When creating a roof, the slope is one of the most important parameters that is taken into account in the calculations. It depends on the roofing material, as well as the local climate.
The angle of inclination of the roof is the most important parameter during construction rafter system and calculating the consumption of roofing materials for a private house. Designing a roof is a very responsible undertaking that should be entrusted exclusively to professionals who have permission to carry out such work.
However, in some cases, all preliminary calculations can be done independently, at least in order to have an idea of the expected amount of material and the possibility of realizing your architectural ideas. From this publication you will learn what it depends on and how to calculate the angle of the roof on your own, without resorting to the services of expensive specialists.
At self-construction the roof frame, most developers are guided by its design and the purpose of the under-roof space, which is fundamentally wrong. Has virtually no effect on the frame of steep roofs snow load, which means that, purely theoretically, you can save on the cross-section and pitch of the rafters. However, the wind has the greatest impact on roofs with steep slopes due to their large windage, which in practice requires the creation of a durable rafter system.
All this does not mean at all that flat roofs are better. On roofs with a low slope, snow will linger longer, which creates an impressive load on the rafter system. In addition, the angle of the roof slope affects the dimensions attic space. The steeper the roof, the more opportunities the developer has for arranging a residential attic. However, we should not forget about high cost structures with steep slopes, especially in comparison with flat roofs. Creating a sloping roof will help preserve the volume of the attic space without increasing the height of the ridge.
In addition to snow and wind load, weight also affects the frame roofing pie together with the own weight of the rafter system. If thermal insulation materials are used in the roof, then their weight is also taken into account when determining the optimal roof angle.
First of all, we should clarify the very concept of angle of inclination. This value is the angle that is formed when the horizontal plane (lay) intersects with the plane of the roof. “Laying” is nothing more than a projection of the roof slope in a horizontal plane.
In reference literature and specialized tables, percentages are used as a unit of measurement for roof slope angle. The roof slope as a percentage shows the ratio of the height of the roof (H) to the pitch (L).
At two pitched roofs akh (L) is the quantity equal to length half the span. L in pitched roofs is equal to the span length.
Rules for calculating the roof slope angle
Let's say L = 3 m and H = 1 m. In this case, the ratio will look like H to L or 1:3. This simplest example, showing the great inconvenience of determining the slope angle in this way.
To simplify calculations, a special formula for calculating the angle of roof inclination is used, which looks like this.
I = H/L where:
Let's use the data from the example above. L = 3 m and H = 1 m. Then, the calculation formula looks like I = 1/3 = 0.33. Now, to convert the tangent value acute angle as a percentage, you need to multiply the resulting value by 100. Based on this, we get: 0.33 x 100 = 33%
How to determine the angle of a roof in degrees? There are two simple ways to convert percentages to degrees:
The first method is very simple, but requires an Internet connection. There are a huge number of resources on the Internet that provide the opportunity to use an online converter.
Tables of roof slope in degrees and percentages are much more difficult to find, but they are easier to use. We publish a table of the percentage-degree ratio.
Based on the steepness of the slopes, all roofs are divided into four types:
When approaching the construction of a roof, the developer plans to use a certain roofing material. It should be borne in mind that not every material can be used on roofs with different slopes.
In roof design there is a concept - the maximum slope angle of the slopes. This value is critical to the use of a particular material. The figure below shows the minimum and maximum roof pitch values for some common roofing materials. In addition, the last column contains data on what slope slope is most often used for these materials by domestic developers.
As can be seen from the table above, there is a very significant gap between the minimum and maximum roof inclination angle.
When choosing a slope from the range of acceptable values, you should be guided solely by aesthetic considerations and material consumption.
When designing a roof, snow and wind loads on the rafter system are always taken into account. The steeper the slopes, the less snow will linger on them.
For correct calculation required structural strength, a correction factor is introduced:
To simplify calculations, maps are used that show the average snow load values for the regions of the Russian Federation.
The rules for carrying out calculations are simple: we find our region, determine the snow load, highlighted in its color, take into account the first value, multiply by a correction factor based on the estimated roof slope angle. As clear example Let's calculate the snow load for the roof of a house in Norilsk with a slope angle of 35°. So, we multiply 560 kg/m2 by a factor of 0.7. We get the snow load for of this region and specific roof structure 392 kg/m2.
