Which roof angle is best? Calculation of the minimum slope for a roof made of corrugated sheets

Every potential homeowner should know how to calculate the roof pitch country house or a dacha, because not only the cost of roofing material and construction work, but also the safety of living itself depends on the angle of inclination. The correct geometry of the roof allows you to save on building materials and create a structure that prevents the accumulation of snow caps and ice blocks on the roof, the collapse of which can damage both the structure and household members. Therefore, in this article we will present methods for calculating the optimal angle of inclination of the slope.

IN residential buildings There are four main types of roofs that can be used. Single-pitch option will do extension or outbuilding, but does not look at all on the main building. The only real plus of this type- This minimum consumption roofing material, but there may be safety issues. Almost all the fallen snow is retained on the flat slope, so such roofs are cleaned manually by climbing onto the slope.

For two pitched roof no complex frame required

The gable version, built on the basis of two slopes, allows you to create safe roof, from which snow caps of any thickness will come off. Besides, gable roof it looks very presentable and does not require the construction of a complex frame. The hip version and its derivatives are a hipped structure with complex frame and relatively low consumption of roofing material. Not all specialists are capable of building such a structure - the abundance of joints (especially in the attic or half-hip version) requires more skill and time to assemble the roof. After all, in case of an error, it will flow, flooding a residential building.

The multi-gable option is a multi-slope structure of complex shape. This option can only be built by experienced roofers. A multi-gable roof requires more building materials and time, making this the most expensive option available. Moreover, a complicated form (such a roof has five or more slopes) can both decorate and overload the exterior of a home, creating a feeling of excessive complexity, which causes a feeling of irritation in people with delicate architectural taste.

And if you choose according to the ratio of the simplicity of the design and the calculations carried out, the volume of building materials used and the presentability of the exterior, then the best option there will be a gable roof with two slopes. It is this design that we will consider when trying to understand how to calculate the angle of inclination of the roof for a country house or cottage.

Before calculating the optimal roof geometry, you should become familiar with roof design to understand the process and terminology involved. This will not take much time, since the option we have chosen consists of 7 original elements:

1. 1. Mauerlat – logs at the base of the frame, which are laid on a load-bearing wall.
2. 2. Ridge - the upper edge of the roof. In our case, this is not exactly a detail, but a place where the roof slopes meet.
3. 3. Beams - beams under the ridge of the roof, laid at the same level as the mauerlat.
4. 4. Racks – vertical beam, connecting the bed and ridge run(beam under the top edge).
5. 5. Rafters - beams resting on the Mauerlat and ridge girder of the roof.
6. 6. Lathing - alternating longitudinal slats laid on top of the rafters and forming the basis of the frame for the roof slope.
7. 7. Strut - a beam laid at right angles to the rafters and stretched to the point where the post and the beam meet.

At the base of the frame there are logs that are placed on load-bearing walls(mauerlat)

The total number of elements depends on their functional purpose. For example, there is always one bed near the roof, and at least two for the mauerlat. The number of rafters is always paired and equal to the number of struts. Well, the number of racks is determined by dividing the sum of the rafters by two. After all, for every couple rafter legs there is only one stand. And now about the most important thing - the roof angles we calculate are formed by the plane of the base (horizontal) and the line of the rafters laid at an angle to the mauerlat.

Technically, the slope of the roof can vary from 0 to 90 degrees. In the first case, we will get a flat roof, and in the second, a pitched roof (the second slope should be less than 90°).

Snow load - important factor to determine the roof slope angle

The geometry of the roof with two slopes and angles differs from the limit values, but cannot be any; the possible value of the slope of the rafters is determined under the influence of the following factors:

• Wind and snow load. Correct slope should help save on frame construction. After all, the higher the load, the more rafters, racks and struts will be needed.
• Like roofing. Each type of structural roofing material imposes restrictions on the minimum and maximum value of the calculated angle.
• Cost of building materials - the lower the slope, the cheaper the structure. After all, if the roof slope is zero, then the area of ​​the slope is equal to the dimensions of the roofing. And as the slope increases, the area of ​​the slope also increases. And if you have chosen an expensive building material, then the correct slope will help you save on its purchase.
• The dimensions of the structure itself - the height of the ridge should correspond to the distance between the mauerlats. Otherwise, you will get distorted proportions and ruin the aesthetics of the house’s exterior.

