Roof slope: why is this parameter so important and how to calculate it correctly. Calculation of the minimum and optimal roof slope angle in percentages and degrees depending on the type of roof and roofing material Roof angle 20 degrees

Despite the fact that erecting a roof is the last stage of construction of any structure, the design and calculation of roof parameters is included in a number of basic design requirements that are calculated at the starting stage. Most often, the roof angle is chosen not only based on aesthetic considerations, but also strictly taking into account practical and functionality buildings, because the roof protects any home from bad weather.

Types of roofs

Before you deal with the issue of design and setting the required angle of inclination of the roof, you need to accurately determine with roof shape. Depending on the arrangement of the roof, several main types of structures can be distinguished:

1. A pitched roof is characterized by the presence of an inclined plane, which is located on the walls different heights. A device of such a profile is possible when using any roofing material .
2. A gable roof is considered the most reliable and easiest to install. This design has two inclined planes. The range of materials used in manufacturing is quite diverse.
3. The hipped shape of the roof is due to the presence of several isosceles triangles, the vertices of which close at one point. The disadvantage of this form can be called the need to create complex rafter system, which is compensated by a small amount of consumables.
4. The vaulted ceiling is made of stone or brick. IN individual construction It is rarely used because it is very heavy.
5. The hip roof represents very complex design, which has four slopes (two trapezoidal and two triangular shape), with cut off tops.

A pitched roof is considered if the minimum roof slope is ten degrees.

There are two main types of roofing:

1. Operable roofing is used when there is a need to create additional rooms in the space between the ceiling and the roof itself.
2. An unused roof is an option where there is no space between the upper floor and the roof or the use of this area for technical purposes. Flat roofs belong to this type of surface. They have a roof slope of 2-7 degrees, while the distance between the ceiling and the roof is no more than one and a half meters.

The construction of such roofs is profitable because it requires minimum costs for work and materials. High reliability ensures frequent use flat roof.

Pitched roofs make it possible to use free space for household needs (attic, attic). At good insulation you can arrange living quarters.

Factors affecting roof slope

When building a roof, it is necessary to take into account some factors that can have a significant impact on its further safe operation. These factors include:

1. Natural factors are fundamental parameters for calculating the roof slope angle, as they take into account the climate of the area where the building will be located. Wind conditions have a significant impact on both the rafter system and the entire structure as a whole.
2. Technical factors taken into account performance characteristics roofing material used in the construction of the protective surface.

Wind load

Due to the high windage roofing, special attention should be paid to creating an optimal roof slope. Roofs with a greater angle of inclination are more susceptible to the damaging effects of wind. Therefore, taking into account the wind conditions in a certain area, you can calculate the required slope coating surface.

It is better to make a flatter roof and a reinforced rafter system. Although this construction option will be more expensive, your house will be reliably protected from the wind. However, it is necessary to take into account not only the strength of the wind, but also its direction. It is better for metal tiles if the wind is directed towards the plane of the sheets, since when directed towards the end of the sheet there is a high probability of its tearing off. Therefore, it is necessary to pay special attention to the location of the entire structure in order to avoid aerodynamic lift, which tends to tear the roof covering away from the building wall.

The value of wind and snow load can be found out from a map compiled from long-term observations for the entire territory Russian Federation. It is in accordance with such maps that it is determined location of all buildings.

Snow load

It is clear that on the vast territory of Russia there are many different zones where the influence of falling snow significantly affects the entire surface of the roof of a building. Therefore, the main task of correctly calculating the snow load is to determine optimal angle roof slope. The steeper the slope, the less snow can linger on its surface, which simplifies the rafter structure.

The angle of inclination must be calculated taking into account correction factors:

• a tilt angle of less than 25 degrees corresponds to a coefficient of one;
• at an angle from 25 to 60 degrees - coefficient 0.7;
• on roofs with a slope of more than 60 degrees, snow loads are not taken into account.

It is easy to notice that the value changes only with a slope of 25-60 degrees. So, to determine the actual snow load on the surface, you need to multiply the value determined from the map by a coefficient. But this is only part of the calculation.

Influence of roofing material on slope

When constructing a roof, various coatings are used. Of course, we have not yet come up with the ideal material that would suit all regions.

