Roof 32 degrees. How to choose the optimal roof angle for snow melting? Snow and wind loads
In order for the roof of a building to be able 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 of the roof is its slope, which ensures the removal of atmospheric precipitation from its surface and affects the ability to withstand external loads. How to calculate the slope of the roof, and will be discussed in this article.
Determining the slope of the roof - what depends
In order to correctly calculate the roof slope, several factors must be taken into account, among which the following stand out the most:
- Wind loads. The slope of the slopes is very strongly influenced by the wind. In order for the roof to be able to normally resist its effects, you need to choose its angle correctly. At too large angles, the load on them will be high, but an excessive decrease in the angle can also be dangerous - a sloping roof can simply be torn off by a strong gust of wind.
- Snow and rain loads. With snow, everything is quite simple - increasing the angle of inclination simplifies its convergence from the roof surface. With a roof slope of more than 45 degrees, snow will hardly linger on it. With a small angle of inclination of the roof, a snow bag may appear, which increases the load on the roof. With rainfall, the situation is the same - if the angle of inclination of the roof is too low, then water can flow into the joints or even stagnate on the roof surface.
Based on these factors, you can calculate the angle of inclination of the slopes. In addition, before calculating the angle of a gable roof, you should pay 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 it is simply undesirable to choose average indicators.
Calculation methodology
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: with an increase in the slope, the snow load decreases, but the effect of the wind increases, so the truss system has to be further strengthened. For arranging slopes at a large angle, you also need large quantity materials, which negatively affects the cost of construction.
Before you know the degree of roof slope, you need to calculate the operational load on the roof, which requires two parameters:
- The total mass of the roof structure;
- Peak levels of snowfall typical of the region where the construction is taking place.
A simplified calculation algorithm is reduced to the following steps:
- First you need to determine the weight of one square meter of roofing cake;
- The resulting value is multiplied by the total area of the roof;
- The mass of the roof is multiplied by a factor of 1.1.
An example of calculating the roof slope in degrees
To understand how to calculate the angle of the roof, it is worth considering the calculation process for specific example. For example, the following data will be taken: the crate has a thickness of 2.5 cm, one square meter roofing weighs 15 kg, as thermal insulation material a 10 cm thick insulation is used, a square meter of which has a weight of 10 kg, and an ondulin with a weight of 3 kg per square meter is used for coating.
The calculation of the roof slope is carried out in accordance with the method described above. Substitution of the available data leads to the following expression: (15+10+3)x1.1 = 30.8 kg/sq.m. The resulting 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 roof structure and allows you to replace the roofing with a heavier one in the future.
How to find out the angle of the roof
There is a direct relationship between the slope of the roof slopes and the snow load. If the angle of the roof is less than 25 degrees, then the snow load factor is 1, and at angles ranging from 25 to 60 degrees, then this factor increases to 1.25. A roof with a large angle of inclination will not be subject to snow loads at all, so they are not taken into account in the calculations.
To determine the angle of the roof, you need to use the Bradis table and a simple technique: the height of the roof structure is divided by the length of the gable, 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 in the ridge is determined as follows:
- The first step is to calculate the width of the span;
- The resulting value is divided by 2;
- To calculate the height of the ridge, the result of the previous calculation is multiplied by a factor corresponding to a certain angle of inclination.
For example, the implementation of such a calculation method looks like this: with a building width of 8 meters and a 25-degree roof slope, the calculation coefficient is 0.47. As a result of substituting the values, an expression of the following form is obtained: 4x0.47 \u003d 1.88 m. The resulting value is the roof height corresponding to the available initial data.
The choice of roofing depending on the slope of the roof
On the market, roofing materials are present in a large assortment, so with a choice suitable option there won't be much of a problem. Roof coverings differ in characteristics and application possibilities, and all their parameters must be studied before measuring the roof angle - only in this case it will be possible to create a reliable and effective design.
When choosing a material for a roof, it is worth starting from the following recommendations:
- If the angle of inclination of the rafters is from 2.5 to 10 degrees, then stone chips or gravel coatings are best suited. In the first case upper layer coating has a thickness of 3-5 mm, and in the second - 10-15 mm.
