How to calculate the angle of inclination of the roof

Build any roof is not as simple as it seems. And if you want it to be reliable, durable and not afraid of various loads, then pre-at once at the design stage, you need to make a lot of calculations. And they will include not only the number of materials used for installation, but also determining the angles of inclination, rope area, etc. How to calculate the angle of inclination of the roof correctly? It is from this value that the remaining parameters of this design will depend largely.

Design and construction of any roof - always very important and responsible. Especially if we are talking about the roof of a residential building or complicated on the shape of a roof. But even the usual single-sided, installed on an unpleasant shed or garage, the same needs preliminary calculations.

If it is not possible to determine the angle of inclination in advance, not to find out which optimal height should have a hat, then the risk of constructing such a roof, which will collapse after the first snowfall, or all the finishing coating from it will be reduced even with moderate wind.

Also, the angle of inclination of the roof will significantly affect the height of the skate, on the area and dimensions of the skates. Depending on this, it will be possible to more accurately calculate the number of materials required to create a rafter system and finishing materials.

Units

Remembering the geometry, which everyone studied at school, can with confidence to declare that the angle of inclination of the roof is measured in degrees. However, in the books dedicated to construction, as well as in various drawings, you can meet another option - the angle is specified as a percentage (here is due to the aspect ratio).

Generally, the angle of inclination of the skate is an angle that is formed by two intersecting planes. - overlapping and directly with the roof. It can only be sharp, that is, lying in the range of 0-90 degrees.

On a note! Very steep slides, the angle of inclination of which is more than 50 degrees, are extremely rare in its pure form. Usually they are used only with decorative design of the roofs, may be present in the attic.

As for the measurement of the corners of the roof in degrees, then everything is simple - everyone who studied in school geometry has this knowledge. It is enough to draw a roof circuit on paper and using the transporter to determine the angle.

As for interest, then it is necessary to know the height of the skate and width of the building. The first indicator is divided into the second, and the obtained value is multiplied by 100%. Thus, one can calculate the percentage ratio.

On a note! With percentage ratio of 1, the usual degree inclination is 2.22%. That is, the skate with an angle of 45 ordinary degrees is 100%. A 1 percent is 27 angular minutes.

Table of values \u200b\u200b- degrees, minutes, interest

What factors affect the angle of inclination?

At the angle of inclination, any roof is influenced by a very large number of factors, starting from the wishes of the future owner of the house and ending with the region where the house will be located. When calculating, it is important to take into account all the subtleties, even those that at first glance seem insignificant. At one point, they can play their role. To determine the appropriate angle of inclination of the roof should be known:

types of materials from which the roofing pie will be built, ranging from the rafter system and ending with the outer finish;
climate conditions in this area (wind load, the predominant direction of winds, the amount of precipitation, etc.);
the form of the future structure, its height, design;
purpose of the structure, options for using an attic room.

In those regions where strong wind load is noted, it is recommended to build a roof with one row and a small angle of inclination. Then, with a strong wind, the roof had more chances to resist and not be torn. If the region is characterized by a large amount of rainfall (snow or rain), then the slope is better to do sharp - this will allow the sediments to roll / drain from the roof and not to create additional loads. The optimal slope of a single-table roof in windy regions varies within 9-20 degrees, and where many precipitation falls - up to 60 degrees. The angle of 45 degrees will allow not to take into account the snow load in general, but the wind pressure in this case will be 5 times more on the roof than on the roof with a slope of only 11 degrees.

On a note! The greater the roof slope parameters, the greater the amount of materials will be required to create it. The cost increases at least 20%.

Corners of rods and roofing materials

Not only climatic conditions will have a significant impact on the shape and angle of the skates. An important role is played by materials used for construction, in particular - roof covering.

Table. Optimal angles of slopes for roofs from various materials.

On a note! The smaller the inclination of the roof, the smaller step is used when creating a crate.

The height of the skate also depends on the corner of the skate

When calculating any roof behind the landmark, a rectangular triangle is always taken, where kartets are the height of the skate at the top point, that is, in the skate or the transition of the lower part of the entire system has rafted into the upper (in the case of mansard roofs), as well as the projection of the length of a specific slide on Horizontal, which is represented by overlaps. There is only one constant value here is the length of the roof between the two walls, that is, the length of the span. The height of the skate part will vary depending on the angle of inclination.

Designing the root will help knowledge of formulas from trigonometry: TGA \u003d H / L, SINA \u003d H / S, H \u003d LXTGA, S \u003d H / SINA, where A is the angle of the skate, H is the height of the roof to the skate region, L - ½ of the total length The span of the roof (with a double roof) or the entire length (in the case of a single roof), S is the length of the row itself. For example, if the exact value of the height of the skunk part is known, the angle of inclination is determined by the first formula. It will be possible to find an angle on the Tangent table. If the basis of the calculations is the roof angle, then it is possible to find the height parameter of the skate in the third formula. The length of the rafter, having an angle value of the inclination and parameters of cathets, can be calculated in the fourth formula.

Calculator calculating the height of the skate

Specify the requested values \u200b\u200band click "Calculate the height of the skate h"

Calculate for:

Building width D, (meters)

Planned angle of the roof of the roof α, (degrees)

How dependes the dimensions of the attic from the angle of inclination?