There are basic coatings that are most often used in construction:

1. Slate. This material is considered the easiest to install, reliable to use and cheap to purchase. Has excellent moisture resistance and frost resistance, as well as high performance fire safety. Modern manufacturers We were able to improve the appearance of the products (color, shape). On pitched structures, the minimum slope is six degrees, but it should be taken into account that the heaviness of the material requires the installation of a reinforced rafter system.
2. Roof tiles. Recently, the use of this material has gained particular popularity. There are a huge number of varieties of tiles. Basic positive feature The durability of the coating and the ease of repair work are considered. Minimum tilt angle 10 degrees.
3. Metal profile. Lightweight and durable material made from galvanized steel sheets. It is an environmentally friendly coating that is resistant to rust. Manufacturers currently offer wide choice material on color scheme, size and direction of waves. This coverage is guaranteed for up to 75 years. At small slope angles, overlapping sheets in two waves is required. The pitch of the sheathing must be increased with increasing slope. For flat roofs, it is necessary to make a continuous sheathing, since the sheet may bend when loaded with snow.
4. Roof panels. The production of panels is carried out directly at the enterprise, and they represent almost finished roof. They contain several layers, thermal insulation, vapor insulation and the slab itself. Installation is very simple. Fastening is done with a special tape. The material is good, comfortable, but quite expensive.
5. Bitumen-based materials (roofing felt). This type of coating is most often used in construction. flat designs. For good protection against moisture, an increase in the number of layers is required.

When used on flat roofs, metal tiles or metal profiles are recommended to be treated with frost-resistant and moisture-resistant sealants. The size of the overlaps of such materials depends on the angle of inclination of the roof. This also applies to slate surfaces.

Thus, the angle of inclination of the roof is a very important indicator, on which the time of its trouble-free operation completely depends. The main thing is to choose the right one the desired design and correctly calculate the roof slope. And of course, special attention must be paid to the choice of roofing material.

The operating comfort and reliability of the building mainly depend on how well and competently the roof construction is done, including how correct the slope of the roof is. This will be discussed further.

The slope of the roof of the house mainly depends on the design of the facade and roof of the building, and the material chosen for the covering is also an important feature. The slope is taken into account depending on climatic conditions the region itself in which the new building is being built. For example, in areas where there is heavy rainfall and very heavy snowfalls in winter, choose a slope slope of 45 to 60 degrees. This angle of inclination is specially designed, as it reduces the load, especially in winter periods, on the roofing system, since snow simply will not accumulate on the roof, but will slide down due to its own weight.

And if they are designing a roof for a region characterized by strong and constant winds, then choose the minimum one, since this reduces the so-called “windage” of the roofing. Basically, the angle is chosen from 9 to 20 degrees. Therefore, the most universal solution- this is a value chosen between the two ranges indicated above, i.e. it is best to make an angle of 20-45 degrees. A slope of 20 to 45 degrees has another advantage - it is the ability to use most roofing materials purchased on modern markets.

Types of house roofs

Types of roofs: a – flat gable, b – steep gable, c – hip hipped, d – single-pitched (in the shape of a desk), e – broken (mansard) gable, f – hipped hipped, g, h, i – half-hipped (attic) hipped.

The most common for utility or utility buildings is the shed roof form of the house, which does not offer an original design, but at the same time attracts with its ease of construction and its low cost. The structure of such a roof consists of walls and roofing material laid on them.

Tilt in in this case should be from 9 to 25 degrees, since most often these are the roofs that are subsequently covered with corrugated sheeting. This rather small angle of inclination is formed due to the absence of an attic area.

Another fairly common type is gable roof Houses. Its design consists of two slopes (two planes) connected by a ridge (one line). The walls are the ends of the building and are called gables. They often include doors that allow the attic to be used as additional room, besides, these doors act as vents (ventilation holes). Making such roofs is easier than all others.

Modern designers and just builders often make hip roofs. They allow you to create a unique design of the facade and broken-shaped roof. In such structures, the slope angle can be absolutely anything, depending on the imagination and taste of the person who designs the roof structure. There are practically no restrictions on the use of roofing material in the construction of such roofs. The complex design is compensated by the spectacular appearance of the roof of the house, and the more complex it will be general plan, especially original design a hip roof may work.

A more complex type of hip roof is a broken-shaped attic roof, the purpose of which is to use the attic space in a living space, while insulation and vapor barrier are required.