- With a slope of more than 10 degrees, the best option would be coarse-grained or rolled materials, supplemented with bituminous waterproofing.
- For arrangement pitched roofs with an angle of inclination of not more than 20 degrees, corrugated board or sheet asbestos cement is usually used. All seams and joints between roofing materials must be treated with sealant.
- If the angle of inclination of the roof is in the range of 20-60 degrees, then it is most often covered with metal sheets. Joints of materials in this case must be sealed without fail.
Conclusion
Knowing how to find out the angle of the roof in degrees will greatly simplify the design process and allow you to create the most reliable structure that can well protect the building box from precipitation, wind and cold.
Roof slope
The slope of the roof slopes - what it depends on and how it is measured.
Such an important fact for the roof is its slope. Roof slope- this is the angle of inclination of the roof relative to the horizontal level. According to the angle of inclination of the roof slopes there are low-slope(sloping), medium inclination And roofs with steep(highly inclined) stingrays.
low slope roof the roof, the installation of which is carried out at the rate of the smallest recommended angle of inclination of the slopes. So for each roofing there is a recommended minimum slope.
What determines the slope of the roof
- From the ability of the roof to protect the structure from external factors and influences.
- From the wind- the greater the slope of the roof, the greater the value of the attributable wind loads. With steep slopes, wind resistance decreases, and windage increases. In regions and places with strong winds, it is recommended to apply a minimum roof slope to reduce the load on the roof's load-bearing structures.
- From roofing (material) - Each roofing material has its own minimum angle of inclination at which this material can be used.
- From architectural ideas, solutions, local traditions- so in different regions preferred for a particular roof structure.
- From atmospheric precipitation: snow loads and rainfall in the region. On roofs with a large slope, snow, dirt and leaves will not accumulate in huge quantities.
What is the roof pitch measured in?
The designation of the roof slope in the drawings can be either in degrees or as a percentage. The slope of the roof is indicated by the Latin letter i.
In SNiP II-26-76, this value is indicated as a percentage (%). Currently does not exist strict rules according to the designation of the size of the roof slope.
The unit of measure for roof slope is degrees or percentages (%). Their ratio is shown in the table below.
Roof slope degree-percentage ratio
You can convert the slope from percent to degrees and vice versa from degrees to percent using the online converter:
Slope Converter - Online Calculator
from degrees to percentages and from percents to degrees
Roof pitch measurement
The slope angle is measured using an inclinometer or mathematically.
Inclinometer- this is a rail with a frame, between the slats of which there is an axis, a division scale and to which a pendulum is fixed. When the rail is in a horizontal position, the scale shows zero degrees. To measure the slope of the roof slope, the inclinometer rail is held perpendicular to the ridge, that is, at a vertical level. On the scale of the inclinometer, the pendulum indicates the slope of a given roof slope in degrees. This method of measuring the slope has become less relevant, since now there are various geodetic instruments for measuring slopes, as well as drip and electronic levels with inclinometers.
Mathematical calculation of the slope
- Vertical Height (H) from the top of the slope (usually the ridge) to the level of the bottom (cornice)
- Foundation (L) - horizontal distance from the bottom of the slope to the top
Using a mathematical calculation, the value of the slope of the roof is found as follows:
The angle of the slope of the slope i is equal to the ratio of the height of the roof H to the laying L
In order to express the slope value as a percentage, this ratio is multiplied by 100. Further, to find out the slope value in degrees, we translate according to the ratio table above.
To make it clearer, let's look at an example:
Laying length 4.5 m, roof height 2.0 m.
The slope is: i = 2.0: 4.5 = 0.44 now multiply by × 100 = 44%. We translate this value according to the table into degrees and get - 24 °.
Roof slope table
Roof construction is important The final stage building a house. The roof protects the house from aggressive influences. environment, gives the building an aesthetic appearance.
Flat roofs prevail in multi-storey buildings, in private houses and cottages - pitched. The angle of the roof is an important design indicator.
