Drainage of a flat roof specifics of the construction of internal and external options

The main types of drainage system

The internal drain of its elements and device is a variety of nodes, gratings and sockets. Now companies can manufacture such systems to order, according to all the provided parameters and sizes that the customer will need. You just need to develop a project and coordinate it with the engineers. Typical internal gutters are made of alloy steel, aluminium, PVC. Of course, you can use plastic pipes, but they are not designed for a large flow of water, and will immediately begin to be damaged. But internal gutters made of steel pipes are much more stable and reliable, they can withstand any flow of water, and will last a fairly long time.

But they can make a lot of noise, because water gets in, swept and makes loud sounds.

Copper drains are considered one of the best drains, but they are quite expensive, but they are unmatched in durability, they can even withstand acid rain that occurs in industrial areas. Previously, cast iron drains were also often used, but they did not justify themselves, because they are quite difficult to install due to their large weight. Pipes for internal drainage of water can be with different sections. But mainly a rectangular profile is used, because it is very easy to operate and does not require special care.

Organized pitched roof drain what is it and why is it needed

To date, there are several types of drainage:

• Disorganized.
• Organized internal.
• Organized outdoor.

An outdoor organized drain is considered the most popular, so let's start the story with him. It is a whole system consisting of various gutters, drain pipes, fasteners and other parts that attach the structure to the roof and walls of the building.

IMPORTANT!

The principle of operation of such a structure is quite simple, consisting in collecting water from the surface of the roof, after which it circulates through the gutters, falling into the downpipes. Then the water moves through the pipes, after which it flows directly into the sewer.

This type of drainage has undoubted advantages over other types of drainage:

• The organized drainage system is fully thought out, so all water is outside the premises, i.e. outside the building itself. This suggests that moisture cannot exert its negative effect on the structure itself, which can significantly extend its service life.
• The system is designed in such a way that all fasteners are within easy reach, which greatly simplifies various repairs in case of breakdowns.
• An organized drain can be done on your own, without the involvement of third-party labor.
• An organized drain performs not only its direct function - it removes water from the roof, but also decorates the facade of the building. On sale there are modern materials from which the drain is made, so it is quite possible to choose the option of interest.

Elements of the drainage system

An organized outdoor drain is very well suited for a pitched roof.

For the arrangement of this system, the following materials are most often used:

• The metal is galvanized. This material was the most popular several decades ago, but now it is gradually losing ground to more modern materials. The average life of a gutter made of galvanized steel is 12 years.
• PVC or plastic. Such material is now most popular in the construction of gutters, due to its low weight, as well as the relative ease of installation. The average service life can reach 30-35 years.
• Copper drain.Such a material outperforms all those named according to a variety of criteria, but there is one significant drawback - this is the high cost of copper itself.
• Metal-plastic. Such material is considered relatively young, therefore, it is not as widespread as the previous ones. However, it combines the advantages of PVC material and galvanized metal, and its service life can reach 50 years.

Gutter system

Installation rules

Some rules for installing an internal drain can significantly increase the efficiency of the system as a whole, by improving its functioning. The basic rules and requirements for the installation of an internal drain are contained in SNiP -85.

Drains and gutters below them must be located in the lower parts of the roof, as well as evenly distributed over the entire area of ​​the roof. This will help to better collect precipitation.

The slope at a distance of more than 50 cm from the water collection funnel is made by an amount not less than 5 percent. This can be done by special leveling screeds or by using a heat-insulating layer.
In order for the bowl of the drain funnel not to rest directly against the heat-insulating material, it must be placed on a special wooden beam, pre-treated with an antiseptic. It must be installed on the base of the roof

And to it is already attached directly to the water intake.
The junction of horizontal and vertical drain pipes must be made using a special adapter that ensures direct water ingress.

It is very important, when the funnel is above the freezing point, to heat it with special electrical appliances. Thus, it is possible to prevent the shutdown of the system at sub-zero temperatures.

If the distance to the warm rooms of the house is more than one meter, experts also recommend heating the horizontal pipes of the drainage system.

It is important to install heating elements due to the fact that in the case when they are absent, ideal conditions are created for the occurrence of roof leaks. And this, in turn, affects many parts of the house, including their internal state.

System installation

Strengths of a flat roof

If you live in a big city, you are probably familiar with flat roofs. They can be found in almost every high-rise building. High-rise buildings, as a rule, are equipped with an internal drain so that water falling from above cannot harm the surrounding buildings. Until recently, such roofs could only be found on industrial and multi-storey buildings, but with the advent of new roofing products, they began to be built in private construction.