To make it possible to use the attic room, it is worth thinking about the construction of the attic. And here the angle of inclination of the roof acquires the so-called applied value. Depending on how this value will be, the free space of the attic room depends. So, the smaller the value of the angle of inclination, the less free space in this part of the house.

Important! The height of the ceiling in the attic can not be less than 2 m.

Thus, the attic must be built only with steep slopes. But in this case, certain problems are identified: the sizes of the roof increase, the height of the rafter design - also, the need to design the mass of the desired small elements will appear. Such a roof will be stronger than the "couple" and should be very strong to withstand various exposure to external factors.

Snow load values

Russia is a huge country, and the climate in different points can differ significantly from each other. Snow load indicators - too. There are 8 main zones separated by the intensity of the snow load.

To calculate the snow load on the designed structure, the formula of the RSN \u003d PST is used, where RST.N. - An indicator defined by special tables, and m is a correction ratio, which depends on the corner of the roofing corner. It will be equal to 1 if the angle of the skate varies in the range of 0-25 degrees, 0.7 - with rods 25-60 degrees. If the angle exceeds 60 degrees, the snow load during the design of the roof is not taken into account.

Values \u200b\u200bof wind load

Since the wind can change the direction of movement, reveal the wind load will be much more complicated than the snow. The roof thanks to him can be pressed to the base, but it can also be subject to a certain force that will strive to break it from home. Also, the wind acts on the whole structure unevenly.

To carry out the desired calculations, it will be necessary to use only the prevailing direction of the wind in the region, which is determined by the "Rose of Winds". Also, when calculating, it is required to take into account the presence of near buildings, mountains, forests and other elements that can not only change the direction of the wind, but also to some extent to regulate its strength, protecting the structure from shkvalov.

According to the map, you can identify the main wind characteristics prevailing in a certain zone of the country. Next is determined by the wind pressure of the RWT (kg / m 2). It will change depending on the zone:

Ia - 24;
I - 32;
II - 42;
III - 53;
IV - 67;
V - 84;
VI - 100;
VII - 120.

Then the formula is used RV \u003d RVT x to x withwhere K is the value of the coefficient depending on the height of the structure and the characteristics of the area, and C is the coefficient depending on the angle of tilt the slope and the direction of the wind.

Table. Definition of the coefficient K.

Build height, m	BUT	B.	IN
Less than 5.	0,75	0,5	0,4
5-10	1	0,65	0,4
10-20	1,25	0,85	0,55
20-40	1,5	1,1	0,8

A, B, B - these are certain types of zones, and - open naked terrain, where the wind load will be maximum, the zone B refers to small residential villages with the height of obstacles to 10 m, crossed areas or surrounded by forests of the territory, and B is a zone dense Buildings in cities where buildings height is 25 or more meters.

On a note! To determine which zone to choose in each case, the value of the height of the N building will help, which is multiplied by 30. Thus, a suitable zone radius is obtained. For example, at the height of the structure of 60 m, it costs to a circle with a radius of 2 km.

According to the above figure, great importance in determining the impact of wind on a certain section of the roof has an indicator E. It will be equal to 2khn or b (the one is chosen that less). The coefficient C is determined by the table, taking into account the angle of inclination of roofing rods.

Table. Value C (FRONTON).

Corner skate	G.	F.	I.	H.
0	-1,3	-1,8	-0,5	-0,7
15	-1,3	-1,3	-0,5	-0,6
30	-1,4	-1,1	-0,5	-0,8
45	-1,4	-1,1	-0,5	-0,9
60	-1,2	-1,1	-0,5	-0,8

Table. Value with (skate).

The total force effect on each section of the roof is calculated by the formula: RSUM \u003d RSN + RV. This indicator will be the initial rafters for calculating.

On a note! The easiest way to make calculations of the corner of the skate is not independently, but using online calculators or computer programs.

Option for calculating the parameters of the roof using the calculator

Step 1. The first thing in the browser offers a website where there is an online calculator. In this case, you can specify the mass of the parameters of the future roof. First, the roof shape is selected - for example, a single one.

Step 3. The lengths of the length and width of the roof base are selected, focusing on the image at the bottom of the page - there are shown to determine the designations used.

Step 4. You can immediately specify other values \u200b\u200b- the parameters of the rafter system, up to the instructions of the materials used for its structure. The value of the shade of the crate, the calculation of the snow load is also selected.

Step 5. Snow load is determined by the region where the structure will be. There is a convenient map-diagram for this.

Step 6. So that the calculations were made, the "Calculate" button is pressed.

Step 7. As a result, a detailed table appears on the page, indicating the main parameters of the roof, including the angle of its inclination.

We also give an exemplary calculation of the roof angle depending on the known value of the height of the skate. For the work of the calculations, the width of the front should be measured (for example, this indicator will be 6 m). Next, this value is divided into 2 - it turns out 3 m. The height of the skate in this case should be 1.8 m.

Now you just need to take advantage of the formulas known from the lessons of geometry and learn the Tangent Angle: tGA \u003d A: B \u003d 3: 1.8 \u003d 1.67. The value of the tangent value can be found in the Bradys table. In this case, the angle of the skate will be equal to 58-59 degrees. It can be rounded up to 60.

Video - Finding the inclination and height of the roof

The calculation of the roofing rod is a rather complicated procedure for those who are not friendly with mathematics. However, if desired, it can be understood with all these formulas and all calculate themselves. Then the calculations will be as loyal as possible.