Types of roofs and their dependence on the angle of inclination
There are several types of roofs, depending on the roof structure:
- shed roof- an inclined plane lying on walls of different heights.
- gable roof- consists of two slopes, is reliable and simple.
- hip roof- consists of 4 slopes with cut tops.
- hipped ceiling- several isosceles triangles connected by vertices.
If the angle of inclination of the roof is more than 10 °, then the roof is considered pitched.
What determines the slope of the roof
- from the wind
- from roofing
- from architectural ideas
- from atmospheric precipitation ( snow and rain)
The slope of the roof is the angle of the roof relative to the horizon.
The slope indicator allows you to:
- Choose roofing material
- Correctly calculate the number of snow holders
Knowing one of the values from the table, you can find the remaining values.
Minimum slope for roofing materials (coverings)
| Roof type | Minimum roof pitch | in the ratio of the height of the slope to the laying | in degrees | V % |
| Roofs made of rolled bituminous materials: 3 and 4 layers (welded roofing) | 0-3 0 | up to 5% | until 1:20 |
| Roofs made of rolled bituminous materials: 2-layer (welded roofing) | from | 15 | |
| seam roof | from 4 0 | ||
| Ondulin | 5 0 | 1:11 | |
| Wavy asbestos cement sheets (slate) | 9 0 | 16 | 1:6 |
| Ceramic tiles | 11 0 | 1:6 | |
| bituminous tiles | 11 0 | 1:5 | |
| metal tile | 14 0 | ||
| Cement-sand tiles | 34 0 | 67% | 1:1,5 |
| wooden roof | 39 0 | 80% | 1:1.125 |
Example #1.
H = 2 m
I = 2.86 m
Let's calculate the roof angle (i): 2/2.86 = 0.699. This is 35° according to the table.
Example #2
Roof slope coefficient 1.006. Find: degree of roof slope.
According to the table, this coefficient corresponds to a value of 6 ° degrees.
Calculation of the angle of the roof
The roof is one of essential elements any building. It is she who reliably protects the building from the effects of negative environmental factors, from precipitation.
Of course good construction must be waterproof, provide high-quality removal of atmospheric water, and also have high resistance to fire. At the same time, the roof should be convenient for carrying out repairs during its operation.
It should be remembered that the reliability and quality of the roof of your house will directly depend on how long the building itself will last. Currently, many homeowners prefer a sloping roof.
I must say that this design has several obvious advantages. In addition, you should correctly calculate the angle of the roof.
Benefits of a sloping roof
Simple structures, such as shed and gable roofs, hip or mansard, have always been and remain the highest quality and most reliable options. Without a doubt, the advantage of a sloping roof lies precisely in the harmonious combination of excellent quality and ease of execution.
Such a roof consists of a basic element of the roof, as well as battens and rafters.
As for the roof, it serves to protect the building from the effects of natural phenomena, snow and rain. The rafters, as well as the battens, support the entire structure, transfer the load to the walls.
Rice. 1 Calculate the angle of the roof
It should be noted that the sloping roof protects the building from precipitation due to a certain slope of the roof.
Before proceeding with the installation of a sloping (or, as it is also called, pitched) roof, it is necessary to accurately calculate the angle of the roof.
Even for those people who are not specialists in the field of roof construction, it is quite obvious: the smaller the angle of inclination, the more problems with tightness will subsequently arise.
And it absolutely does not depend on what building material you choose to cover your roof.
Factors that affect the choice of angle of inclination
Of course, you should know when calculating the angle of the roof slope, what factors need to be taken into account. So, among the most important parameters are:
- Wind. It goes without saying that a roof will offer more wind resistance at a greater slope. However, too large an angle of inclination is quite dangerous for the roof. So, for example, when the angle increases from the minimum indicator (11 degrees) to 45 degrees, the wind load increases five times. But on the other hand, when choosing a very small angle of inclination, another problem arises: with a strong gust of wind, the roof can simply be torn off;
- Snow and rain. It is quite obvious that the snow is better off the roof, which has a large angle of inclination. So, if it is more than 45 degrees, complete snow rolling is ensured. And the higher the angle of inclination, the more airtight the beautiful roof of your roof will be. This is easy to explain: the fact is that when exposed to the roof, the wind usually drives under the joints of the roof atmospheric water. But the more you make the slope of the roof, the less likely it is that water will get under the joints of the roofing materials.
