with a height of more than 120mm;
• the distance between the drain pipes is no more than 24 meters;
• the diameter of the drainpipe is taken at the rate of 1.5 cm 2 of the section per 1 m 2 of the roof.

These rules are valid for drainage systems in climatic zones with a low probability of water freezing.

• riser;
• funnel;
• outlet pipe;
• release.

Depending on the required configuration and functions performed, the water drainage system can be supplemented with a variety of accessories and components.

What is a flat roof with an internal drain and why is it needed

The absence of roof slopes deprives the roof of a natural slope in order to to carry out precipitation. First of all, this applies to rain, melting snow or hail.

In such cases, buildings can be equipped with internal or external drains.

The device for internal water flow is a rather complex system when compared with external means designed for the same purposes.

But due to the mass of advantages, the owners of various structures choose exactly the system that is located inside the house. Such a solution to the issue of removing atmospheric precipitation can be compared to how water flows down from an ordinary bath.

The fluid finds the only path of least resistance, where it is directed through the flow. First, it enters the sewer pipe, after which it enters the sewer riser. In some cases, it is possible to make the system in such a way that water will be collected in a special reservoir, from which it can be used as a technical fluid.

The main advantages of flat roofs with internal drainage are:

• increasing the aesthetics of the building itself, since pipes or other precipitation drainage systems will not be visible on its facades;
• no freezing of sewage in winter, as they are hidden inside and warmed by the building itself;
• higher water removal efficiency.

IMPORTANT!

The biggest problem that owners of flat roofs with internal drainage face is clogging. Cleaning in such cases is very difficult. But at the moment, special technical means have been created that maximally prevent the occurrence of such situations.

It is also very important to consider the internal drainage before construction begins or before roofing begins. After the construction is completed, it is possible to carry out the installation of an atmospheric water drainage system only in cases where part of the house is dismantled

Drainage device

What is internal drainage

You can characterize the internal drain in just one sentence. It is installed on a flat roof, while the external one is mounted on a classic sloping roof.

Such a drain received its name mainly due to the fact that it is part of the structure itself, and not a separate system from it.

Also, the difference between external and internal drains can be understood at the design stage of the system. If we take a roof project, then the internal drain is outlined within its perimeter, and the external drain is behind them.

Relatively recently, the internal drain was used only to protect apartment buildings, because it was in this type of construction that a flat roof was common. Today, more and more people are choosing a flat roof when building private houses. Along with this, the internal drain became more popular.

The main tasks of such a drain, like any other similar system, are to protect the roof and facade of the building from the negative effects of moisture. Without a properly installed such a drain, the structure can last much less than the prescribed period. In addition, it will require constant cosmetic repairs, because facing materials become unusable much faster than the main ones.

In a building with a flat roof, the drain is even more important, because it itself does not have any structural features that allow it to be protected from rain and melt water. In standard types of roofing, this is achieved by slope and covering the roof itself.

If you have noticed, all materials used for roofing usually have a corrugated surface.

In the internal drain, all the same elements are used as in the external one, but they can differ significantly from them in design and their functions.

This is interesting: How to make a drain: we learn all the nuances

Calculation of pipes, number of gutters and fasteners

Before proceeding with the installation of an external drainage structure, it is necessary to examine the house for features in its architecture. It is impossible that the drainage system violated the appearance of the household. If it does not fit into the facade of the building, it is better to place it on the back side. For this purpose, special accessories available on the market are used.

It is necessary to begin the calculation of the drainage system by determining the area of ​​\u200b\u200bthe roofing surface from which precipitation will be removed. For this, simple geometric formulas are used. It is generally accepted that a 100 mm downpipe is able to cope with the removal of liquid from a roof area of ​​​​up to 220 m².

The size of the section of the gutters is determined taking into account the angle of the slope. The steeper the slope, the higher the side of the gutter should be. This is due to the increase in the area from which precipitation is collected.

To determine the number of hooks for fastening, use the formula:

N=(L - 0.3):(0.6 +1), while:

N is the desired value;

The number of downpipes is found using the formula:

N pipes \u003d (0.2 × N eaves - N bend + L insert): L pipes, where:

H cornice - the distance between it and the ground;

H bend - the height of the pipe bend;

L inserts - the length of the funnel insert;

L pipes - the length of the pipe (usually 3 or 4 meters).