Moreover, all the factors mentioned above are interrelated, so they are considered only as a whole when calculating the optimal roof geometry. How to do it? We will talk about this below in the text.

Optimal tilt angle gable roof should not lead to an increase in snow and wind loads, distort the exterior of the house and force the purchase of more roofing and building material. Therefore, to determine its value, we will sequentially move through all the mentioned parameters, selecting optimal size for each of them. After which we will calculate the slope based on the average value and acceptable limits for the roofing material.

The most optimal angle of inclination of a gable roof is about 37 degrees

For wind load optimal slope– this is 0 degrees. In this case, it does not add height to the building. Therefore everything multi-story houses have a flat roof. In addition, zero slope gives minimum area stingray In this case, it is equal to the area of ​​the ceiling (ceiling or floor). For snow loads, the optimal angle is 60 degrees. Roofs with such angles do not accumulate snow on the slopes, which makes it possible to ignore the snow load as such. As a result, the average slope in snow and wind is 30 degrees ((0+60)/2). This value lies beyond the threshold value (25 degrees), which allows reducing the calculated snow load by 30 percent and does not increase the wind load.

The optimal exterior gives the ratio of the height of the rack and the distance between the mauerlat and the floor in the proportions of 3:4 or 1:1 (in the case of an exploited roof). That is, the tangent of the slope angle in this case will be equal to 0.75 (3/4) or 1.0 (1/1), which corresponds to angles of 37 and 45 degrees. The average angle for the exterior and wind/snow load is 37.5 degrees ((30+45)/2), which corresponds to the optimal proportion of 3:4 (the ratio between the height of the ridge and half the width of the building on the gable side).

That is, the optimal slope angle should be as close as possible to 37 degrees. Moreover, in snowy regions it can be brought closer to 45 or even 50°, and in the southern regions it can be reduced to 30°. After all, snow and wind loads even in middle lane Russia have a ratio of 4:1. Per square meter roofing structure on average there is about 200-210 kilograms of snow or the equivalent of 35-40 kilograms of wind. Therefore, counteracting snow in our latitudes will be more relevant.

From point of view roofing materials an angle of 37° allows you to use such varieties when arranging the roof as two-layer roofing felt (roofing felt), galvanized with seams, tongue-and-groove tiles, slate.

As you can see, at this angle you can choose a material to suit every taste and budget. From the position rational use space, this angle is also beneficial due to the fact that an attic equipped inside the roof will give at least 4 square meters usable area for each meter of bed length, and the area outer covering will fluctuate within 13 m 2 per meter of ridge length. That is, 37° will also be beneficial from an economic point of view.

The reliability of the building and the comfort of living in it depend on the quality of roof construction. Its design is selected optimal for local operating conditions. Special meaning has such a parameter as the slope of the roof, which will be discussed further.

The angle of the roof slope depends not only on its design and the features of the facade of the house, on the selected roofing material, but also on other factors. It is necessary, first of all, to take into account the climatic conditions of the area where the building is being erected. Where the number of drops in winter time precipitation is high, a large roof angle is preferable (within 45-60 degrees): this contributes to better snow melting, which means reducing the load on the roof. It also becomes less likely that the surface of the floor will freeze due to compaction of snow covers.

If the building is being erected where weather with strong winds prevails, it is advisable to choose minimum angle roof slope to reduce the windage of the structure. Otherwise, the structure is in danger of rapid destruction. Most often, the tilt range in this case is 9-20 degrees.

The greater the slope of the roof slope, the easier the snow cover comes off it.

But basically, the optimal roof slope angle is selected 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.