Based on these factors, it is necessary to calculate the angle of inclination of the roof. For areas with strong winds, experts recommend a roof slope of 15-20 degrees, and for areas with normal winds, about 35-40 degrees.
However, it should be remembered that the calculation of the angle of inclination of the roof must be made individually for each specific building.
It should also be emphasized that when calculating, it is imperative to take into account the features of not only the climate of the area, but also the design of the structure itself.
Rice. 2 Forms of pitched roofs
Methods for making calculations
It should be remembered that choosing the right angle is a very important stage in the design of the future roof of the building. Typically, the angle of the roof is from 11 to 45 degrees, of course, there are exceptions.
In the event that the angle of inclination is increased, the snow load on the roof decreases, respectively.
But at the same time, the larger the indicator, the stronger the effect of the wind. This leads to the fact that when building a roof, more durable Construction Materials, rafters and battens. And this means that the future roof will cost you more.
roof slope calculation
Remember: the angle of inclination directly affects not only the quality, but also the amount of material for arranging the roof.
The larger the angle, the correspondingly more money the roof will cost.
A certain slope angle is attached to the roof, depending on the material chosen, as well as on climatic conditions. If there is a large amount of precipitation in the area, the slope of the roof should be steeper.
The appropriate angle of inclination of the future roof can be determined, given the expected load. How to calculate the load? To do this, you need to take into account two indicators:
- Weight of the future design;
- The snow load for the given terrain.
First of all, you need to take the weight per square meter of each layer of the roof, and then add up the indicators for all layers. The next step is to multiply the resulting result by 1.1.
An illustrative example of such calculations
Suppose your crate is 2.5 centimeters thick, and 1 square meter will weigh 15 kilograms. You plan to lay insulation with a thickness of 10 centimeters: the weight of this material is about 10 kilograms per square meter.
You also have to use Ondulin, weighing 3 kilograms per square meter.
So, our calculation: 15 + 10 + 3 * 1.1 = 30.8 kilograms per square meter. According to average indicators, for residential buildings, the load on the roof usually does not exceed 50 kilograms per square meter.
It should be noted that for a number of coatings the permissible load is greatly overestimated, however, you do not need to neglect this.
Suppose you decide to change the roof in twenty years, and the roofing carpet will be heavier than before. In this case, the same safety factor of 1.1 is required - it must be taken into account as a safety factor.
Finally, we will calculate the load from the self-weight of the roof. Let's call it H1 for simplicity. It will be equal to:
H1 = 50kg/sq.m*1.1 = 55kg/sq.m.
Learning to use the Bradis table
As for the snow load, the coefficient will depend on what angle of slope you have chosen for your roof. So, if the slope is less than 25 degrees, the factor is 1, and if it is from 25 to 60 degrees, then the factor of 1.25 is taken into account.
But in the event that you choose an angle of inclination of more than 60 degrees, you do not need to take into account the load from the snow.
If you need to find the angle of inclination of the roof, use the Bradis mathematical table (table of tangents).
The height in the ridge should be divided by? the length of the pediment, and using the corresponding value in the table, find the angle of inclination.
But in order to mathematically calculate the height of the ridge, you should calculate the width of the span of the house, divide this figure by two, and then multiply by a relative value that will be individual for certain angle tilt.
You can also use a square to determine the angle and height of the ridge.
roof pitch calculation.
Let's try to figure it out with a specific example. The width of the future building is 8 meters. We divide this value by two, we get 4 meters.
Fig. 3 Dependence of the angle of inclination of the roof on the material for the roof
We need to determine the height of the rafters in case the roof slope is 25 degrees. So, we find in the corresponding table the indicator corresponding to the given angle of inclination: it is 0.47.
