Calculation of the number of funnels for a flat roof. Drainage device from pitched roofs: gable, hip and multi-level. Calculation of the load on the drainage system

The final stage of the roofing device is the installation drainage system. Among various systems you need to choose the one that suits your requirements - metal with electroplated or plastic. Gutter manufacturers offer a complete range of accessories. For information on how to make the installation itself, read the article.

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).

When complex design roof gutters and pipes are determined by largest size roof projections.

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, which means that 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:

Installation of brackets and gutters

Fastening the drainage system begins with marking the installation sites of the brackets using a marking thread.

The center of the gutter should be located under the line of the lower edge of the roof. The gap between the line (shown as a dotted line in the diagram) of the continuation of the roof and the top of the gutter holder must be at least 25 mm.

The funnel is installed above the storm water inlet. The funnel must be fixed on two brackets or at two points. The location of the funnel can be in the center or on the edge (laid in the project). A hole is cut in the gutter with a hacksaw to fit the size of the funnel.

The brackets are fixed on the gutter line (the slope of the gutter line towards the funnel is from 2 to 5%). The installation step of the brackets is from 0.5 to 0.75 m (for selection, use the manufacturer's "Gutter system installation instructions"). The end bracket is mounted at a distance of 25-30 cm from the plug at the end of the gutter. The distance from the corner element to the bracket is no more than 15 cm.

The gutters are inserted into the brackets, starting from the back, plugs are installed on the ends. The joints of the gutters are fixed with special locks or connecting elements. The ends of the gutters should be located 50-100 mm behind the side cut of the roof. If the roof span is more than 8 m, an expansion element is required between the gutters.

Types of fastening and material of brackets

1. Brackets are installed on rafter leg. Use metal brackets.
2. When using a frontal (front) board, plastic brackets are used.
3. The brackets are attached to the deck using metal extensions. Use plastic or metal brackets.

Possible errors and consequences

1. The increased spacing between the brackets leads to sagging of the gutters.
2. Mismatch of the edge of the roof with the middle of the gutter leads to overflow.
3. Increasing the gap between the gutter line and the edge of the roof - splashing and overflow.

Pro tip:

When cutting gutters and pipes, the use of angle grinders is not allowed, as the coating is damaged and burrs remain. Cutting is done with a hacksaw. It is recommended to clean the cut ends with a file.

Installation of the curly part and drain pipes

The laying of 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 curly part is assembled, into which the upper end of the pipe is inserted.
3. The system is attached to the wall using 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 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 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 air gap not less than 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 through 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.

I am Mikhail, the director of the company, I have been working exclusively with roofs for more than 15 years. Below I will tell you about the intricacies and secrets of materials for the roof. If you have any questions, I'll be happy to answer and help.
Mikhail, LLC "STM-Stroy"

Not a single house can do without drains: water spontaneously falling from overhangs can cause too much damage. In order to competently and efficiently arrange a spillway, a drainage system is calculated.

Calculation of the drainage system according to SNiP

In accordance with the Norms and Rules, the following characteristics should be taken into account in the calculation:

• total roof area;
• average annual rainfall;
• temperature minimum in winter time in this area.

Rainwater drainage must also be taken into account.

When calculating the drainage for the roof, it is determined:

• Number of gutters: total length eaves overhang divided by the length of one groove.

AT this example the total length of the overhang is 36.4 meters. Subtracting the length corner elements(20 cm on one side 12 * 20 cm = 2.4 m), 36.4-2.4 = 34 meters remain. The length of 1 gutter is 3 meters. So you will need to purchase 12 gutters (34/3 = 11.3 pcs.).