To determine wind loads, maps are also used, which indicate the calculated values of wind loads by region.
In addition, the calculations should take into account:
According to the type of location of the house on the site, all buildings can be divided into three groups:
Depending on the location area and the height of the building, correction factors are introduced when designing the roof, taking into account the wind load. All factors influencing wind load are summarized in a table from which it is easy to make calculations.
For example: for one-story house in Norilsk, the wind load will be: 84 kg/m2 multiplied by a factor of 0.5, corresponding to zone “B”, which is 42 kg/m2.
In addition, aerodynamic loads acting on the rafter system and roofing material are taken into account. Depending on the wind direction, the load is conventionally divided into zones, which require different correction factors. Subscribe to our Yandex Zen channel!
If you have any questions on this topic, ask them to the experts and readers of our project.
When planning a roof, one of the main parameters determining its geometry will be the angle of its slope. Few people probably know that the slope of the roof is done for a reason. This parameter is determined not only by the desire of the developer, but also equally(and often more) the type of used roofing. If metal tiles are used, then the permissible angles will differ if, say, slate or corrugated sheets were used (Fig. 1)
Choosing a roof slope depending on the roofing material
For piece materials, such as tiles and slate, the smallest angle is considered to be 22 degrees. This prevents moisture from accumulating at the joints and seeping into the building.
For rolled materials, the minimum angle of inclination will be selected depending on the number of layers laid. With a three-layer coating, the angle will be from 2 to 5 degrees, with a two-layer coating - 15 degrees.
The small angle of inclination of a corrugated roof is considered to be 12 degrees. At small angles, according to the manufacturers' recommendations, the joints should be additionally sealed with sealants.
For roofs covered with metal tiles, the minimum angle is 14 degrees.
For roofs covered with ondulin, the minimum angle is 6 degrees.
For soft tiles a small angle is considered to be 11 degrees, and regardless of the selected angle there is required condition- installation of continuous sheathing.
Membrane coatings have a minimum angle of 2 degrees.
There is also a certain number of factors that determine the possible angle of the roof slope, the contribution of which has highest value:
* Wind rose and their strength;
*Average annual precipitation;
* Roof geometry.
Let's consider each of the factors in more detail:
:The parameter is characterized by a value indicating the maximum mass of snow that the roof surface can hold. This parameter should be taken into account in areas with heavy snow, since if it is insufficient, serious mechanical damage to the roof is possible. You can calculate the required maximum snow load using special reference books or using Internet resources. Typically, in areas where there is heavy rainfall and very heavy snowfall in winter, a slope slope of 45 to 60 degrees is chosen. This angle of inclination is specially designed, since it reduces the load, especially in winter periods, on roofing system, since the snow simply will not accumulate on the roof, but will slide down due to its own weight.
Wind rose and its strength:
And if a roof is being designed for a region characterized by strong and constant winds, the roof angle is chosen to be minimal, since this reduces the so-called “windage” of the roofing. Basically, the angle is chosen from 9 to 20 degrees.
Average annual precipitation:
However, in practice different regions Both strong gusts of wind and heavy precipitation occur, and the choice of angle should take this fact into account. Therefore, the most optimal is the roof slope, in average values, that is, from 20 to 45 degrees. It is suitable for almost any type of roofing material, for example, corrugated sheeting or metal tiles, which are very popular today.
In areas with a warm climate, where there are much more sunny days than cloudy ones, flat roofs will be more acceptable: their area is smaller than that of other types of structures, which means heating from sun rays will occur to a lesser extent. But such a structure should not be absolutely horizontal: the slope flat roof should be at least within 3-5 degrees. The minimum slope of the flat roof will ensure normal drainage of rain and melt moisture.
Roof thermal insulation:
When calculating the snow load, Special attention attention should be paid to the features of thermal insulation. This fact is due to the fact that in the case of weak thermal insulation, there is a constant outflow of heat from the heated parts of the structure to the roof, which in turn leads to melting and a decrease in the snow mass. In case of implementation of high-quality thermal insulation, the value heat flow drops significantly, which leads to more snow accumulating and, accordingly, the snow load needs to be increased.
Attention!If work is carried out to insulate structures that have not previously been insulated, it may be necessary to strengthen the load-bearing roof system, since during further operation the roof may not withstand the snow load.