We multiply half the width of our building by this relative value. We get the following calculation: 4*0.47=1.88. Accordingly, in this situation, we will need to raise the rafters to a height of 1.88 meters.
Rice. 4 Diagram of the roofing system
The choice of roofing material depending on the angle of inclination
It should be emphasized that all materials for the arrangement of the roof are combined into separate groups: according to their physical properties, technical characteristics, as well as price parameters.
- In the event that the slope of the roof is very small, and ranges from 2.5 to 10 degrees, coatings from stone chips (coarse-grained), as well as from gravel, are usually used. The top coating layer is 10-15 millimeters for gravel, 3-5 millimeters for stone chips.
- If the roof slope is from 10 degrees, and at the same time a basic bituminous waterproofing was used, it is necessary to make a top layer of coarse material. In the event that the indicator is the same, and the material is roll film, then it will be necessary to use a special paint layer for protection.
- In the event that the roof angle is up to 20 degrees, and the coating itself is made of metal corrugated board, or asbestos-cement sheets, all joints must be sealed. Is metal roofing worth it?
At angles up to 60 degrees, it is imperative to seal the joints of copper or steel roofing sheets. In this case, the joints must certainly be double.
Considering all the above parameters and making the right calculations, you can design a reliable roof that will last for a single year or ten years.
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Building any roof is not as easy as it seems. And if you want it to be reliable, durable and not afraid of various loads, then beforehand, even at the design stage, you need to make a lot of calculations. And they will include not only the amount of materials used for installation, but also the determination of the angles of inclination, the area of \u200b\u200bthe slopes, etc. How to calculate the angle of the roof correctly? It is from this value that the rest of the parameters of this design will largely depend.
The design and construction of any roof is always a very important and responsible business. Especially when it comes to the roof of a residential building or a roof with a complex shape. But even the usual shed, installed on a nondescript shed or garage, just needs preliminary calculations.
If you do not determine the angle of inclination of the roof in advance, do not find out what optimal height the ridge should have, then there is a high risk of building a roof that will collapse after the first snowfall, or all the finishing coating will be torn off from it even by a moderate wind.
Also, the angle of inclination of the roof will significantly affect the height of the ridge, the area and dimensions of the slopes. Depending on this, it will be possible to more accurately calculate the number required to create truss system and finishing materials.
Prices for various types of roof ridges
Roofing ridge
Units
Remembering the geometry that everyone learned in school, it is safe to say that the angle of the roof is measured in degrees. However, in books on construction, as well as in various drawings, you can also find another option - the angle is indicated as a percentage (here we mean the aspect ratio).
Generally, slope angle is the angle formed by two intersecting planes- overlapping and directly the slope of the roof. It can only be sharp, that is, lie in the range of 0-90 degrees.
On a note! Very steep slopes, the angle of which is more than 50 degrees, are extremely rare in pure form. They are usually used only for decorative design roofs, may be present in the attic.
As for measuring the angles of the roof in degrees, then everything is simple - everyone who studied geometry at school has this knowledge. It is enough to sketch a roof diagram on paper and use a protractor to determine the angle.
As for the percentages, then you need to know the height of the ridge and the width of the building. The first indicator is divided by the second, and the resulting value is multiplied by 100%. Thus, the percentage can be calculated.
On a note! At a percentage of 1, a typical degree of inclination is 2.22%. That is, a slope with an angle of 45 ordinary degrees is equal to 100%. And 1 percent is 27 minutes of arc.
Table of values - degrees, minutes, percent
What factors affect the angle of inclination?
The angle of inclination of any roof is affected very big number factors, ranging 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 some point, they may play their part. Determine the appropriate angle of inclination of the roof should be, knowing:
- types of materials from which the roof pie will be built, starting from the truss system and ending with the exterior finish;
- climate conditions in the area (wind load, prevailing wind direction, precipitation, etc.);
- the shape of the future building, its height, design;
- purpose of the building, options for using the attic space.
