Minimum and maximum slope of flat roofs on snip. Calculation of the minimum and optimal angle of inclination of the roof in percent and degrees depending on the type of roof and roofing material Roof slope norm

Roofing is one of the important stages of construction. The roof protects the home and performs an aesthetic function, completing the design of the building. The choice of the right material is not the only significant nuance. It is also necessary to correctly calculate the roof slope. This article will tell you how to do this.

Peculiarities

In modern projects of country houses, a large number of requirements are taken into account. Performers are forced not only to comply with the norms, but also to implement the wishes and whims of customers. However, in the foreground there are still regulatory requirements, because the roof, first of all, must be reliable. Therefore, architectural delights often fade into the background.

The roof covering must fulfill its intended purpose - to protect from moisture. In some cases, thermal and sound insulation is required. This is sometimes necessary to increase the functionality of the premises under the roof. Therefore, designing a roof cannot be called a simple matter. This work requires extreme responsibility, especially if the customer insists on a complex configuration. In different situations, professionals use different techniques. Calculations are performed using the appropriate software.

The theory of calculations can be of interest to the owner of the house. For example, such knowledge makes it possible to check whether the correct technique was applied by professionals. They also help to competently present their author's ideas. In addition, the calculated parameters make it possible to determine the required amount of building materials for both the rafter system and the roofing.

The peculiarities of the calculations are that professionals use different quantities for measurements. For example, not everyone measures the slope angle in degrees. In the everyday life of some masters, there are concepts such as percentage or relative aspect ratio. You also need to know what is taken as the angle of inclination of the roof.

The angle of inclination of the roof is formed by the intersection of two parameters:

• one horizontal plane;
• one plane of the roof slope.

This parameter is measured from the top edge to the base of the rafter system. In the calculations, only acute angles are taken into account, since obtuse slopes do not exist by definition. Steep slopes are rare. As a rule, they are used for decorative purposes (for example, when they build turrets in the Gothic style).

Attic roofs can be steep. In this case, the lower rafters are positioned at a very large angle. On ordinary roofs, slopes up to 45 degrees are mounted.

For a better idea of ​​how it should look, you can take a protractor and look at the divisions with degrees.

The value of the inclined angle is calculated as the ratio of the parameters of the ridge to half the width of the structure, multiplied by 100. Most professional builders use the so-called tabular charts. Depending on the indicators, it is customary to subdivide roofs by type.

Kinds

Experts identify several main types of roofs.

• Shed roof. In this case, the roof looks like a flat plane. It has distinctive height parameters.

• Gable roof. It is a reliable, easy-to-install option. The roof includes two slopes connected at right angles.

• Hip roof. It is supplied with four slopes, two of which are triangles, and two more are trapezoids. The top of such a roof looks cut off. Despite the complexity of the structure, such roofs are very economical in terms of material consumption.

• Vaulted roof type. It is rare as it involves a limited selection of materials. Such options are erected only from brick or stone. The rarity of the choice in favor of such roofs is also due to their heaviness. In small private construction, this type is practically not used.

• Multi-gable roof type. It is complex in configuration, but very beautiful. Such a roof is difficult to install due to the many abutments and lintels.

Also, experts identify types of roofs that can be subsequently operated., and options that are not exploitable. If professionals classify the roof as an unexploited type, this means that there is practically no space between the roof itself and the upper floor. This territory can be used, but only as a technical one. For example, this is a low-slope single-pitched roof.

Shed roofs are the most profitable for construction. They require a minimum of material costs, but the work can be done independently. If the roof has a slight slope, then a resting place can be realized on its surface without the construction of a complex attic.

Roof space can be used if the roof type is pitched. The attic area can be used for household needs. Also, due to it, you can expand the living space.

The choice of this or that type of roof is associated with many nuances. One of the main factors is the climatic factor.

Climate influence

For example, a huge load on a roof structure can be caused by wind. Even a slight increase in the inclined angle increases the wind load. For example, if the angle of inclination of the roof is more than the standard values ​​by 30 degrees, the wind load becomes five times greater. Therefore, even a slight increase in indicators can play a cruel joke with the owner of the house in case of a natural disaster.

Precipitation affects the quality of the roof no less destructively. At the same time, a well-chosen slightly higher slope will avoid the accumulation of snow on the surface. Snow will not melt at all with a roof slope of 30 degrees. And with a slope of 45 degrees, the normative indicators for the snow load on the roof will be observed.

In northern countries (Sweden, Finland, Norway, etc.), it is customary to make very high pitched roofs. Obviously, snow does not linger on high slopes. However, it is generally accepted that some layer of snow on the roof plays the role of additional thermal insulation.

To eliminate the risk of breaking the roofing material, a strong rafter system is performed, because a large weight will affect the entire structure.

It is worth remembering that the larger the slope of the roof, the more funds will have to be spent on construction. Also, the costs are associated with the choice of the roof covering option (not all materials can be laid on high pitched roofs).

For different materials

Before choosing a roofing material, you should carefully consider the technical features of the coating. This will help you make the best decision and choose the most reliable option. There are rules that determine the relationship between the angle of inclination of the roof and the applied roof structure.