What is it that attracts developers so much? Most likely, people are simply tired of the image of a standard pitched system. Of course, there is no doubt about its practicality, but such roofs are found in private buildings absolutely everywhere. Therefore, if you want to stand out from the rest, then you still have a chance to do it.

Residents of Western countries have long used buildings with flat roofs and describe them exclusively from the positive side. And this is not surprising, because for a small price you get additional living space, which you can use at your discretion, the main thing is to create all the conditions for this. A flat surface is reliably protected by modern roofing materials, so you won’t have to think about repairs.

So, let's look at the positive qualities of a flat surface:

• Compared to pitched roofs, flat roofs have a smaller area, so the device will require much less materials. From an economic point of view, this is very beneficial.
• You can also save a certain amount by refusing the services of a roofing team, doing all the work yourself.True, it will be a bit tight without a partner, so invite one of your friends.
• It is much more convenient to carry out installation work on a flat surface than in a suspended state, so it will proceed not only easily, but also quickly.
• By servicing the roof at any time of the year, you can be sure that you will not harm your health in any way.
• The additional area created as a result of installation can be used at your discretion. It can accommodate a recreation area, place a playground, a workshop, grow a garden and much more.

Often, as I list these flat roof properties, many builders are tempted to start building right now, but it's not as easy as it sounds. The whole difficulty lies in the design of such a roof, and if any element is not installed correctly, then soon such a surface will fail.

The drainage system of a flat roof is one of its most important components. As you already know, it can be equipped with both internal and external methods. If we consider the first, then it is a device of a complex system of pipes inside the building, which in a certain way divert precipitation from the surface into the storm sewer. Such a system allows you to improve the appearance of your comfort and make it more attractive and mysterious. As for the second method, these are the usual pipes that are visible from the outside of the building. As a general rule, outdoor drainage from a flat roof is arranged only if your finances are limited or if your area has severe winters.

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Recommendations for the operation of flat roof gutters

During the operation of buildings and structures equipped with a flat roof, in order to prevent flooding of internal premises, it is necessary to take a number of measures to prevent such phenomena.

Here is what to do for this:

• clean the water intake funnels from foliage and other foreign objects;
• check the tightness of the joints of structural elements and, in case of depressurization, restore it (change sealing gum and cuffs, use sealant);
• if financially possible, create an electric heating system (heating cable) that ensures the absence of snow and ice in places where water flows (funnel, gutters, etc.).

The implementation of these measures will help to avoid negative phenomena caused by the penetration of water to building structures and on the ground near the facade of the building.

The use of a heating cable will avoid ice plugs in the roof drainage system.

Positive and negative points of the internal drainage system

If you are planning to create an internal downpipe system, then you should know that it comes in two types:

1. Gravity. Here, precipitation is removed by gravity and it all looks something like this. When enough moisture is collected on the roof surface, it begins to move towards the collection funnel. Once in it, it flows down the pipe and out of the building.
2. Siphon-vacuum. The operation of such a system is much more complicated. Rain or melt water enters the collection funnel and moves through a horizontal pipe connected to a vertical riser.

The systems described above have their own strengths and weaknesses. First, let's take a look at gravity.

The gravity drain has a rather low throughput, so it may happen that during a heavy rain it simply cannot cope with the incoming volumes and a pool appears on the roof, which can cause the destruction of the entire structure.

When creating such a system, it is very important to study the average annual precipitation in your region.If these are large values, then do not hesitate and install the maximum possible pipes and funnels to collect water

The siphon-vacuum drain copes with the above problem very simply. The fact is that all precipitation enters the drainage system under vacuum. And as soon as the vertical elements are filled to the top, the process of the second discharge begins, and the pressurized liquid is discharged into the collector, and subsequently, into the storm drain. Thanks to this process, this drain has a high throughput.

The advantages of the siphon-gravity system include the following points:

• Water collection can be carried out not only from flat surfaces, but also from any other.
• Smaller diameter pipes handle large volumes of water without problems.
• Due to the large bandwidth, there is no need to arrange a large number of channels.
• Due to the rapid withdrawal of water from the system, its possibility of clogging is significantly reduced.

If we compare the internal and external drainage, then the advantages of the first are obvious:

• You will not see any protruding elements along the perimeter of the building.
• Work to remove moisture can be carried out at any time of the year.
• The moisture flowing down the pipes is immediately sent to the storm sewer.

The disadvantages of internal flow include the complexity of its creation, maintenance and cleaning.