• Quantity couplings for gutters - by the number of future connections;

In the example in the photo, you will need to buy 16 couplings:

• Number of brackets for fastening the gutters: total length of the gutter divided by the step between the brackets (60 cm for plastic, 70 for metal);

• If the system is not closed (there are gutters with open ends) - the number of end caps. For example, on a gable gable roof there will be two strings of gutters and, accordingly, four plugs.

note

• Corner elements of the gutters - depends on the number of external and internal corners at home. When calculating the total length of the gutter, you need to take them into account too, in order to minimize the amount of waste;

• Calculation of drain funnels - by the number of pipes;

• Pipes: the number depends on the number of drains and the height of the house. Curved knees are selected depending on the width of the overhang;

• Clamps - one piece for each section connection. For example, if one three-meter pipe is used for one drain - two clamps, at the top and bottom.

The pipe outlet is located 30 centimeters from the ground (or 15, if there is a collector).

Related Articles

Calculation of drainage by roof area

The drainage system is one of the main protective measures that contributes to the extension of operation roofing materials, facade and foundation of the building. Correct and competent calculation of the roof drainage system is the key to a long and reliable operation the entire building as a whole. Knowing the basic principles of calculating the components of a 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 gutter systems in climatic zones with low risk of freezing water.

• 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.

Optimal number of funnels

Main purpose internal system Drainage is the removal of water from the roof at any air temperature outside and regardless of the amount of precipitation. Disposal of water is recommended to be carried out in the general or rain sewer. Calculation of the number of funnels internal drain lead according to the rule: 1 funnel per 0.75 m 2 of the roof and 1 cm 2 pipes for water drainage. The funnels of the internal system are located along the longitudinal axis of the roof. It is forbidden to equip funnels and risers in the thickness of the outer walls, due to their possible freezing in winter period time.

The calculation of the number of drain funnels is carried out taking into account the following requirements:

• if there are no obstacles for the linear expansion of the gutter up to 12 meters long, then one funnel will suffice;
• with a gutter length of more than 12 meters and there are obstacles to its expansion, then one special compensating funnel will be required at the end of the slope;
• if the gutter encircles the building along the perimeter, then the joint installation of funnels and compensators will be required.

The calculation of drain funnels must be performed on the basis of their passport data, which contains information about the geometric dimensions, method of attachment and bandwidth. The number of drain funnels must correspond to the number downpipes throughout the drainage system.

Features of the calculation of gutters and pipes

When arranging an external drainage system, the entire building should be carefully examined for the presence of architectural features, protruding parts and depressions. The drainage system should not spoil the appearance of the building, so if it does not fit harmoniously on the facade, it should be hidden from back side. For these purposes, numerous accessories are used, which are mass-produced today.

The calculation of the gutter system must always begin with a measurement of the roof area from which water will be removed. This can be done quite simply, knowing the simplest geometric formulas. Nominally, it can be assumed that a water drain pipe with a diameter of 100 mm is able to work effectively on a roof area of ​​up to 220 m 2.

The calculation of the cross section of the gutter is carried out taking into account the angle of the roof slope, the steeper it is, the higher the side height at the gutter should be. This is primarily due to the increase in the area of ​​collection of precipitation, which is the main source of water. The number of gutters is selected based on the perimeter of the cornice and the components offered on the market. So, most plastic gutters have a length of 3 or 4 meters, and galvanized - 2 meters. If the length of the cornice is 10 meters, then we will need 5 galvanized gutters or 2 pieces of 4 meters each and one of 3 meters in the case of plastic parts.

It is important to know that the number of connectors for gutters is always exactly one unit less than the gutters themselves.

The number of fastening hooks is counted according to the following formula:

N=(L - 0.3)÷(0.6 +1);

where N is the number of hooks;

The downpipe count can be found using the formula:

N \u003d (0.2 × H cornice - H bend + L insert) ÷ L pipes;

where N is the number of drainpipes;

H cornice - height from the ground to the cornice;

H bend - the height of the pipe bend;

L inserts - the length of the funnel insert;

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

It is important to know that at least two clamps should be used to secure each piece of downpipe.