To secure each piece of downpipes, use at least 2 clamps.

How to calculate gutters for a flat roof

Flat roofs are gaining popularity in private construction. Often these are exploited roofs. The drainage system in such houses is internal - storm and melt water enters the water intake funnels installed on the roof, from them into the drains, and then into the rain sewer pipeline.

Flat roof. No drains. During the rainy season, you can release turtles into this pool, but sooner or later the roof will leak, and then you will have to repair not only the roof, but also the ceilings (and save innocent animals)

According to SP 32.13330.2012, when developing a project, it is necessary to consider the possibility of cooperating sewer systems. In the same code, mandatory consideration of the use of surface water for irrigation is prescribed, which is quite possible if a septic tank with several chambers for multi-stage treatment is installed on the site (treated effluents are used for irrigation). That is, nothing prevents the internal pipeline of the drainage system from connecting to the sewer (this is the cooperation of systems). The pipeline is located in the attic space (if there is none, ceiling laying is acceptable). Funnels are connected to it. The pipeline is connected to the riser. To connect parts, shaped elements equipped with sealing rings are used. Be sure to include revision and cleaning. Another option (not the best) is standard gutters if the roof has a parapet. Holes are made in this parapet, pipes are brought to them.

Outdoor drainage device

• no matter how flat the roof is, a slope (towards the funnels) of 1–2% is necessary;
• the drainage collector is installed in the buried part of the building (or underground: the structures are insulated underground; open laying is allowed in the room), the spillway is connected to the sewer there;
• allowable pipe sizes: length - 700–1380 mm, diameter - 100, 140, 180;
• the diameter of the pipes is determined on the basis that 1.5 cm2 of the section removes water from the square of the roof;
• the number of funnels is determined on the basis that 1 cm2 of the cross section of the water intake is able to divert water from 0.75 m2 of the roof;
• funnels should be in insulated (heated) places;
• the inclusion of funnels must be completely sealed - a waterproofing carpet is glued to the sides of the funnels;
• the usual number of funnels is one per roof section;
• water can be discharged into the rain sewer without combining networks.

Water will find a hole - however, it is better when this hole is planned and in the right place.

How not to do it in any case (it’s just that no one has filed a lawsuit against the municipality)

Some owners of houses with flat roofs with a slight slope (barely allowing water to drain by gravity) are tempted to arrange an unorganized drain. A hole is made in the parapet - water escapes through it.We strongly recommend that you do not engage in amateur activities of this kind: even if there is a powerful blind area below, and close to it are rain sewer trays. The water damages the facade so much that the famous "brezhnevka" in comparison with the damaged walls will seem like a masterpiece of architectural thought. The internal drainage system is not at all the prerogative of flat roofs - it is quite possible to connect it to the gutters of a pitched roof, but this task is for professionals. Such a system must be installed at the construction stage, having previously developed the project in parallel with the rest of the project documentation.

Calculation of the number of funnels of the external drain, pipe diameter

There is a gable roof, the length of the slope is 24 m, the distance from the eaves to the ridge is 10.5 m. It is required to calculate the number of funnels and the diameter of the downpipes for each slope. There are conflicting data on the number of sinkholes and the diameter of the waters. pipes:1- SP 17 Roofs 9.7 “In case of an external organized drainage of water from the roof, the distance between the downpipes should be taken no more than 24 m, the cross-sectional area of ​​the downpipes should be taken from the calculation 1.5 cm2 per 1 m2 roof area. Calculation: For a gable roof with an area of ​​​​one slope 24 * 10.5 \u003d 252 m2 With a pipe with a diameter of 10 cm - the area of ​​\u200b\u200bthe cross. pipe section: S \u003d Pi * R (squared) \u003d 3.14 * 25 \u003d 78.5 cm2 Required. cross-sectional area of ​​​​downpipes: 1.5 * 252 = 378 cm2 Number of pipes with a diameter of 10 cm: 378 / 78.5 = 4.81. Those. 5 pipes2.- The vast majority of sources on the Internet talk about a smaller number of pipes: either about 100 m2 per 1 pipe. It turns out 252/100=2.52=3 pipes Or they provide tables, according to which in general 2 pipes with a diameter of 10 cm. In the technical documentation of the Grand Line company (they refer to the calculation according to DIN EN 612-2005), the Grand Line system 150mm-dia. funnels/100mm-dia. pipes - designed for 178 m2Those. 2 pipes are enough for 250 m2 Where is the truth? in the joint venture or in the vast majority of Internet sites? How many drains to take?