Types of roofing structures

Utility and utility buildings are often built with a pitched roof: it is easy to install and does not require large expenses. In essence, such a building has different heights walls with ceilings laid on them. The slope of the ceiling is selected within the range of 9-25 degrees, which is well suited for corrugated sheets and metal tiles. This design requires ventilation of the under-roof space.

But the most popular is the gable one: two planes located at an angle are connected along the ridge line. Other (end) planes are vertical and are called pediments. They may have doors to access the balcony or external staircase.

There are many options for roofing structures

Hip ceilings, the most popular representatives of which are hipped ones, are aesthetically very attractive. In such cases, especially in more complex structures, the slopes can be any: it depends on the chosen design and personal preferences of the developers. The advantage of hip roofs is that there are no restrictions on the use of roofing material.

Option hip design– attic: attic space It is used as a residential building, so the requirements for insulation are very high. The free space under the ceiling is formed due to the high angle of inclination of all slopes, in which the presence of skylights.

Dependence of roof structure on floor material

Before choosing a roofing material, you should study its technical characteristics: this will help you optimally approach the issue and choose the most reliable one. In addition, there is a rule that determines the dependence of the slope angle on the roofing material used.

We list the main ones:

When choosing the slope value, you should take into account the strength characteristics of the roofing structure: the safety margin should be enough not only to withstand its own weight and the weight of the roofing material, but also for external loads (gusts of wind, snow). Also, the type of sheathing for laying most materials also depends on the slope of the slope: for small values ​​of this parameter, either a continuous sheathing or with a small pitch (350-450 mm) is installed. When erecting any roof, especially a flat one, it is necessary to install a system of slopes and drainage. If the area is particularly large, additional drainage will be required.

Calculation of the angle of inclination

The design must meet the following requirements: be strong enough, provide reliable protection from precipitation, have good thermal and sound insulation. It is also important that there is access for repairs and maintenance. How to calculate the angle of the roof so that all these conditions are met? Experts recommend using simple options its devices, which include single-pitch, gable, hip (and half-hip), and attic.

Roofs can have a design of any complexity, with different slope angles

Single-pitch roofs are most convenient for verandas, outbuildings and outbuildings. The principle of creating a single-pitch roof is the same as other types: rafters and sheathing are installed, after which the roofing material is laid. The latter plays a decisive role: for corrugated sheeting an angle of 8-11 degrees is required (it is better to do 20), for metal tiles - at least 25, for slate and seam roofing - 35 degrees.

If climatic conditions allow, it is better to make a roof with a slope of 45 degrees: this will allow you to neglect calculations related to the mass of snow. This is an almost ideal pitched roof: the angle of inclination will not complicate its installation and will facilitate maintenance (snow will not accumulate on its surface). But in this case, it will be necessary to strengthen the rafters and sheathing, since the wind pressure on the structure increases 5 times. It should also be taken into account that this will require high costs for materials - approximately 1.5 times.

Roofing material must be selected depending on the roof slope

As can be seen from the graph, each slope corresponds to a certain group of roofing waterproofing materials. There are 11 of them in total, with the inclined lines corresponding to the angle of inclination of the slope. The thick line indicates how the height of the ridge relates to ½ of its depth. It can be seen that the segment h equal to half horizontal segment indicated by the fraction ½. The numbers at the tops of the semicircular scales correspond to the angle of inclination (in degrees), the vertical scale also indicates in percentage. When choosing any roof configuration, you should adhere to these recommendations and purchase roofing materials suitable for your chosen option.

In order to make it clear how the roof slope angle is calculated, we will give an example of calculating the smallest slope angle of a roof with tile waterproofing. On the graph we find a semicircular curve corresponding to this covering: this will be the curve indicated by the number 2. Tracing it to the point of intersection with the vertical scale, we find that the minimum slope of such a roof is 50%.

Taking into account the fact that the slope of the slope is the ratio of the height of the ridge to ½ of its depth, we calculate the slope. That is, with a ridge height h = 4 m and a slope equal to L = 15 m, the slope will be determined as h: (L/2) = 4: (15/2) = 0.53. To display it as a percentage, multiply the result by 100 and get 53%. This value of this parameter guarantees good drainage of rainwater. The minimum slope in the valley is 1%.