To perform the calculation of the internal drain according to the pipe section, it is necessary to determine maximum amount water that can come from the roof. For this purpose, they measure geometric parameters roofs (length and width) and multiplied by the maximum amount of precipitation determined for the area. In most cases, a simplified formula is used, taking into account that there are about 1 m 2 of roof per 1 cm 2 of the downpipe section.

Calculation and determination of the optimal configuration of the drainage system.

The gutter must cope with the main task - to divert any amount of water from the roof. The calculation of the drainage system is performed in order to determine its optimal configuration and avoid disruptions in operation.

Proper selection of the diameters of pipes and gutters is the key to the performance of the entire system. Therefore, it is better to transfer such a responsible task, how to calculate the drain, to professionals. But in order to determine the cost of the system before purchase, there are special tables and formulas in the instructions for gutters. According to them, you can pre-calculate the drainage system.

Calculation sequence.

1. Collect initial data

The calculation of the drainage system is carried out according to the roof plan and facade drawings or on the basis of measurements.

1.1 Measure the height of the house.

To find out the required length of pipes, we measure the distance from the ground to the cornice overhang, indicated in Figure H. You can use a tape measure by lowering one end to the ground.

Fig 1

1.2 Measure the length of the eaves on each slope.

For measurements, use a long tape measure. The perimeter of the eaves is needed to calculate the total footage of the gutter. And the exact selection of the quantity is carried out for each slope separately.

1.3 To calculate the length of the pipes (riser), take measurements from the cornice overhang, measure the distance from the ground to the drain with a tape measure.

1.4 Determine the area of ​​the roof.

Before calculating the gutter, we calculate the effective roof area. The larger it is, the more rainwater will have to be diverted to the system, therefore, based on the area, the pipe section is selected. The roof area is calculated for each slope separately, and then summarized.

For example, if the slope rectangular shape, then:

S=B×L, where:

S - effective roof surface area, m2;
B is the actual width of the slope, m;
L is the length of the slope along the eaves, m.

Rice. 2.

The area of ​​​​the slopes, which have a complex shape, is calculated as the area of ​​\u200b\u200bthe corresponding geometric figure.

The generalized formula for calculating the number of pipes with a diameter of 100 m: 1 downpipe per 100 m2 of roof projection. But the total roof area can only be used for preliminary selection of the number of drain funnels. The calculation of the drainage system should be done for each slope.

Advice. The location of funnels and pipes also depends on the length of the eaves. For eaves up to 12 m long, the storm water inlet can be installed anywhere, over 12 m - closer to the center of the eaves. In this case, the distance between the funnels (storm water inlets) should not exceed 24 m.

Rice. 3.

How harder shape roofing and architectural features buildings, the more difficult it is to calculate the drainage system. The number of storm water inlets or risers depends on the shape and area of ​​​​the roof, as well as on the selected diameter, which will be discussed later.

2. Select gutters and pipes for PVC and metal gutters.

The dependence of the pipe section and the width of the gutters on the roof area is indicated in the tables attached to the instructions for installing gutters. For each manufacturer, these values ​​\u200b\u200bare slightly different according to the product sizes.

The most in demand in cottage construction are drainage systems designed for slopes with an area of ​​\u200b\u200bno more than 200 m2.

Tab. one. Calculation of the PVC gutter system PROFiL

Tab. 2. Calculation of the Plannja metal gutter system

You need to select a system based on the area of ​​\u200b\u200bthe roof and the throughput of the drain. Drainage systems presented in Ukraine, including, and, are designed for local rainfall. Adhering to the recommendations of manufacturers, you can determine the parameters of the drain.

3. Select the necessary elements of the drainage system

The composition of components for gutters different manufacturers may differ. In addition to the main elements of the system - pipes and gutters - you need to use additional components from the same manufacturer: connectors, plugs, fasteners. Tees, storm wells, garbage nets will ensure the proper operation of the drain and make its operation more convenient.