In those regions where there is a strong wind load, it is recommended to build a roof with one slope and a small angle of inclination. Then, with a strong wind, the roof is more likely to resist and not be torn off. If the region is characterized by a large amount of precipitation (snow or rain), then it is better to make the slope steeper - this will allow precipitation to roll / drain from the roof and not create additional load. The optimal slope of a shed roof in windy regions varies between 9-20 degrees, and where there is a lot of precipitation - up to 60 degrees. An angle of 45 degrees will allow you to ignore the snow load in general, but in this case the wind pressure on the roof will be 5 times greater than on a roof with a slope of only 11 degrees.
On a note! The larger the roof slope parameters, the more materials will be required to create it. The cost increases by at least 20%.
Pitch angles and roofing materials
Not only climatic conditions will have a significant impact on the shape and angle of the slopes. An important role is played by the materials used for construction, in particular - roofing.
Table. Optimum slope angles for roofs of various materials.
On a note! The lower the roof slope, the smaller the pitch used to create the crate.
Prices for metal tiles
metal tile
The height of the skate also depends on the angle of the slope.
When calculating any roof, a right-angled triangle is always taken as a guideline, where the legs are the height of the slope at the top point, that is, at the ridge or the transition from the bottom of the entire rafter system to the top (in the case of mansard roofs), as well as the projection of the length of a particular slope on the horizontal, which is represented by overlaps. There is only one constant value here - this is the length of the roof between the two walls, that is, the length of the span. The height of the ridge part will vary depending on the angle of inclination.
Knowing the formulas from trigonometry will help to design the roof: tgA \u003d H / L, sinA \u003d H / S, H \u003d LхtgA, S \u003d H / sinA, where A is the angle of the slope, H is the height of the roof to the ridge area, L is ½ of the entire length roof span (with gable roof) or the entire length (in the case of a shed roof), S is the length of the slope itself. For example, if the exact value of the height of the ridge part is known, then the angle of inclination is determined by the first formula. You can find the angle using the table of tangents. If the calculation is based on the angle of the roof, then you can find the ridge height parameter using the third formula. The length of the rafters, having the value of the angle of inclination and the parameters of the legs, can be calculated using the fourth formula.
The roofs of private houses, as a rule, always have slopes - this roof design is the easiest to operate and maintain. Water and snow are better and faster to leave such roofs, which guarantees excellent waterproofing. Yes and appearance private home becomes more attractive.
In addition, there is an additional room in the attic, which can be used for living and building an attic or for numerous household needs.
Factors affecting the shape of the roof
To make the roof reliable and comfortable, it is necessary to correctly calculate the angle of the roof slope, which depends on many reasons. First of all, these are the climatic conditions of residence and the characteristics of the roofing material. Natural conditions affecting the size of the roof slope:
- as the roof slope increases, the wind load on the roof structure increases. For example, if the angle of inclination is increased from 10 degrees to 45 degrees, then the load on the structure due to wind will increase five times. If the angle is made small, less than 10 degrees, then there is a high probability of a breakdown of the coating sheets due to a strong wind that falls under the joints;
- atmospheric precipitation in the form of rain and snow also affect the slope of the roof. With an increase in the slope, precipitation better descends from the roof slopes. The greatest snow load in winter time occurs on slopes with a roof slope of about 30 degrees. At an angle of 45 degrees, the snow will melt completely.
With a small slope of the roof slopes, as a result of strong gusts of wind, water can get under the joints of the coating.
In the question of what angle of the roof slope needs to be made, the type of roofing matters:
- When using metal tiles as a roofing material, it is necessary to take into account the considerable weight of this coating. Therefore, the angle of inclination of the roof should not be very large. This is especially important in areas where permanent and strong winds, as the mechanical load on the roof structure increases. For this coating, the minimum slope angle is approximately 22 degrees.. In this case, moisture will not accumulate, but will be effectively removed from the roof. In addition, the joints of the coating will be reliably protected.
- The professional flooring is the most popular roof covering now for private houses. It is lightweight, easy to install and maintain the roof. Minimum Angle roof slope using this material is 12 degrees.