Roof geometry:
The geometry of the roof has an important bearing on the roof slope angle. In the case of a single-pitch roof, its value can vary from 20 to 30 degrees, in the case of a gable roof from 20 to 45 degrees. This circumstance is due characteristic features designs.
It is also necessary to take into account that the usable area of the attic depends on the slope of the roof (Fig. 2)
Advantages and disadvantages of small roof slope angles
In the given data (recommended) of the SNiP standard, for roofs with metal tile covering, the minimum value of the slope angle is only 14 degrees. some manufacturers have managed to improve mechanical properties of its products, this made it possible to organize roofs using such materials with a slope angle of up to 12 degrees.
Manufacturers managed to achieve these results thanks to a significant reduction in surface roughness (allows snow masses slide faster) and the application of specialized synthetic coatings.
However, it should be remembered that it is not always possible to use the minimum permissible slope angle.
Let's consider positive sides small roof slope angle :
Less weight of the structure;
Less amount of roofing required;
Reduced workload indicators;
More simple circuit installation of a drainage system.
disadvantages of using a small roof slope angle:
The need to use reinforced sheathing;
The need to ensure high snow loads (due to the high probability of accumulation of heavy snow masses);
Increased requirements for such characteristics as tightness of joints. Exists high probability water leakage during precipitation;
Impossibility of equipment attic premises and attics.
Advantages and disadvantages large values roof slope angles .
Advantages of roofs with a large slope angle:
Low probability of penetration of atmospheric moisture into the joint areas of roofing materials. This circumstance is due to large angles of precipitation;
A significant decrease, and often complete absence (at increased slope angles) of the so-called. snow load and the accompanying circumstance - no need to equip snow retention elements;
Acceptability of using simple fasteners (nails and self-tapping screws);
Wide space for arranging attic and attic spaces.
Negative aspects of large roof slope angles:
Increased consumption of building materials;
Increased mass values of the entire roof;
Increased wind load (high windage);
Associated difficulties with the equipment of the drainage system (caused by the increased value of the area subject to the accumulation of precipitation).
Having considered the advantages and disadvantages of roofs with different meanings slope angles, we can draw the following conclusion: the optimal solution when designing a roof will be one where the average values of the roof slope angle will be used; such a solution will make it possible to achieve a compromise between roof efficiency indicators and the possibility of implementing architectural preferences.
In order for the roof to serve for a long time and be safe during the entire period of operation, it is necessary to prepare a high-quality project in advance. Also, don’t forget about materials, which you certainly shouldn’t skimp on, so that you don’t have to overpay, as in one well-known saying. They must not only correspond climatic conditions residence, but it is also beneficial to emphasize the architectural features of a private house. After all, no one canceled the design! But, in addition to this, the slope of flat roofs must also be taken into account. This is the same important stage, such as the selection and calculation of rafters and insulation.
The efficiency of a roof is directly dependent on its slope. And when calculating this parameter, it is necessary to take into account the region of residence, why exactly the attic is being built and the roofing materials used.
Despite the fact that during the construction of private houses, flat roofs are made in isolated cases, they have a number of advantages. And above all - low cost of work, since less quantity is spent building material in comparison with construction Their installation is not as complicated as it might seem. Flat roofing is also easy to maintain and repair.
If necessary, the roof can act as an additional platform. You can arrange a small pool on it or children's Corner. In addition, a slight slope of flat roofs will allow the installation of any equipment, often air conditioners.
The invaluable advantages of a flat roof make it in demand not only abroad, but also in Russia. This is despite the seemingly unattractive design. Currently, the inversion type of roofing is gaining popularity. But that's not what we're talking about. First you need to understand whether you need to make a bias.
Many buildings are made with a flat roof. However, it is not entirely like that and has a slight bias, since this is spelled out in the requirements of SNiP and dictated by vital necessity. Indeed, in the absence of a slope, rain or melt water will certainly begin to accumulate on the roof over time.
Even if the roof surface is perfectly flat and there should be no talk of any puddles, reality shows the opposite. Various natural factors come into play:
As a result of all this, over time the roof begins to deform. Accordingly, places are formed in which moisture and dirt, blown by the wind, begin to accumulate. If there is at least some slope on flat roofs, this probability is minimal.