Features of calculating a gable roof

Gable roof is the most successful and widespread design. There are several reasons for this: high reliability, relative simplicity, low cost design. When constructing a roof, not everyone correctly chooses the optimal angle of inclination of a gable roof.

In areas of strong winds, it is necessary to calculate the gable roof so that its slope does not cause too strong wind loads. The greater the angle of inclination of the structure, the higher its windage.

You cannot reduce it to values ​​​​less than 25 degrees: precipitation will be less easily removed from the roof, and dampness may appear in the under-roof space. Making it larger than 60 degrees is also not recommended: a strong impulse of faith can destroy the roof. The roof does not have to have symmetrical slopes: if you orient the building with a more gentle slope to the south, the roof will dry better after rain.

Conditions for using roofing materials depending on the slope angle

Useful attic area and drainage system

The usable area of ​​the attic space depends on the roof structure: the greater the slope angle, the larger the area and vice versa (this is clearly shown in Figure 2). When constructing an attic, you have to make a compromise between the area that can be easily used, the cost of building a roof and the strength of the structure.

The method of removing precipitation can also be different. There are external or internal organized and unorganized - only external. The latter involves installation drainpipes and gutters, while wall and suspension systems mounted on roofs with a slope greater than 15%. The gutters are attached with a minimum slope of 3 degrees, their sides are made with a height of about 120 mm.

It depends on the angle of the roof effective area attics

The distance between the pipes should be no more than 23 m. The cross-section of the pipe should ensure normal drainage of water and is selected depending on the area of ​​the slope. External drains of an organized type are more suitable for areas with a warm climate. Internal gutters are used for cold climates. Such systems consist of a funnel for receiving water, a riser, an outlet and a discharge pipe. The main condition is that water drainage must be ensured at any air temperature.

Installing a roof is a very important task that requires the participation of highly qualified workers. Installation errors can cost home owners dearly. To avoid troubles, roofing work should be entrusted to specialists with sufficient experience: this will guarantee the reliability of the building and the comfort in it.

Metal roofs are a practical and popular solution for the construction of private low-rise buildings. This roofing material is characterized by high bearing capacity, resistance to mechanical damage, external environmental factors and intense loads. The durability and reliability of the finishing coating depend not only on the quality; these characteristics are influenced by the design of the roof, including the correctly selected minimum slope. In this article we will tell you how to choose the right slope angle and check it for compliance with SNiP.

The roof slope is an important design parameter, which indicates the angle formed by the floor plane and the roof slope. This indicator is expressed as a percentage or degrees. It is calculated as the result of dividing the height of the ridge by half the width of the building. The angle of inclination of the slope depends on the technical and operational properties material and is regulated by SNiP and manufacturer’s instructions. It depends on:

1. Possibility of using one or another type of roofing covering.
2. Design, composition and cross-section of rafter frame elements.
3. The ability of a roof to effectively drain precipitation.
4. Cost of roofing work.
5. Weight of the roofing pie.

Note! If the slope of a metal tile roof is increased from 22 degrees to 45 degrees, the area of ​​the slope will increase by 20%, which will affect the cost of materials (finish coating, waterproofing, insulation, wood), as well as the weight of the structure. It is necessary to decide on the optimal angle of inclination during the preparation of the project in order to correctly determine the load on the foundation.

Optimal values

Metal roofs are relatively new constructive solution, therefore, the technology of its installation and operation is not clearly regulated by SNiP. Information about what the minimum roof slope should be is provided by the manufacturer, since this indicator directly depends on technical characteristics the material itself. This indicator is calculated in accordance with the thickness, load-bearing capacity and method of laying the roofing.

• According to SNiP, the minimum angle of inclination of a metal tile roof, if the length of the slope is 6 meters, must be at least 14 degrees.
• The permissible slope for a metal roof is in the range of 14-45 degrees.
• The optimal angle of inclination, which ensures effective removal of precipitation with less impact on the slopes, should be 22 degrees.