- Using roll materials, they are also called soft roof, the angle of inclination of the slopes depends on the number of coating layers. For a coating that consists of two layers, the minimum angle of inclination is up to 15 degrees. For three layers, this value should be between two and five degrees. If the roof needs to be covered with a membrane coating, the angle of inclination should also be between two and five degrees.
From the above, we can conclude that the decision on the optimal angle of the roof slope depends on the natural conditions, the type of roofing material and the capabilities of the owner of the house.
With a large slope, the consumption of materials during the construction of the roof increases.
In addition, the type and pitch of the crate depends on the slope of the roof slopes. The smaller the slope of the roof, the smaller the step of the crate should be.. For minimum angles, it is approximately 35 to 45 centimeters.
- with a roof slope of up to ten degrees, roofing can be done using crumbs of stone and gravel;
- if the roof slope is more than ten degrees, then waterproofing using bituminous materials should be used. For rolled materials, it is necessary to use an additional protective coating;
- when using corrugated board and slate, sealing of joints and seams is recommended, the joints should be double.
- If the amount of precipitation in the area where the residential building is located is high, then the angle of inclination is best done at 45 degrees. With a minimum amount of precipitation, the roof slope can be made at 30 degrees. In strong and frequent winds, the angle of inclination should be between 15 and 20 degrees. If the wind loads are small, then it is better to make a roof, the angle of inclination of which is from 35 to 40 degrees.
When calculating the angle of inclination of the roof, it must be taken into account that the higher the average annual temperature and the less precipitation, the more flat the roof can be built.
It should be taken into account that the type and design of the drainage system of the whole house depends on the slope of the roof.
The choice of the angle of inclination of the roof, depending on various factors
When determining the slope of the roof does not exist ideal solution suitable for all climate requirements. Here it is important to find best option, on which the consumption of materials and the cost of funds depend.
The larger the roof area, the more expensive it is.
The recommended roof slope angle is between 20 and 45 degrees.. With its increase, it is necessary to take into account the creation of additional structures to strengthen the entire structure. And a decrease in the angle will lead to additional costs of materials to ensure normal waterproofing of the roof of the house.
The reliability of any building, as well as the comfort of living in it, depend mainly on how well its roof is arranged.
And one of the criteria for the quality of the roof is its slope.
Since the amount of roofing material also depends on its size, the choice of the angle of inclination and its preliminary calculations are made before the purchase of the selected roofing material begins.
What influences it
Depending on the magnitude of the slope of the roof slopes, the peculiarity of its operation depends.
It is customary to distinguish 4 types of roofs:
- high, with an angle of 45-60 degrees;
- pitched, with a slope of 30 to 45 degrees;
- gentle, the slope angle of which is 10-30 degrees;
- flat. A slope of 10 degrees or less.
The choice of the value of this parameter is influenced, first of all, by natural factors that are characteristic of the area.
Strong wind exerts the greatest pressure on high roofs.
Because such roofs, due to the large angle of inclination, have a very large area.
A large surface area has a very high windage.
Accordingly, the load on the entire structure of the truss system is very high.
And if you decide to arrange a high roof with a very large slope, then you should take care of a very solid foundation.
However, in areas where strong winds prevail, it is unsafe to arrange and flat roofs.
With this type of roof, the lower part of the slope will be high blood pressure with strong wind.
And if the roof fastening is weakened, the entire structure may fail.
Therefore, in areas where strong winds are frequent, it is recommended to arrange pitched roofs with a slope of 25 - 30 degrees.
If the wind force is small, then the slope of the roof can be 30-45 degrees.
If in the area where the house is being built, during the cold season there is heavy snowfall, then a roof with a large slope angle should be built.
In this case, the high roof is out of competition.
On roofs with a large slope, snow does not linger.
It is for this reason that in all northern countries the roofs on buildings are very high (Sweden, Finland, Norway, etc.).
The smaller the angle of the roof slope, the longer the fallen snow will be on the slopes.
The more weight will affect the entire structure.
If the design of the truss system is made with a large margin of safety, then some layer of snow on the roof is not bad.
It provides a little extra insulation.
However, if the design of the truss system of the structure is not designed for a large load, then there may be big problems.