As a conclusion, I would like to say a few words about the flat roof in general. Every year this design is gaining more and more popularity among private developers. Thanks to this growth, manufacturers of building materials are thinking about the production of new materials, which is moving this area forward.

Having created a flat roof, you can equip it to your taste. You can grow a garden on it, open your own workshop or equip a recreation area. By the way, if you make more complex calculations and invest a little more money in construction, then you can even place a swimming pool or a car park on the roof. However, nothing keeps you from implementing a unique idea.

Pro Tips

If you are installing an internal drain for the first time, pay attention to your experts

1. Installation starts from the bottom, gradually you need to go up.
2. All channels and shafts inside the building intended for water supply, after its installation, must be closed with panels. This will keep the temperature constant.
3. When choosing a drain funnel, please note that it must fit the roofing material of the roof.
4. The places where the funnels are installed should be slightly lower than the rest of the surface. a slight slope can be done on purpose.
5. Metal pipes in the internal system must be equipped with electric heating, otherwise they will freeze in the winter and may burst.

The device of the internal drainage system is more complicated than the external one.

It is important to pay attention to the accuracy of calculations, and during installation - to the tightness of the connections.

Rules and nuances of the installation process

It should be noted that the internal gutter will work for a long time and efficiently, if it is done correctly. You can correctly calculate, use the best and highest quality materials for its construction, but even the smallest mistake during assembly or installation will lead to big problems. Therefore, it is worth being very demanding in observing fairly simple rules.

• If flat small house roof, then you can install two water funnels. If area big, then it is necessary to calculate the required number of water intake elements and evenly distribute them over the entire plane of the roof. The Code of Practice states that one funnel should be established to the square in 20 m².

• It is forbidden mount funnels closerthan 1 m from the walls of the building.

• Distance between neighboring funnelsconnected to one pipe riser should not be less than 20 m.

• If one was chosen as the material for the elements of the drainage system from metals, then it is necessary to equip the entire drain heating cable. This is a necessary measure that will protect the entire system from deformation and rapid failure.

How to properly install internal gutters

If the flat roof of the house is multi-level, then each level has its own drainage system with an accurate calculation of the elements, both in quantity and in parameters.

Particular attention to those multi-level roofs, in which the difference in planes is more than 4 m. And once again about the tightness of the joints

Special attention is paid to this parameter, because the repair of the internal drainage system is much more difficult than the external one.

Usually the entire surface of the roofing plane is divided into sections. At the same time, 150-200 m² is allocated for each riser.

The slope of the roof towards the water intake funnel should be 1-2 °.

The calculation of the pipe section is carried out taking into account the following ratio: a riser with a cross section of 1-1.5 cm² should be installed on 1 m² of the roof plane. This is the simplest form of calculation, but it usually works.

All risers must be installed in the heated areas of the building, otherwise it is likely that in winter they will simply freeze.

The funnel is installed so as to fully ensure its tight fit to the plane of the roof structure. Therefore, the rolled material is usually laid over the sides of the funnel.

To reduce the noise of moving water, it is recommended to cover the pipe elements with noise-absorbing materials.

How to properly install a water inlet funnel

As practice shows, it is the installation of funnels that causes some difficulties. The main thing here is to achieve complete tightness of the clamp. Therefore, a glass is inserted into the hole that is made on a flat roof to install a water intake device. It is he who will form the water intake and provide sealing.

The glass itself is installed only when the lining carpet is laid on the roof. That is, a waterproofing material that is always laid under the roofing, even rolled. The sides of the glass should lie on top of the waterproofing, which will already ensure the tightness of the structure. The funnel is fastened with adhesives or self-tapping screws.

After that, roofing material is laid on the roof. As for the formation of the hole, it is usually done like this:

• lay the strip roofing material over glasses;

• then cut with a sharp knife hole exactly edges of the device;

• then install cap or protective lattice.

The video shows how to properly install an internal drain funnel on a flat roof:

We add that funnels, consisting of two parts, justify themselves one hundred percent. They easily compensate for the movement of the insulation with changes in air temperature.

There is one more point that concerns the efficient operation of the internal drain. This is the connection of funnels to one riser. Usually, outlet pipe sections are used for this, which are laid under the ceiling of the building, but above the ceiling. Since the drain is a gravity system, these sections must be laid at a slight slope - 1-2 °. It is they who must be insulated with noise-absorbing materials.

And the last

Equally important is the heating system of the internal drain. The most important thing is to prevent pieces of ice from getting inside the system, which will block the section, which will lead to clogging.

Therefore, it is near the water intake funnels that the heating cable is laid. There are many different location options, one of them is in the photo below.