Last edited by MaxKad on 02/08/2017 at 21:34.

Where is the truth? in the joint venture or in the vast majority of Internet sites? How many drains to take?

I believe that the truth is in the joint venture, but not only in one joint venture 17.13330.2011, but also in the joint venture 30.13330.2012 and joint venture 32.13330.2012: 9.2. The number of funnels, depending on its throughput, roof area and construction area, is determined according to SP 30.13330 and SP 32.13330. I believe that the number of funnels, at least internal, at least external drain, and the diameter of the pipe (riser) primarily depends on the estimated rainwater flow rate (l / s), and not just on the area of ​​\u200b\u200bthe roof. In SP 17, for the external drainage, a too approximate calculation method is given, which does not take into account the intensity of rain for a particular construction area. (clause 8.6.9 of SP 30.13330.2012).

DIN EN 612-2005 is good, but “what is good for a German is death for a Russian” (c) Gutter manufacturers have the right to refer to anything, especially if they provide a guarantee to the buyer that there will be no overflow during rain. And the designer must justify his decisions himself, referring to the norms in force in the country.

__________________Architecture is a diagnosis.

The choice of material of manufacture which gutters to install

Galvanized steel products should not be considered for installation on a residential building. The low cost of materials will not make the installation cheaper: installation will take a lot of time, and it is almost impossible to hermetically assemble handicraft-made parts. Steel covered with a thin protective layer of galvanization will begin to rust in 2 to 3 years, you will have to install a new system. Modern budget drains are made:

Made of plastic - PVC.

Made of metal with polymeric protective coating.

Aesthetic appearance and reasonable price: the advantages of plastic gutters

Plastic gutters: in what cases is it worth installing a PVC system

Inexpensive plastic parts can last for decades without breaking. Components are made from polyvinyl chloride - a polymer based on acrylic resins. Gutters and pipes are ultralight in weight, easy to transport and do not require special skills during installation.

Elements of the plastic system

Plastic systems are perfect for installation on low one-story residential buildings, outbuildings, garages, country houses.Mounted on old roofs with fasteners on the wind board. Manufacturers recommend PVC for organizing a drain on the roofs of attic floors: plastic trays are almost silent, unlike metal ones.

The material is quite fragile and does not differ in strength. Subject to mechanical damage, especially at low air temperatures. Therefore, when choosing a system for installing a plastic roof drain in a region with a cold climate, it is worth considering the simultaneous installation of a heating cable. Roofing is equipped with the obligatory presence of snow retainers in order to reduce the risk of damage to the drain when snow melts.

Gutters made of metal with a polymer layer belong to the middle price category. Parts are made of steel alloy, several layers of polymer are applied on top to protect the box from water. When calculating the drainage system, the installation price should also be taken into account: it is difficult to install metal-plastic parts on your own. The gutters are quite heavy; it is impossible to mount the trays alone at a height.

Metal-plastic drain: details

When assembling, you need a special tool and skills to work with metal: metal-plastic parts cannot be cut with a grinder or a nozzle on a drill. The polymer coating is sensitive to temperature; when overheated, it exfoliates. Also, metal-plastic products require careful handling during loading and transportation: the surface must be closed. Scratches on the polymer are conductors of water to the metal base, respectively, rust quickly forms at the points of damage.

Metal-plastic is the best choice for:

Drainage assembly for country cottages of large area and height.

Installation of trays on rafters - it is allowed to increase the interval between fasteners up to 90 cm.

Installations in difficult climatic conditions.

How is the drainage system on a flat roof

The main purpose of the roof drainage system is to drain water that forms on the surface of the roofing as a result of precipitation in the form of rain, as well as when snow melts in the autumn-spring period of the year.

Gutter roofing systems are of three types, these are:

• outdoor unorganized - when water drains from the surface of the roof spontaneously, due to its slope to one side;
• outdoor organized - assumes the presence of gutters for collecting water, located along the edge of the roof, with its subsequent transfer to downpipes mounted on the facade of the building;
• internal - consists of receiving funnels placed on the surface of the roof, serving to collect water by means of slopes made on its surface, and vertical risers mounted inside the premises of a building or structure.

Schematic representation of the internal and external organized drainage system on a flat roof