Due to the rather high angles of inclination and broken-shaped slopes, a space is formed, of which the entire attic floor. In addition, it would be appropriate to make so-called “dormer” windows, which will serve as an additional decoration of the facade. And you just need to perform insolation (lighting the room with sunlight).

You should also familiarize yourself with the data on the smallest angle for various materials:

1. 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.
2. For roll materials minimum angle the slope 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.
3. A 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.
4. For roofs covered with metal tiles, the minimum angle is 14 degrees.
5. For roofs covered with ondulin, the minimum angle is 6 degrees.
6. For soft tiles, a small angle is considered to be 11 degrees, and regardless of the chosen angle, there is a prerequisite - installation of a continuous sheathing.
7. Membrane coatings have a minimum angle of 2 degrees.

Example of roof slope calculation

The angle of inclination of the roof is calculated, as we have already said, taking into account the climate of the area and the selected covering material. The height of the ridge and the value of the rise of the rafters are determined with a square or the width of the span is calculated, divided in half and multiplied by the corresponding coefficient from the table.

For example, if the width of the house is 10 m and equal to 25 degrees, then the height to which the rafters should rise is calculated by multiplying 5 m (half the width of the house) by the coefficient from the table (0.47) and we get 2.35. It is to a height of 2.35 that the rafters should rise.

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 significance 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 the snow cover.

If a building is being erected where weather with strong winds prevails, it is advisable to choose a minimum roof slope angle 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 an area with warm climate, Where sunny days much more than cloudy ones will be more acceptable flat roofs: 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 of a 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 fact, such a building has walls of different heights with a ceiling 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 line of the ridge. Other (end) planes are vertical and are called pediments. They may have doors to access a 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. Dignity hip roofs– in the absence of restrictions on the use of roofing material.

Option hip design– attic: the attic space is used as a living space, 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 it technical specifications: 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, the strength characteristics should be taken into account roofing structure: the safety margin should be enough not only to withstand own weight and the mass of roofing material, but also on 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 is installed or with a small pitch (350-450 mm). 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 atmospheric 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 lean-to 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. It's practically perfect 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 is equal to half of the horizontal segment, designated 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 chooses the optimal angle of inclination correctly. 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

Usable area attic room 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 suspended systems are 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.

Depends on the angle of the roof usable 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 drains 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.

The roof of the building is the most different shapes. Moreover, the slope at which the roof is made mainly depends not on appearance, but on practicality and some requirements. Since the sharpness or flatness determines how strong the roof will be and how correctly it will perform its functions. Based on all this, the slope is calculated, taking into account all the important points.

Builders, as a rule, measure this value (the slope angle of the slope relative to the horizon) in degrees or percentages. In order to obtain the most accurate data, they use measuring instruments, used in geodesy. Let me explain, zero degrees means the roof is completely flat, and if the angle is higher, the roof is acute. Corner pitched roof often varies from eleven degrees to forty-five. During construction, it is necessary to make calculations about how steep the slope should be. For this purpose, you must first take into account such points.

It is worth considering such a point as the presence or absence of strong wind where you live. If it is present, then choosing a pointed roof is not advisable. Indeed, due to the fact that a roof with a sharp slope has a high windage, a gust of wind has a destructive effect on it. In this case, it is better to opt for a flatter type of roof (it is better that the slope of the slope is as small as possible, for your own safety), and use reliable, reinforced rafters. Of course, construction will be more expensive, but the roof will be more protected from factors such as wind. Although during the construction of the roof of a house it is necessary to take into account not only the power of the wind, but also where it blows. Thus, for a metal tile roof it will be better if the wind is directed directly into the plane of the sheets. And if the wind is directed towards the ends, then there is a possibility that the roof sheets will tear off and bend. Therefore, you need to take into account the main direction of the wind in order to rotate the roof slope in accordance with this.

Precipitation and snow loads

If in winter there is a lot of snow in your area, then the roof should be made with a slope of at least forty-five degrees (more is acceptable, as long as it is not less). This is done so that the snow masses slide down, otherwise snow deposits will form on the roof, which can deform the coating. And if the roof is made at the required angle (at least forty-five degrees), then you don’t have to worry about reinforcing the rafters, since this is not necessary. As, in principle, about a system that will retain snow masses. But the wind load for such a roof is higher. For this reason, the final decision on the choice of roofing is made taking into account all weather conditions.

