As the current SNiP prescribes, the internal drain as a sanitary system is calculated by the architectural and construction part of the project in each case.
The drain carries a huge functional load, although at first glance it does not seem to be such an obligatory phenomenon in a residential building, but a lot depends on its absence or presence.
To answer why internal drains of buildings are needed, it is necessary to recognize them as part of the roof system, which serves to protect the building from atmospheric precipitation.
The drain is assigned the role of a "vehicle", which needs to be removed from the roof, walls and foundation of the house as quickly and as far as possible from the moist environment - melt and rain water.
Errors in the form of omissions or superficial consideration of the drain when designing a house threaten further problems with redevelopment, complicating construction and finishing work in the first place, both in the building itself and in the arrangement of the adjacent territory.
That is why at the stage of planning the construction of a residential building, the internal drainage system must be worked out together with gas supply, water supply and sanitation.
Functional purpose of the drain
Let's figure out what is an internal and external drain, what is their role and fundamental difference from each other in a residential building.
To do this, you need to start with the main purpose of the drain as an engineering structure, which is to drain rain and melt water from the roof of a residential building.
But since we live in a climatic zone, which is characterized by a seasonal change in weather conditions, the requirements for trouble-free operation all year round are imposed on the drain.
So, with sharp changes in external temperatures, the internal drainage system is the most convenient and practical.
Advice! If a traditional shed or gable roof is being designed, then it will be cheaper to design an electrical heating system for the external drain.If the roof is flat (operated), then it is preferable to arrange an internal drainage system.
It should also be noted that internal drainage systems are more suitable for flat roofs, since the funnel of the internal drainage is also located inside the building structure.
If the roof has a different shape (single-pitched, gable, broken, gable or tent), then for the arrangement of a drain with an internal location, it should be designed differently, or an external drainage system should be provided.
A distinctive feature of the drain inside the building
The internal drainage device in a building is a water drainage system, reliably protected from climatic and temperature changes, which is located not outside, but inside the building structure.
Advice! The best options for arranging such roof drainage system - this is its installation in a single riser of the bathroom, parallel to the sewer pipe, or ventilation system, which will further increase heat transfer, and wastewater in such a system will not be subject to freezing.
A significant difference between the two roof gutters also lies in the materials for manufacturing. The outdoor system must be additionally protected from the effects of precipitation. As a rule, this is a galvanized metal that resists corrosion, and the cost of which is quite high.
In addition, the external roof drainage system is susceptible to damage if the drain freezes in winter, and is also subject to mechanical stress due to its openness - dents, penetration due to careless handling.
The internal drainage system is free from the problem of freezing and physical damage, and is also less demanding on materials. Pipes made of plastic, metal, asbestos, PVC and cast iron are suitable for its arrangement.
The design of the internal drainage system from the roof
Structurally, the melt and rain water drainage system consists of three parts:
- Upper part (catchment);
- Internal part (riser);
- Lower part (outlet).
The upper part of the system is nothing more than a funnel with a protective cover in the form of a grid or crate, which prevents large debris (branches, leaves) from getting inside.
The funnels of the internal drain are installed at the lowest point of the roof surface, and are connected to the drainpipe, forming an airtight connection.
Inner part drainage from the roof is a vertically installed drain pipe, colloquially referred to as a "riser", passing inside the building, and serving to pass water from the roof of the building.
The lower part, called the outlet, serves to remove water from the drainage system either into the storm sewer or outside the house.
Calculations for arranging a funnel
According to current regulations, the number of drainage funnels on the roof is calculated based on the standard that one downpipe should not exceed 250 sq.m. roof surface.
However, much depends on the design features of both the roof itself and the intensity of precipitation for a given area. Based on this, the throughput of the drain, the diameter of the drainpipes and the volume of the storm sewer are calculated, if such is provided for by the project.
Example: The average precipitation rate for this area is 75 mm per hour. If the funnel is designed for a flow rate of 6.45 l / s, then it can effectively collect water from a flat roof with an area of \u200b\u200bup to 300 m2, respectively, it needs an inner pipe with a diameter of 82 mm.
If the efficiency of the funnel is greater (10.72 l / s), then it will require pipes for an internal drain with a diameter of 160 mm, and the entire system is able to serve up to 510 m 2 of the roof.
Installing a gutter inside a building
The first thing to remember is that any engineering system must be able to be serviced. This means that the laying of downpipes should be carried out in communication shafts or channels that provide free access for maintenance.
The prescribed height of the revisions on the risers is 1 meter from the floor surface.
Installation of a drain inside the building is carried out according to the following scheme:
- Primary marking of places for installing fixtures for drainpipes (riser);
- Calculation of the exit point of the riser to the roof slab;
- Determination of the exit point of the catchment funnel;
- Drilling holes for mounting;
- Installation of fasteners provided by the pipe manufacturer (PVC, cast iron, asbestos - all have different fasteners);
- Installation of an outlet pipe (connection to a storm sewer or outlet outside the house);
- Sealing the outlet with insulating plastic materials that are resistant to temperature changes;
- Installation and fixing of downpipes vertically;
- Installation of revision on pipes;
- Sealing all connections;
- Installation of the connecting part of the catchment funnel;
- Joint sealing;
- Seal roofing material funnel slopes;
- Installation of a clamping flange and a protective grid of a catchment funnel;
- Testing the operation of the water drainage system.
Installation should start from the bottom (basement, first floor), moving up to the last floor or attic in contact with a flat roof. During installation, temperature compensation of pipe materials should be taken into account, leaving gaps.
Tip: The best temperature compensated sealing solution is rubber seals.
After finishing work inside the building, it is necessary to close the communication shafts or channels with decorative panels, which will help maintain the temperature regime in the system.
The most difficult stage of the installation of the gutter is the work on the roof. Modern funnels are designed to work with any roofing material, which allows you to most effectively ensure the tightness of the connection.
It is only important to choose the type of funnel that is suitable for a particular roofing material.
Depending on this, different methods of fastening the funnel are used - from gluing, to clamping methods using stainless screws. In any case, at the end of the work, it is imperative to test the effectiveness of its work.
If we are talking about a multi-storey residential building, then the test results should be reflected in a document such as the Testing Act for internal sewage and drain systems.
This document will be required when obtaining permits for the operation of a residential building by the selection committee.
The gutter itself is an important system for protecting a building from excessive moisture, which cannot be neglected. Therefore, we recall once again that the design of an internal drain - SNiP, as well as common sense, is prescribed long before the start of construction work.
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