It would seem, what terrible thing can happen because of water? Everyone knows that it is the basis of life for all things on earth. However, this element can easily destroy almost anything in a variety of ways.
And once we're talking about about the water that usually accumulates on the roof, then it chemical composition contains a variety of substances. These are the ones that have a detrimental effect on A in winter time the liquid generally turns into a solid state - this is where the powerful crushing force is hidden! And if there is any minimum slope flat roof - the worst can be avoided.
Many have noticed how vegetation is blooming on the roofs - the wind, along with the sun and water, are doing their job. And as you know, root system plants are a fairly strong organ that is capable of destroying almost any durable material. Over time, of course, but it doesn’t get any easier.
All parameters of a flat roof, including the slope, are regulated by the document SP 17.13330 SNiP II-26-76, which is called “Code of Roofing Rules. The Roofs” (translated from English as the roofs - roofs). This document applies to the design of roofs made of almost any material:
The amount of inclination of the slope relative to the horizon, called the roof slope, can be designated in different ways. In practice, its value is usually indicated in degrees, which is more convenient.
However, in documentation you can find the slope of a flat roof written as a percentage. However, there are significant differences between these designations. 1 degree equals 1.7%. 31 degrees will already equal 60%. In this regard, it is important to know such ratios so as not to make mistakes when making calculations.
When making a roof slope, it is worth clearly understanding the purpose of this process. Perhaps protection from the harmful effects of external natural factors is necessary. In some cases, the roof slope depends on architectural features surrounding buildings, and there is no desire to stand out strongly against their background. The material used also matters, since each has its own indicators that are acceptable during installation.
But special attention should be paid to the fact that at the maximum slope of a flat roof, the roof will act as a sail, which is not good. On the other hand, precipitation will not accumulate on such a roof. Neither drops of rain nor snow will stay long on such a surface.
The area of application of the attic also matters. It is better not to make steep slopes when arranging an attic. And in any case, financial capabilities also make their own adjustments. If you need to build a roof at an angle of 45 degrees or more, you cannot avoid increasing costs for roofing materials. Depending on this, the value of the slope angle is selected.
In addition to the fact that the slope of a flat roof is directly dependent on the type of material used, this parameter also affects the amount of thermal insulation agents. If, for example, the slope angle is small, then more thermal insulation will be required, since moisture is in no hurry to leave the sloping roof.
For arranging the roof they use different materials. This includes slate (asbestos-cement, cellulose-bitumen sheets), metal tiles, roofing felt and other options. Let's look at the most common ones.
This material has considerable weight when compared with other analogues. Therefore, it is important to correctly calculate the roof slope. This is especially critical for areas with frequent and strong winds and hurricanes. In this case, the slope angle should be as low as possible.
If you select a flat roof slope that is too high, it will swell, which will increase the load on the supporting structure. As a result, the roof may collapse prematurely.
As a rule, for such a roof the optimal slope angle will be 27 degrees. Then the roof will reliably protect the house from moisture. The minimum value is 14 degrees. Using soft material The slope angle can be reduced to 11 degrees. Only the roof in this case requires additional sheathing.
This material is considered the most popular for roof construction. It is lightweight yet durable enough to meet many property owner requirements. Carrying out installation is not particularly difficult, and you can do it on your own with the support of your loved ones.
As for the requirements for the slope of a flat roof, SP 17.13330.2011 (set of rules) allows the construction of a roof with an angle of at least 8 degrees and with a sheathing pitch of 40 cm (grade H-60, H-75). However, material grades S-8, S-10, S-20 and S-21 allow a slope angle of no more than 15 degrees. The pitch of the sheathing is from 5.0 to 6.5 cm, but sometimes a solid structure is used.
However, 8° is the minimum value that is suitable for commercial or commercial roofs. industrial buildings. For residential buildings, the minimum threshold is 10°. But as for the maximum slope, there are no special restrictions. For of this material You can build roofs even with a slope of 70°, even at a large angle.
The optimal value for the slope of a flat roof (the norms will be observed) will be 20°, which will allow snow and water to drain off in a timely manner. Then you won’t need a very large investment, and the roof can be laid in two layers. Due to this, the risk of moisture seeping through fasteners will be minimized.