It is worth paying attention to the fact that in addition to snow masses, rain, hail, and sun will test your roof's strength from time to time. If you live in a place where the sun predominates and there is little precipitation throughout the year, then you can opt for a flat roof with the least slope.

An important point: although the roof is called flat, it still needs a slope. So, for this type of roof, a slope of one degree or 1.7 percent is required.

Roofing material

The material used for roofing can be either smooth or rough. From a rough surface, liquid will drain worse and will also linger on it (snow masses too). Liquid will drain from a smooth surface in no time. There are others construction parameters, which should be taken into account when choosing a roof slope.

Minimum permissible roof slope for various materials

Metal tiles

The minimum slope angle of roof slopes with a metal tile covering should be fifteen degrees (there are manufacturers of this type of coating that allow an angle of fourteen degrees). For slight slopes, some manufacturers advise impregnating each joint of the sheets with a sealant and moisture-resistant compound that is not afraid of frost. But in practice, it was noticed that the snow masses cake most of all on a roof with a metal tile covering, the slope of which is from twenty to thirty-five degrees. An excessively minimal slope is not recommended, since the liquid will not have time to leave the roof, thus putting pressure on it and leaking under the joints during significant heavy rains. This situation You can adjust it a little by choosing tiles with higher waves.

Profiled sheet (corrugated sheet)

This type of roofing requires a slope of at least twelve degrees, which is less than for metal tiles. Minor slope angles require a two-wave overlap, and angles of fifteen degrees or more require an overlap of twenty centimeters. The width of the frame becomes higher with increasing inclination. For a practical flat roof, a solid frame is used, because when significant volumes of snow accumulate, the roof may sag.

Flexible tiles (soft roofing)

The frame for this type of covering is a solid base made of sheets of plywood or OSB. Minimum slope slopes for flexible tiles should be at least eleven degrees.

Bitumen-based materials

For this soft coating, just two degrees is enough. For a very slight slope, it is necessary to increase the number of layers of the roof (because good water resistance is of great importance for a flat surface). If you are going to use only one or two layers, then you need to tilt it at least fifteen degrees.

Euroslate (Ondulin)

Ondulin requires a slope of at least eleven degrees. However, when using Euro slate on a roof with a slight slope, there is one important condition: it is necessary to use a solid type frame.

Clay tiles and asbestos-cement slate

This type of material requires a slope of twenty-two degrees. In addition, it is necessary to take a closer look at the calculation of the rafter system, because the loads from the material, which has considerable weight, will be significant. And if you also take into account the accumulation of snow masses or a strong squall, then in general it turns out that it is necessary to increase the requirements for roof support. It is also worth considering that if you reduce the slope, this will lead to an increased load on the support.

How to calculate the roof slope: a few recommendations

Let's discuss the correctness of calculating the angle of the roof. First, note that slope can be measured in both degrees and percentages. Sometimes inexperienced builders can confuse them with each other, which leads to mistakes in calculations. And these values ​​are completely unequal to each other. Although, if you are careful and use special tables, you can easily convert the values.

The relationship between degrees and percentages in roof slope

Degrees, 0	Percentage, %	Degrees, 0	Percentage, %	Degrees, 0	Percentage, %
1	1,7	16	28,7	31	60,0
2	3,5	17	30,5	32	62,4
3	5,2	18	32,5	33	64,9
4	7,0	19	34,4	34	67,4
5	8,7	20	36,4	35	70,0
6	10,5	21	38,4	36	72,6
7	12,3	22	40,4	37	75,4
8	14,1	23	42,4	38	78,9
9	15,8	24	44,5	39	80,9
10	17,6	25	46,6	40	83,9
11	19,3	26	48,7	41	86,0
12	21,1	27	50,9	42	90,0
13	23,0	28	53,1	43	93,0
14	24,9	29	55,4	44	96,5
15	26,8	30	57,7	45	100