General form	Element	Basis for calculation	The need to use	counting form
	Storm water inlet (funnel)	roof area, drainage capacity	necessarily	tables 1, 2; section 4.3
		cornice length		section 4.1
		number of building corners	when going around corners with gutters
	Gutter holder (bracket)	distance between holders	necessarily	section 4.2
		number of gutters
		number of completed gutter systems
		gutter length		for each cornice
		building height		section 4.4 for each stand separately
	Pipe connector	number of pipes
		number of risers
	Inserting a pipe into the "swan neck"	eaves size	when carrying out the eaves more than 300 m
	Drain (drain elbow)	number of risers	necessarily
		number of combined risers	protrusions or union of pipes
		number of risers	in the presence of storm sewer
		number of risers

Tab. 3. Drainage elements, features of their application and calculation

Having decided on a set of gutter components for your home, we proceed to calculate the number of each of them.

4. How to calculate the drain - detailed instructions

4.1 Number of gutters and corners.

For the entire perimeter of the roof, the approximate number of gutters is calculated using the formula:

N_gutters=L+3.0 m,

where: L is the total perimeter of the eaves.

The most common standard gutter length is 3 m. After the gutter has been calculated, the number of gutters is specified by selection for each slope to minimize residuals. The corners of the gutters (external and internal) are calculated by the number of corners of the building.

4.2 Gutter connectors, plugs and brackets.

Gutter connectors for multi-piece splicing for each eaves are calculated separately according to the formula below, then summed up:

N_connectors=N_gutters-1

Advice. When working with PVC gutters, the connector is mounted so that at least 60 mm remains between the ends of the gutters to compensate for linear expansion.

Stubs are counted in fact. For one complete gutter system - 2 plugs.

The number of brackets for gutters depends on the step of their installation.

N_brackets=(L_gutter-0.3)/i+1,

where: L_gutter is the length of the gutter on the ledge for which the calculation is made.

i - bracket installation step, which depends on the gutter material.

0.3 - the sum of the distances from the extreme holder to the edge of the slope on both sides.

Rice. 5

Holder classification	Appearance	Characteristic	Mounting Features
By appointment		for PVC gutters	set at intervals of 50 cm
		for metal drain	set at intervals of 60 cm
Type		compact	attached to the front board
		universal	fastened to rafters or crate
According to the method of fastening		PVC and metal	the gutter is fixed with snaps
		metal	the gutter is fixed with folding "petals" and rivets

Tab. four. Features of mounting holders depending on the material and purpose

4.3 Number of funnels.

Answering the question of how to calculate the drain, we determined the number and location of the drain risers (pipes). The number of funnels is taken the same. You can check the accuracy of the calculation according to the tables (tab. 1, tab. 2), substituting your values ​​​​of the area of ​​\u200b\u200bthe slope and the number of risers.

4.4 Pipes, elbows, pipe connectors are calculated separately for each riser.

N_pipes \u003d (H-0.25-N_lsh + L_inserts) / L_tr,

where: H is the height from the eaves to the ground;

0.25 - distance from the ground to the drain;

N_lsh - the height of the "swan neck";

L_tr - the length of the drainpipe itself (3 or 4 m);

L_inserts - the length of the insert in the "swan neck", depends on the width of the cornice overhang (M) and the height of the "swan neck".

"Swan Neck"- an element for diverting the pipe from the eaves to the wall. It includes two knees at an angle of 45 ° , 60° or 70 ° from different manufacturers and inserting a pipe between them. Usually an insert is required where the width of the eaves overhang is more than 250mm.
When calculating the insert, you can focus on the tables:

Tab. 5. Insert size at knee 60 °

Tab. 6. Insert size at knee 70 °

As an option, use a simplified diagram by measuring the length of the insert between the two knees and add 100 mm.

Rice. 7.