Important! The minimum slope of a metal tile roof allowed by manufacturers is 11 degrees. Some brands of material can be laid even if the slope is 10 degrees steep. A reduction in this indicator was achieved by the use of new, smoother polymers and more durable steel for the production of roofing coverings.

Slope selection

It can be difficult for a non-professional builder to correctly select the minimum angle of inclination of a metal tile roof. This indicator, in addition to SNiP requirements and manufacturer’s recommendations, is influenced by other factors that also need to be taken into account. When choosing the steepness of the slope, the following are taken into account:

Please note that the choice of slope slope depends on the roof design. Optimal slope angle pitched roof from metal tiles is 20-30 degrees, and gable tiles - 20-45 degrees.

Features of roofs with a small slope

The minimum recommended pitch for a metal roof is 14 degrees, however experienced craftsmen can efficiently lay this type of roofing material, even if the slope of the slopes is within 10-14 degrees. To increase the reliability of such a design and reduce the risk of leaks, the following measures must be taken:

1. Increase the frequency of the sheathing slats and reduce the pitch between the rafters. To minimize the risk of roof collapse due to intense snow load, it is necessary to strengthen rafter frame structures and install frequent or continuous lathing.
2. Increase overlaps. Manufacturers recommend when installing metal tiles to make a horizontal overlap of 8 cm, and a vertical overlap of 10-15. To eliminate the possibility of leakage in structures with gentle slopes, you can increase the overlap at the joints of the sheets.
3. Insulate joints. To prevent the penetration of melt and rain water between the joints of the sheets, you can treat the seams silicone sealant, although this measure has a limited duration.

Experienced craftsmen claim that the easiest way to make a roof made of metal profiles reliable is to follow the manufacturers’ recommendations and strictly adhere to the recommended angle of inclination.

Video instruction

Roof of the house

The roof is structural element building, which is responsible for its protection from exposure external factors. It must successfully withstand precipitation in the form of rain, hail, snow, heavy winds and destructive hurricanes. The correct roof pitch plays a big role in quick removal from the roof of water and snow cover. In combination with high-quality waterproofing, it provides excellent protection for the entire structure, including interior spaces.

Not only these indicators, but also its long-term operation and strength will depend on the correct slope of the roof. How to make the calculation correctly, what factors to take into account, how to calculate it for roofs with different coating– all these questions will be discussed in this article.

About the factors influencing the calculation of the roof slope angle

Roofs, as already written on our website, have different shapes and the number of stingrays. They come in single, double and quadruple slopes. The angle of the roof depends on the number of slopes on your house.

Construction works roof installation may be delayed if you do not decide in advance what material you are going to use for the finishing coating and what angle of inclination of the roof. It must be remembered that these two concepts are closely intertwined, since the type of roofing material proposed will be taken into account when calculating the angle of inclination of any pitched roof.

Let us dwell on the factors that are taken into account when calculating the angle of inclination of the roof.

For example, when choosing the angle of inclination of a pitched roof within 9-20 degrees, you will need to take into account factors such as

• finishing coating material;
• existing climatic conditions;
• functional purpose of the building.

In the case where the roof has two or more slopes, then not only the above factors and the area in which the house will be built will be taken into account. It will be necessary to take into account the purpose for which the attic space is being installed. If it is not intended for housing, but should be used to store temporarily unused things and objects, then you should not arrange a large room for these purposes (we are talking about the height of the ceiling). When the owners plan to turn the attic into a living space in the form of an attic, then the need arises to install a good roof with a significant slope.

In those regions where strong winds are not uncommon, the roof slope is minimal. Therefore, it is not subject to such strong wind influence. It is also not recommended to make roofs without a slope. Such coatings can be installed in regions with a large number sunny days and little chance of precipitation.