Choosing a slope depending on the roofing material used
Gone are the days when only two types of roofing materials were used for covering: tiles and slate.
There are a lot of roofing materials today!
Each material has its own individual specifications and this must be taken into account when calculating the required value of the angle of inclination.
After all, it may happen that the material you like in terms of its parameters simply does not fit.
Minimum Tilt Angle
There is a concept of the minimum value of this parameter.
For each of the materials, this parameter is different.
And if the angle of inclination obtained as a result of your calculations turns out to be less than the minimum value for the roofing material you have chosen, then you cannot use it for roofing.
In the future, a lot of problems can arise if you violate this rule:
- for any piece of stacked roofing materials, such as tiles or slate, the minimum slope is 22 degrees. It is with this value that moisture does not accumulate at the joints and moisture does not seep inside the roof;
- the angle of inclination for rolled materials (roofing felt, bicrost, etc.) depends on how many layers you plan to lay. If there are three layers, then the slope can be 2-5 degrees. If there are two layers, then it needs to be increased to 15 degrees;
- corrugated board manufacturers recommend that when constructing a roof from this material, arrange a slope angle of 12 degrees. Decking can also be used at lower values, but in this case it is necessary to glue the joints of the sheets with a sealant;
- For metal tiles the value of this parameter is 14;
- for ondulin - this is a value of 6 degrees;
- minimum slope for soft tiles equals 11 degrees. But at the same time, a prerequisite is a continuous crate;
- for membrane roofing there are no strict requirements for the minimum value of this parameter.
It's about the minimum values.
My advice is to stick to these rules.
So that in the middle of winter you do not have to re-roof the entire roof.
Now about the optimal values
If it rains and snows often in the region, then the roof will be optimal, the angle of inclination of the slopes of which will be 45 - 60 degrees. After all, it is necessary to remove the load from water and snow from the roof as soon as possible.
Because the strength of the truss system is not unlimited.
And thanks to the large slope of the roof, rain and snow will descend as quickly as possible.
If in the region where the house is built, there are constantly strong winds, then the roof is treated differently.
With a smaller slope, its windage decreases.
And there is no exorbitant load on the roofing material and rafters.
Also, the roof will not tear off during sudden gusts of wind.
In this case, the optimal angle of the roof slope is 9 - 20 degrees.
Very often in the region there is both snow and wind.
For example, the Orenburg region.
In this case, choose the average value of the angle of inclination.
As a rule, its value is in the range of 20 - 45 degrees.
If you pay attention, most pitched roofs have exactly this meaning.
We calculate its value
For lean-to
We draw a perpendicular L sd along the wall, originating at the point where the short wall ends and resting on the wall with the maximum length.
The result is a right triangle.
If the length of the wall L cd is 10 meters, then in order to obtain a slope angle of 45 degrees, the length of the wall L bc must be equal to 14.08 meters.
For gable
Calculation principle for gable roof similar to the previous principle.
Consider an example
Leg C is half the width of the building.
Leg a is the height from the ceiling to the ridge.
The hypotenuse is the length of the slope.
If we know any two parameters, then the angle of inclination can be easily calculated using a calculator.
If the width is 8 and the height is 10 meters, then the formula should be used: 
cos A = c+b
Width c = 8/2 = 4 meters.
As a result, the formula looks like this:
cos A = 4/10 = 0.4
According to the Bradis tables, we find the value of the angle to which the given cosine value corresponds.
It equals 66 degrees.
For a four-slope
And again, you can not do without roulette and Bradis tables.
Knowing several parameters, you can easily calculate others.
Including the angle of inclination of the hipped roof.
It should be remembered that all dimensions must be taken as accurately as possible.
And to measure the slope of an already built roof, a special tool will help - an inclinometer.
After all, if you make a mistake, then the angles of inclination, length and area may not be correct.
This means that you will make a mistake in the amount of material required or the strength of the roof will be lower than planned.
Watch a video about the slope of the ramps.
Sergey Novozhilov - roofing materials expert with 9 years of experience practical work in area engineering solutions in construction.