When calculating the PROFiL gutter system (or other PVC gutter), connectors are used to connect pipes of a standard length of 4 m.

Connector calculation:

N_connection \u003d N_pipes - 1,

where: N_pipes - the number of pipes in one riser.

The number of elbows is determined on the basis of 2 pipe elbows and 1 drain (drain) elbow for each riser or drain funnel in the system.

For organized drainage at the end of the pipe, instead of a drain, they mount storm well. If the pipe bends around the protrusions on the facade or two pipes are connected by a tee, then this is taken into account in the calculation.

4.5 Pipe holders.

Systems made of metal and PVC have their own characteristics that must be taken into account when calculating. The more complex the architecture of the building, the more important the application auxiliary elements and their correct selection. Before you calculate the drain, determine the list and number of all necessary elements, including fixtures and accessories for the gutter. It is better to entrust the calculation of the drain to professionals, especially if the building has a complex roof. Then the system will maximally correspond to the features of the building, which guarantees its long and efficient work all year round. The house will be reliably protected from rain. And a well-thought-out calculation of the drainage system will improve appearance the whole house, because the optimal number of elements is used for correct operation drain.

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The internal drainage system is a whole complex of elements that perform a specific function. The whole structure works as follows: water flows into the gutters, through which it enters directly into the funnels. The correct calculation of the drain is impossible without data on the funnels, which are considered an important link in the entire structure.

The funnel of the internal drain is a structural component into which water that has fallen into upper part catchment. The element is located longitudinally to the roof axis at the lowest point of the roof, which is hermetically connected to the downpipe. The main purpose of the component is to remove water from the roof. Funnels are of two types: flat and in the form of a cap. The former are applied to flat surface, the latter - on roofs with a slope.

The funnel may not be represented in singular. According to SNiP, the number of components on a flat roof must be at least two. General requirement depends on the diameter of the downpipe: one ordinary pipe should have no more than 250 square meters. m. roof.

Factors affecting the amount

A correct calculator that makes an efficient calculation must meet the following requirements:

• If there are no obstacles between the downpipes to expand the gutter to 12 meters, then one funnel will be enough;
• If the distance from the blind area to the downpipe is more than 12 meters and has no obstacles, then two or more components are needed;
• If the gutter is not connected to the downpipes, but covers the building along the perimeter, then joint development of funnels and compensators is needed.

The main factor that the calculation procedure should take into account: the number of funnels directly depends on parameters such as the diameter of the drainpipe and the area of ​​\u200b\u200bthe roof. The latter depend on the height of the building and the number of places where water flows. General formula calculation can be represented as follows:

1 component = 0.75 sq. m flat roof and 1 sq. see pipes. Example: given a roof area of ​​100 sq. m and 125 sq. see pipes. Based on the ratio, we get approximately 130 funnels for a hundred-meter roof area.

Knowing the diameter of the drain pipes and the coverage area, you can calculate the number of components that will later help in calculating the drain for the roof, because the funnel is one of the main components of the entire structure.

Calculation of the entire structure

To calculate the drainage system, you need to know the following characteristics:

• roof area;
• Temperature minimum in winter;
• Average annual rainfall.

These parameters must be known in order to calculate the drainage system. The entire structure of the drain consists of brackets, funnels and gutters. Therefore, the formula that calculates the drainage system of the roof must include information about the component parts of the system. In terms of funnels, the dependency looks like this:

• If the diameter is 80 mm, then the water flow is approximately 5 l / s .;
• If the diameter of the funnel is 100 mm, then water is consumed at a rate of 12 l/s;
• With a diameter of 150 mm, the water flow is considered to be 35 l / s.

Knowing how to calculate the number of funnels, you can calculate the approximate amount of water consumption of the entire structure. For outdoor drainage, which loses popularity over time, different rules apply, and therefore the calculated result will be different. A calculator that calculates the internal drain and takes into account such a component as a funnel helps to obtain complete information about the entire structure.