Wind resistance with a high roof is much greater than with a low one. However, with a very small slope, there is a possibility that the wind could tear off the finish. It turns out that with very steep roofs there is the same danger as with roofs that do not have a slope at all. It is therefore recommended to choose the following roof slopes - in light winds it can range from 35 to 40 degrees, in strong winds the optimal roof slope angle is 15-25 degrees.

In areas where precipitation occurs in large quantities (we are talking about snowfall, hail and rain), the angle of inclination can be increased to 60 degrees. It is the most suitable because it allows you to minimize the load on the roof from snow cover, as well as melt water and large quantity moisture during rain.

Taking into account all of the above, the roof inclination angle is calculated based on the range from 9 to 60 degrees. Designers, as a rule, make appropriate calculations and usually settle on values ​​that range from 20 degrees to 45.

Why is this roof angle attractive? The fact that you can use any roofing material - metal tiles, corrugated sheets, slate, etc. However, each finishing material has its own requirements, which are taken into account when constructing the roof structure.

1. The use of built-up materials is most suitable when the roof has a slope of 0-25%. When the slope is 0-10%, the material must be laid in three layers. If the angle of inclination is in the range of 10-25%, you can get by with one layer, but the material must have a sprinkle.
2. Roofs with a roof slope of up to 28% are covered with asbestos-cement corrugated sheets (slate).
3. Tiles are used when the roof has a slope of at least 33%.
4. The steel covering is laid on the roof with a slope angle of less than 29%.

Material consumption directly depends on the roof slope. The larger it is, the greater the consumption of finishing material. Consequently, flat roof in this regard, it will cost less than a roof with a slope of 45 degrees.

If you know the roof slope, then calculate the amount required material is not difficult. The same can be said about the height of the roof structure.

Let's look at each specific form roofing covering.

Metal roofing

Compared to other roofing materials, metal tiles have considerable weight. Therefore, when constructing a roof structure using such a finishing coating, you should take into account all the nuances and try to build it so that it has a minimum roof slope angle.

This question deserves special attention in areas with very strong winds. As is known, the load from the wind exerts a strong and negative impact. In this case, the calculation of the roof structure must be done especially carefully. When the angle of the roof is large, “swelling” of the roof may occur, which will lead to an increase in load, which will affect the entire structure. In turn, this can lead to premature failure of the roof.

Roofs that are covered with metal tiles must have a minimum slope angle of 22 degrees. Empirical data suggests that this indicator prevents the accumulation of moisture at the joints of the roofing. They are protected from unwanted seepage of water in the form of melted snow or rain.

Important! The minimum roof slope, when such a need exists, can be at least 14 degrees. If used as a coating soft tiles, then the minimum value decreases to 11 degrees. In this case, it would be correct to arrange additional continuous sheathing.

Corrugated roofing

It is known about corrugated sheeting that it occupies the place of one of the most popular roofing materials. Everyone knows its advantages in the form of low weight and ease of installation. Fastening profiled sheets to the roof is not difficult.

Important! It should be taken into account that when installing such a roof, the requirements for the minimum roof slope angle are more than 12 degrees (you should look at the manufacturers' recommendations).

Roofing using rolled “soft” materials

When the roof is made from soft species roofing covering, then we are talking about roofing felt, ondulin, polymer (membrane) roofing coverings. When deciding how to calculate the roof pitch, consider the following:

1. Number of covering layers. Depending on them, the angle of inclination of the roof structure can be from 2 to 15 degrees.
2. When covering in 2 layers, it would be good to stop at a roof angle of 15 degrees. For a three-layer one, it is enough to have a slope within 2-5 degrees.
3. Membrane coverings, which are optimal for any type of roof, including the most complex in its geometry, are placed on roofs that have a slope of 2-5 degrees.

Without a doubt, the angle of the roof will be chosen by the owner of the building. He must take into account that the roof is designed for temporary and permanent loads. Temporary include precipitation and its weight. These include wind, which puts pressure on the roof structure and the finishing coating itself. When constant loads are mentioned, we are talking about the weight of the roofing structure itself and the finishing coating material.