Here, too, there are different values of the angle of inclination, if we take into account (like roofing felt, ondulin) or modern polymer (membrane) products. As a rule, the inclination angle is in the range of 2-15°. More accurate indicators depend on the number of layers being laid.
If it is necessary to lay a two-layer roof, the angle is 13-15°. The inclination of the three-layer coating will be smaller - in the range from 3 to 5°. When using modern membrane material, the threshold is even lower - only 2-5°.
In other words, the property owner himself chooses the slope of the flat roof; and rules) are not violated. However, one should take into account the fact that the roof must withstand loads that are not only temporary, but also permanent. The first includes precipitation depending on the season and its weight, gusts of wind. The second is the mass of the roofing material itself, which acts on the supporting structure.
In order for the roof of a building to fully perform all the functions assigned to it, it is necessary to take into account a number of parameters when creating it. One of the most important parameters The roof is its slope, which ensures the removal of precipitation from its surface and affects the ability to withstand external loads. How to calculate the slope of the roof will be discussed in this article.
To correctly calculate the roof slope, it is necessary to take into account several factors, among which the following stand out the most:
Based on these factors, you can calculate the angle of inclination of the slopes. In addition, before calculating the angle gable roof, it is worth paying attention to the recommended indicators: for areas with strong winds, a slope of 15-20 degrees is suitable, and in other cases the optimal slope is 35-40 degrees. Of course, you need to understand that the calculation of a gable roof is individual, and choosing average indicators is simply undesirable.
When designing a roof, it is imperative to carry out a number of calculations, among which there should always be a calculation of the angle of inclination of the slopes. This parameter directly affects the roof structure: as the slope increases, the snow load decreases, but the impact of wind increases, so the rafter system has to be further strengthened. To arrange slopes at a large angle, you also need large quantity materials, which negatively affects construction costs.
Before you find out the degree of roof slope, you need to calculate the operational load on the roof, which requires two parameters:
A simplified calculation algorithm is reduced to the following steps:
To understand how to calculate the roof angle, it is worth considering the calculation process for specific example. For example, the following data will be taken: the lathing has a thickness of 2.5 cm, one square meter roof weighs 15 kg, as thermal insulation material a 10 cm thick insulation is used, a square meter of which weighs 10 kg, and ondulin with a weight of 3 kg per square meter is used for the coating.
The calculation of the roof slope is carried out in accordance with the method described above. Substituting the available data leads to the following expression: (15+10+3)x1.1 = 30.8 kg/sq.m. The obtained value is quite acceptable - the average load on the roof of residential buildings is slightly less than 50 kg/sq.m. In addition, the formula contains a coefficient of 1.1, which slightly increases the actual weight of the roofing structure and makes it possible to subsequently replace the roofing covering with a heavier one.
Between the slope roof slopes and snow load there is a direct relationship. If the roof slope angle is less than 25 degrees, then the snow load coefficient is 1, and at angles ranging from 25 to 60 degrees, then this coefficient increases to 1.25. A roof with a large slope will not be subject to snow loads at all, so they are not taken into account in the calculations.
To determine the angle of inclination of the roof, you need to use the Bradis table and a simple technique: the height of the roofing structure is divided by the length of the pediment divided by two, after which it remains to find the angle in the table that corresponds to the result obtained.
The height of the roof at the ridge is determined as follows:
Using an example, the implementation of this calculation method looks like this: with a building width of 8 meters and a 25-degree roof slope, calculated coefficient is 0.47. As a result of substituting the values, we obtain an expression of the following form: 4x0.47 = 1.88 m. The resulting value is the height of the roof corresponding to the available initial data.
There is a wide range of roofing materials on the market, so there is no choice suitable option there won't be any problems. Roof coverings differ in characteristics and application possibilities, and all their parameters must be studied before measuring the angle of the roof - only in this case will it be possible to create a reliable and efficient structure.
When choosing a roofing material, you should consider the following recommendations:
Conclusion
Knowing how to find out the angle of inclination of a roof in degrees will significantly simplify the design process and allow you to create the most reliable design, which can well protect the building box from precipitation, wind and cold.
In modern private construction, gable roofs are very popular because they are easy to install and economical in cost, and their construction can be done independently. The angle of inclination of gable roofs is one of the indicators of both reliability and aesthetic appeal of the future home, so it is given paramount importance.