1. The slope, which is measured in degrees, is the actual angle between the arch and the support. It is calculated as follows: divide the height of the ridge by half the width of the roof. When the roof has a broken shape, we take part of the width of the building that is located under this section of the roof. For example, near the building simple roof, the width of which is ten meters. The height of the ridge is two meters. We carry out calculations. We divide two by five, the result is 0.4. It is converted into percentages without any problems: we multiply the resulting number by one hundred. As a result, we get forty percent.
2. There are even more easy way. We go to the World Wide Web and find a calculator in real time to calculate the slope of the roof (there are many similar ones on the Internet). We substitute the required values, which are the width of the house and the height of the ridge. Here you can easily calculate the length of the support in the blink of an eye.
3. The next method is more for those who rely on their eyes and hands. You simply need to take and take measurements of the inclination, using an inclinometer, which is also called an inclinometer. Nowadays, there are a huge number of variations of this instrument - analog and even digital.
4. Considering that the width of the building cannot be changed, the slope of the roof plane can be changed by changing the ridge. But this can only be done under the conditions that the walls and foundation of the building are reliable. Once the builder has selected the appropriate slope, he can find the height of the ridge needed. For this purpose, you can use special tables where the coefficients are indicated; you need to multiply half the width of the overlap by them (the slope is indicated).
5. In fact, the height of the ridge can be found without problems. It is necessary to mark the two outer walls of the building (our ramp will run along them). The cord is rubbed with chalk and pulled as tight as possible between these marks. We find the center of the cord, and here we install the bar. We place the plank strictly perpendicular to the plane of the arch (it is better to clarify this using an inclinometer).

By changing the position of the rope relative to the bar, we try to achieve the required inclination. Why do we sometimes measure the size of the angle from the wall. When the required result is achieved, we make a mark on the bar. We saw off this part and make a sample for the ridge supports. When there is no need for supports, then at the ends of the roof we calculate the height of the joint of a pair of rafters, for which we fasten the slats with a stretched rope.

Video

The roof occupies an important place in the design of any type of building, since it is responsible for providing basic comfort conditions and does not provide external factors damage the decoration of the house.

Of course, quality shelter requires many factors to be considered during the design process. One of the main positions in this context is the calculation of the roof slope angle.

Why is it so important and what do you need to know so that the calculation is correct and subsequently you won’t have to redo the roof partially, or even completely? We'll talk about this in this article.

Calculation of roof slope it is best to produce using a special online calculator , which is located below.

The angle of the roof slope is the geometric formation of the intersection of two planes. They mean a horizontal plane and a similar slope surface.

So, why measure the roof angle:

1. Measuring the construction azimuth, first of all, allows you to “estimate” the feasibility of installing a roof, taking into account the selected roofing material, climatic features, the purpose of the attic and the design of the canopy itself.
2. In addition, after making calculations, you can not only rationalize upcoming financial expenses, but also ensure the correctness and reliability of the design, which will not entail losses due to leaks, collapses, cracks in rafters and other incidents.
3. The roof slope is taken depending on two parameters - the first concerns weather conditions and precipitation volumes, and the second is characterized by the specifics of the type of roof. Accordingly, when it comes to northern and snowy areas, then the future roof will have to deal with significant loads. Residents of mountainous regions are familiar with such difficulties firsthand.
4. Some roofs have to withstand snow for 6-8 months a year. In the current conditions, the owners of snow-covered houses have made life much easier by a steeper degree of inclination. In turn, such construction bearings allow the hip to rationally deal with precipitation and its consequences in the form of melt water. Also, with this approach, the size of the usable area increases.

PLEASE NOTE!

When the slope is set at 45 degrees and above, the calculation of the snow load is no longer taken into account, since such a roof is “self-cleaning”.

Of course, not everything is so good with a sharp rhumb, because as the slope increases, the need for additional volumes of both roofing materials and structural elements increases proportionally. The issue of increasing the durability of load-bearing parts also becomes relevant.

No less important when calculating the slope is the specificity of the material that will complete the structure of the canopy with outside. It's no secret that each type of roof top element differs in performance properties and cost.

At the same time, nuances can be provided that are characteristic exclusively of this type of top layer of the roof. For example, it may be necessary to lay additional layers, or higher costs will be required for thermal and waterproofing.

The slope angle depends on the wind rose

Perhaps the third most important factor on which the calculated slope depends is establishing exploited or non-exploited status. The non-exploitable surface provides for the exclusion of space at the junction of the ceiling and the external protective structure.

Visually, the interpretation of the concept looks much simpler, since when you see flat hips or there is a slight slope (in the range of 2-7%), it immediately becomes clear why it received such a name. An usable attic indicates the presence of attic space.