How to lay the heating cable near the water intake funnel

Features of the internal drain

When mounting an internal drainage system, you must conditionally divide the entire plane into sectors. This is done because one drain can serve a surface of no more than 200 square meters, it simply cannot cope with a large volume and water will accumulate on the surface. Although a flat roof has such a name, its surface is arranged under a certain degree. This process is called creating a ramp. It can be created using a screed or heat-insulating materials.

Of course, the simplest and fastest option is a screed. To create the desired slope, concrete mortar is poured over the floor slabs, and when it hardens, subsequent layers of waterproofing are laid. Next, heat-insulating material is placed. It must be rigid, so of all possible products, it is best to use expanded polystyrene or foam glass. These two materials are not afraid to get wet and a thickness of 15 centimeters is enough for thermal insulation.

The final coating will be selected based on the functional purpose of the surface. If it is operated, then the following can be used as a protective layer: soil, bulk materials, paving slabs, etc. In the case where the surface is not capable of withstanding heavy loads, it is necessary to consider products with a lower mass, for example, bituminous, polymeric or sprayed materials.

The internal drainage system, although complex, includes simple devices, namely:

• Funnel and gutter to collect water from the roof surface and transfer it to the drain line;
• Risers, which are the main path for rainfall;
• A collector arranged in the ground with a system of pipes that drain water into a storm sewer.

To quickly remove precipitation from the roofing plane, it is necessary to use pipes with a diameter of 100-180 millimeters. The required pipe section can be determined based on the consideration of 1.5 square centimeters of the pipe section per 1 square meter of the roof surface. The length of one element should be in the range from 700 to 1400 centimeters.

When designing the placement of the drainage system, you should find an element from which heat will emanate all year round. As a rule, it is a chimney. By installing a drain near it, you will allow the internal system to remove precipitation even in the winter season.

IMPORTANT: If you live in a region with severe winters, then for the reliability of the drainage system, partial or complete heating of the roof is arranged

Varieties

A characteristic difference between the internal drain and the external one is the installation site, since the installation is carried out inside the structure. On the one hand, this design provides some advantages, on the other hand, it is associated with difficulties, since each node must be securely sealed to prevent leakage. The number and diameter of the elements determines the calculation based on the determination of the roof area and the amount of precipitation. There are two types of internal drainage system:

• Gravity. A gravity-flowing type of drain is the simplest option, the calculation and installation of which is carried out without much difficulty. The design includes the following elements: funnels, outlet pipes, risers. The gravity system is inefficient, it will not cope with the influx of water that the roof is exposed to during heavy rains if the diameter or number of elements does not match the parameters that the calculation showed. The advantage of this solution is the low price.

  Differences between gravity and siphon drainage systems

• Siphon. A drain operating on the principle of a siphon differs from a gravity drain in greater productivity.The siphon drainage system is completely filled with precipitation, due to which a water column is formed in it from the water intake funnel to the outlet to the sewer. If the liquid level in the riser drops, then a rarefaction zone is created in the funnel, sucking moisture from the roof surface. The price of installing a drain of this type is higher due to the cost of special funnels with flow stabilizers. For the work to be effective, you should perform the calculation, as well as select high-quality material. The advantage of this design is that with the rapid movement of water, each gutter unit is self-cleaning, regardless of what material was used.

Inlet funnel with flow stabilizer for siphon drain

Types of gutters for roofs

In order to choose the right type of funnel for a flat roof, it is necessary to start directly from the roof structure. This means that terraces require different types of drainage systems than green roofs. In the first case, the device is flat, which makes it possible to walk on it without obstacles.

In the second case, the funnels must be fenced with a special mesh that can trap various contaminants - leaves, grass or dirt. In addition, in this way, small animals also cannot get into the drain. This also applies to domestic cats.

Gutters of the internal location can have various designs in their appearance. Specialists distinguish siphon and gravity (gravitational) types. The first type collects climatic precipitation from the entire roof with the help of special water inlets. The system allows water to drain freely by tilting.

Gravity and siphon system

Siphon types of drains suggest stagnant water in the entire system. This applies to both the funnel and the entrance to the sewer. The liquid is sucked in due to the pressure occurring in the siphon. Thus, it is pumped into the sewer risers. Such a system works due to the fact that irritation energy is generated, which occurs due to a drop in the water level in a vertical column.

Pipes should also be selected in a special way. They must be of high quality treated with sealant. This prevents water from leaking out of the system. The siphon itself must be provided with a special additional device - a water flow stabilizer.

Siphon system

The internal drain in a multi-storey building is most often equipped with a heating system and special protective nets.