A structural element of the roof such as sheathing—its type, pitch, and design—depends on the slope of the roof. For example, the lower the angle of inclination, the shorter the pitch of the sheathing in the roofing system should be. The minimum roof slope requires a sheathing pitch of 35-45 centimeters.

One of the main questions is the amount of material for the finishing coating that needs to be calculated and purchased. The following trend can be seen here - a larger roof slope requires more material consumption.

I would like to offer a few practical advice which will be useful when selecting roofing materials:

• with a slight roof slope (less than 10 degrees), the roof can be covered with a material containing stone chips or gravel (5 mm thick for chips and 15 mm for gravel).
• when the roof slope angle is more than 10 degrees, a device will be required basic waterproofing from bitumen. In the case of using roll materials, it is necessary to use additional protection. This coating is usually a paint.
• covering the roof with roofing material such as corrugated board or asbestos cement sheets, provides sealing of butt seams. The joints in this case are made double.

We calculate the angle of inclination of the roof

Calculation of the roof slope angle depends on the height of the ridge. How high the roof will be at the ridge depends on the functional purpose attic space.

When an attic is made into a full-fledged attic room, then the angle of inclination is calculated as follows:

For example, the end of the roof (the width of the pediment) is 6 meters. This figure is divided in half (6:2=3). The standard roof height at the ridge is always 1.8 meters.

Sin A=a/b=3/1.8=1.67

Using the Bradis table, an approximate value is found for the angle of inclination of the roof with a value of Sin A = 1.67 - this value is in the range of 58-59 degrees. You can stop at the maximum value of 60 degrees, which will become our desired angle of inclination of the 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 roof slopes there are low slope(sloping), average inclination And roofs with steep(highly inclined) stingrays.

Low slope roof that roof, the installation of which is carried out based on the smallest recommended angle of inclination of the slopes. So, each roofing has its own recommended minimum slope.

What does the slope of the roof depend on?

• From the ability of the roof to protect the structure from external factors and influences.
• From the wind- the greater the roof slope, the more value incident wind loads. With steep slopes, wind resistance decreases and windage increases. In regions and places with strong winds, it is recommended to use a minimum roof slope to reduce the load on bearing structures roofs.
• From roofing covering (material) - For each roofing material there is a minimum angle of inclination at which this material can be used.
• From architectural ideas, solutions, local traditions- so in different regions preference is given for one or another roof structure.
• From precipitation: snow loads and rainfall in the region. On roofs with a large slope there will be no accumulation of water. huge quantities snow, dirt and leaves.

What is the roof pitch angle measured in?

The designation of the roof slope on the drawings can be either in degrees or as a percentage. The roof slope is indicated by the Latin letter i.

In SNiP II-26-76, given value indicated as a percentage (%). IN this moment There are no strict rules for indicating the size of the roof slope.

The unit of measurement for roof slope is degrees or percentages (%). Their ratios are 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 an online converter:

Roof slope 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 the pendulum is attached. When the staff is in a horizontal position, the scale shows zero degrees. To measure the slope of the roof slope, the inclinometer rod is held perpendicular to the ridge, that is, at vertical level. On the inclinometer scale, the pendulum indicates the slope of a given roof slope in degrees. This method of measuring slope has become less relevant, since now various geodetic instruments have appeared for measuring slopes, as well as drip and electronic levels with inclinometers.

Mathematical calculation of slope

• Vertical height (H) from the top point of the slope (usually the ridge) to the level of the bottom (eaves)
• Laying ( L ) - horizontal distance from the bottom point of the slope to the top

Using mathematical calculation, the roof slope is found as follows:

The slope angle i is equal to the ratio of the roof height H to the foundation L

i = Н : L

In order to express the value of the slope as a percentage, this ratio is multiplied by 100. Next, to find out the value of the slope in degrees, we translate using the table of ratios located above.

To make it clearer, let's look at an example:

Let it be:

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 given value according to the table in degrees and we get - 24°.

Minimum slope for roofing materials (coatings)