Gable roof
The correct choice of slope slope, chosen in compliance with building codes and technological features, will ensure maximum protection of the structure from adverse weather conditions, as well as optimize financial costs.
Angle gable roof in construction it is customary to understand the slope between the line rafter leg and a horizontal level coinciding with the wall of the building. It is measured in degrees. Less common is the percentage measurement of the slope of the slope, which is calculated using formulas based on the ratio of the sides of the triangle in percentage terms.
Option for flat slopes of a gable roof 
All roofs can be divided according to the slope slope:
It is believed that it is standard or has a slope of 45 degrees, however, this design requires more reliable fastening, since it has increased windage and is not suitable for every terrain. 
In construction practice, flat roofs with angles ranging from 0 to 45 degrees are more common. The only exceptions are the lower parts of a sloping gable roof, in which the slope is more than 60 degrees.
Examples of roofs different sizes slope slope 
Often during construction, owners set the roof slope, as they say, “by eye,” guided solely by aesthetic considerations. This is a risky decision, since it not only increases the likelihood of premature wear, but also eliminates the opportunity to optimize both the useful area of the under-roof space and the costs of materials.
When designing the overall structure of a gable roof for a house, choosing optimal slope slopes need to be given special attention, since both the functionality of the roof and its reliability will depend on this.
Example project gable roof
The following factors must be taken into account:
Different types of roofing material 
Each type of roofing differs not only in installation technology and weight, but also in the recommended minimum angle for installation, including:
Example of metal roofing material for a roof 
| Coverage type | Minimum angle in degrees | Peculiarities |
| Ruberoid and other rolled materials | 4 | This slope is acceptable when laying in three layers. For a single-layer coating, the minimum value is 25 degrees. |
| Soft bitumen roofing | 4 | The upper limit is 15 degrees, since in hot weather there is a possibility of the roof covering slipping. |
| Seam folded sheets | 5 | It is not recommended to make such a coating on slopes with a slope of more than 30 degrees. |
| Ondulin | 6 | For laying on flat roofs continuous sheathing is required. |
| Profiled sheet | 12 | At a minimum value, additional sealing of joints is required |
| Metal tiles | 14 | It is better to lay on less sloping slopes to prevent the covering from being torn off by the wind. |
| Slate | 20 | At a lower inclination, water leakage may occur. |
| Natural tiles | 22 | It is recommended to lay on steeper slopes to reduce the load on the rafter system, since the tiles have significant weight |
Drawing of a broken type roof
Relationship between the angle of a sloping roof and the amount of snow on it 
Wind load on the roof
It should be noted that a roof with steep slopes will be more expensive than a roof with flat slopes. However, the decisive factor when choosing a slope should be specifications, since they are the ones who influence the safety and durability of the structure.
In order to calculate the optimal angle of inclination of a gable roof, you must perform the following steps:
After analyzing all the data obtained, you can decide what the optimal angle will be for the gable roof of a particular house. Video tutorial on finding the height and slope of a roof.
Types of gable roofs are not limited to the classic type or the one that forms an isosceles triangle from the pediment and the slopes have the same slope.
Other types with more complex design, but for which the calculation of the angle of inclination of the sides is also relevant, are:
To design a complex roof online - the calculator will in the best possible way calculate the slope angle of each slope, since it allows you to quickly calculate and optimize this indicator based on input data, such as:
Depending on the type of roofing and the program, the data required for entry may differ in the presence of additional parameters.
The advantage of using online calculators is that by changing the entered parameters you can select best option for a specific building.
If we do the calculation complex roof manually, the following key points must be taken into account:
Examples of a gable sloping roof 
Examples of roofs with different lengths of slopes 
Example of roofs with multi-level slopes 
There are two types of different level coatings:
The calculation principle for any of the types is the same as in the previous options. 
The variety of design options for gable complex roofs requires a flexible approach when calculating the slopes of the slopes in each individual case, but the principles of calculations must remain unchanged.
Sample designs attic floor different types gable roof 
Thus, the angle of a gable roof is an important indicator when designing a roof, since the durability and safety of the building will depend on it. 
A correctly calculated roof with your own hands will guarantee future comfort, as well as optimal financial costs for construction.