Calculation of roof slope angle: calculator

Field designations in the calculator

Specify roofing material:

Select a material from the list -- Slate (corrugated asbestos cement sheets): Medium profile (11 kg/m2) Slate (corrugated asbestos cement sheets): Reinforced profile (13 kg/m2) Corrugated cellulose-bitumen sheets (6 kg/m2) Bitumen (soft , flexible) tiles (15 kg/m2) Galvanized sheet metal (6.5 kg/m2) Sheet steel (8 kg/m2) Ceramic tiles (50 kg/m2) Cement-sand tiles(70 kg/m2) Metal tiles, corrugated sheets (5 kg/m2) Keramoplast (5.5 kg/m2) Seam roofing (6 kg/m2) Polymer-sand tiles (25 kg/m2) Ondulin (Euro slate) (4 kg/m2) m2) Composite tiles (7 kg/m2) Natural slate (40 kg/m2) Specify the weight of 1 square meter of covering (? kg/m2)

kg/m 2

Enter the roof parameters (photo above):

Base width A (cm)

Base length D (cm)

Lifting height B (cm)

Length of side overhangs C (cm)

Front and rear overhang length E (cm)

Rafters:

Rafter pitch (cm)

Type of wood for rafters (cm)

Working area of ​​the side rafter (optional) (cm)

Lathing calculation:

Sheathing board width (cm)

Sheathing board thickness (cm)

Distance between sheathing boards
F (cm)

Calculation of snow load (pictured below):

Select your region

1 (80/56 kg/m2) 2 (120/84 kg/m2) 3 (180/126 kg/m2) 4 (240/168 kg/m2) 5 (320/224 kg/m2) 6 ​​(400/280 kg/m2) 7 (480/336 kg/m2) 8 (560/392 kg/m2)

Wind load calculation:

Ia I II III IV V VI VII

Height to the ridge of the building

5 m from 5 m to 10 m from 10 m

Terrain type

Open area Closed area Urban areas

Calculation results

Roof angle: 0 degrees.

The angle of inclination is suitable for this material.

It is advisable to increase the angle of inclination for this material!

It is advisable to reduce the angle of inclination for this material!

Roof surface area: 0 m2.

Approximate weight roofing material: 0 kg.

Number of rolls of insulating material with 10% overlap (1x15 m): 0 rolls.

Rafters:

Load on the rafter system: 0 kg/m2.

Rafter length: 0 cm

Number of rafters: 0 pcs.

Lathing:

Number of rows of sheathing (for the entire roof): 0 rows.

Uniform distance between sheathing boards: 0 cm

Number of sheathing boards with a standard length of 6 meters: 0 pcs.

Volume of sheathing boards: 0 m3.

Approximate weight of sheathing boards: 0 kg.

Snow load region

Decoding calculator fields

Roof slope in percentage and degrees

How to determine the angle of a roof in degrees? Oblique angle, like any similar figure, according to geometric canons, is measured in degrees.

But in many documents, including SNiPs, this value is displayed as a percentage, so there are no strict requirements and justifications to be guided by only one unit of measurement.

The main thing in this situation is to know the proportions for the relationship if you suddenly need to convert degrees to percentages and vice versa, for example, for convenience during computational operations.

In general, the degree-to-percentage conversion factor ranges from 1.7 (for 1 degree) to 2 (for 45 degrees). In cases where indicators that are not expressed as a whole percentage are fundamentally important, ppm - hundredths of a percent - are used in digital display.

If you trust the theory, then the inclinations can reach 60 and even 70 degrees, but in practice this will not look entirely appropriate. Yes and by appearance the impression is “so-so”, unless your house is located somewhere in the Alps and you need to build a roof that is constantly exposed to snow loads.

Converting degrees to percentages

Specifics of flat and pitched roofs

Flat floors are not represented by a purely horizontal surface, no matter how misleading its name may be. The construction azimuth in this situation also has a slope, although not significant - its the minimum value should be 3 degrees.

PLEASE NOTE!

There is one nuance that must be taken into account when designing a flat surface. A prerequisite is the installation of drainage funnels, the walls of which will tilt by 1.5 degrees.

As for the optimal values ​​for flat coatings, then The slope of a flat roof fluctuates around 5-7 degrees. This is due to the fact that roofs with an angle greater than 10º can hardly be called flat. In turn, 12-15 degrees in most situations is already interpreted as the minimum threshold for sloped surfaces. The optimal values ​​are wide enough.

Optimal roof angle for snow removal is 40-50 degrees.

Flat roof slope

For example, for lean-to sheds a range of 20 to 30 degrees is assumed, and in the case of gables this figure rises to 45º. It’s just that this volumetric interval largely indicates the individual characteristics of the roof type and climatic features.

CAREFULLY!

With a small azimuth, the joints are treated with frost and waterproof sealant without fail. If the indicator is 15 degrees or higher, then the corrugated sheeting should be laid with an overlap of 200 mm, and if the roof slope is less than 15º, the overlap increases by two “waves”.

Minimum roof slope

Roofing material, which is one of the main elements of the structure of the upper plane, also provides certain slope recommendations depending on its type.

• In the case of corrugated sheets, set the angle at 12 degrees, for metal tiles this indicator should be increase to 15º.
• Ondulin or soft tiles in common language you can lay on a slope of 11 degrees. But in this case there is also one nuance, which is in a continuous sheathing.
• When covering ceramic tiles, tilt must be at least 22º. It is also worth considering that the rafter system is subject to heavy loads if the slope is slightly inclined. To avoid overloads, this factor should be taken into account during design.
• The most common type of surface covering is slate. When laying asbestos-cement corrugated sheets, the roof slope indicator should not exceed 28%. The same requirements apply to steel planes.
• Minimum roof slope from sandwich panels according to the standards is 5 degrees, if windows are planned in panels, then the slope increases to 7 degrees.

Dependence of slope on the choice of roofing covering

How to determine the roof pitch yourself

To measure the slope angle, you can use a miracle device that can relieve you of all the computational burden. The name of the device speaks for itself - inclinometer (inclinometer).

In general, you can turn to a mechanical inclinometer for help - a budget option, but additional hassle is not excluded, especially if you are using such a device for the first time.

However, we will tell you the specifics of this device - perhaps, thanks to it, our reader will very soon be familiar with this element.

• A standard inclinometer without electronic bells and whistles is presented in the form of a rod with an attached frame. At the junction of the slats there is an axis on which the pendulum is fixed. Its unique set includes 2 rings, a weight, a plate and a pointer. The device is complemented by a scale with divisions, which is located in the inner part of the cutout. If the staff is placed horizontally, the pointer will coincide with the zero division of the scale.
• Now let's move on to the main process for which the device is intended. Align the protractor rod perpendicular to the ridge. After this, the required value in degrees will be displayed on the pendulum pointer.
• Option based on carrying out your own calculation task to measure the slope using mathematical calculations, unattractive. In any case, we will try to clearly explain how you can do this yourself. First of all, you need to find out the length of the hypotenuse and legs. When it comes to measuring the slope of the roof, the straight line of the slope is the display of the hypotenuse.
• Then we calculate the length of the opposite and adjacent legs. The first of them is presented in the form of a distance separating the ceiling and the ridge, and the size of the second should be taken as the distance between the middle of the ceiling and the eaves overhang of a certain slope.
• Now, having already received two values, finding the third by applying trigonometry is not difficult. As a result, knowing the sine, cosine or tangent (depending on the sizes of the components) we calculate using an engineering calculator digital value slope as a percentage.
• Still have questions? Watch the video lesson below or use our online calculator.

Ratio of ridge height to span

In general, the algorithm for conducting settlement operations can be divided into four steps. First, we take into account external natural factors influencing the future surface layer, compare our construction plans with price tags for the necessary resources in online stores, decide on the type of material for the roofing and do not stop getting information from specialized sites and, if possible, consult with professionals.

Regarding loads, it is better not to bother with minimal slopes, as this can end badly for a “fresh” roof. But if the roof is flat and there is nowhere to go, then do not neglect fortifying redoubts.

When calculating the cost, also do not ignore such concepts as the weight of the house structure and, again, the load from precipitation - this will help you find not only the right, but also an economically pleasant solution for your wallet.

Roof calculation

If the inclination is up to 10 degrees, then suitable option there will be surfaces made of gravel, up to 20º - corrugated sheets and slate. Steel and copper sheets are advisable even in very “steep” cases, when the upper point reaches 50-60 degrees.

Actually, that’s all the information you need to independently calculate the roof slope angle.

Useful video