Slate or shingles can be installed on roofs with a minimum slope of 22 degrees. On roofs with a smaller slope, moisture will accumulate and seep inside at the joints of the parts. If the roof has slopes with a lower degree, roofing felt and other bituminous materials can be used, which are mounted with a solid sheet.

Profiled sheet manufacturers declare that this material can be laid at a minimum angle of 12 degrees. Moreover, if the slope angle is minimal, then the joints between the sheets must be glued with a sealant.

For metal shingles, the minimum possible slope is 14 degrees. At the same time, there are rules for arranging floors. For example, if the angle is more than 45 degrees, then the installation site of the ridge board changes. The method of mounting the ridge itself is also changing. At small values ​​of the value, an aero roller is attached between the ridge strip and the tile. It prevents snow from penetrating under the roof.

For a roof covered with ondulin, the minimum possible slope is 6 degrees. For soft tiles, the optimum surface slope is 11 degrees. Although a larger bias is acceptable for this material. In this case, the crate must be continuous.

Membrane-type coatings are more versatile. PVC membrane, EPDM membrane, TPO membrane are modern materials suitable for roofs of any shape. The versatility of materials is due to the excellent technical characteristics and long service life.

When choosing a particular coating material, one should take into account not only the features of the slopes, but also the strength values ​​of the roof. Structures must support not only their own weight, but also the mass of the roofing material. In addition, the entire roofing system must successfully withstand external loads.

The slope of the slopes is often associated not only with the choice of materials, but also with the choice of the type of crate. If the angle of the slope has a small value, then a solid crate is mounted. Also, when installing a flat roof, a drainage system is required. There are standard parameters for any roofing option. They should be borne in mind, even if the simplest flat version is chosen.

Guideline values

Arrangement of a flat roof is a simple undertaking. The main thing is to use properly selected high quality material. The slope of the flat roof is also of great importance.

In fact, a flat roof is not completely horizontal. A slope equal to 15 degrees is constructed on such a roof. Slopes must be present, since only in this case will water flow into the drains. If the slope is not done in accordance with the established norms, stagnant water will form on the roof surface.

When choosing certain bases, the type of construction should be taken into account. For example, if the floors are wooden, then the additional weight for the roof is contraindicated.

Today, you can find on sale special boards that are distinguished by high thermal insulation qualities. Such slabs are wedge-shaped. It is enough to lay the material on a flat surface. The result is a bias that corresponds to the normative indicators. The only drawback of the material is the rather high cost.

When using other materials, first you need to make sure that the surface is completely flat. Then beacons are installed on it. The slope must be directed towards the gutters.

When creating a slope, it is worth considering the area of ​​\ u200b \ u200bthe roof. For a garage roof, for example, one slope should be taken into account, which will be directed into the drain funnel. Slope for a standard house of 80 sq. m will be 2-4 slopes. Moreover, all of them should be directed to the drainage system in order to freely deliver water into it.

How to calculate?

If there are usually no difficulties with the arrangement of a flat roof, then engineering calculations are necessary for the installation of a roof with several slopes. The easiest way is to calculate and determine the values ​​in degrees. For example, to equip a roof with a sloped angle of 30 degrees, you can use a mathematical method.

This requires two measurements.

• Vertical Height (H). The value is measured from the top of the inclined plane to the bottom of the rafter system (from the ridge to the eaves).
• Laying (L). This is the horizontal length from the midpoint of the bottom of the ramp to the eaves.

Mathematical calculation is carried out according to the formula. You can calculate the required parameter as follows: I = H: L. For example, the length of the laying is 5 m, and the height is 3 m. In this case, the slope will be 0.6 (when calculating I = 3: 5). This value must be multiplied by 100. It turns out 60 percent.

To convert the value to degrees, you can use a special ratio table. It can be found in specialized textbooks. Sometimes such a table can be found on sale in construction hypermarkets. It is not necessary to translate relative values. With the values ​​from the above example, the tilt angle will be 30 degrees.

Experts do not always use a conversion table in their measurements. The percentage factor can be applied in the same way as the degree factor. In general, professionals use special tools in their calculations. For example, you can measure the area parameter using a special inclinometer.

The tool is a ruler with a staff. One axis contains the familiar scale in centimeters, the other a pendulum. If the bar with divisions is horizontal, then the pendulum will show zero. When measuring the slope, the rail is installed perpendicular to the ridge. In this case, the scale shows the result for a specific value immediately in degrees.

Currently on the market you can find a variety of tools that can measure slopes. Levels can be either drip-type devices or electronic devices. In this regard, the mathematical method of measurement cannot be considered relevant. Modern devices allow for more accurate calculations.

Any house is crowned with a roof - one of the main structures of the building, which protects its interior from rain and snow. One of the main criteria for any roof is the steepness of the slopes. Since a flat roof is prevalent mainly only in multi-storey residential and industrial construction, this issue is especially relevant for owners of private houses and cottages.

The amount of roofing material depends on the value of the slope of the roof, therefore the choice of the angle of inclination and its preliminary calculations should be made before purchasing the roofing material.

Let's consider how to determine the angle of inclination of a pitched roof and its relationship with the design of the entire roof structure.

In this article

What determines the steepness of the roof?

The angle of inclination of the roof directly affects its performance. In construction, there are 4 types of roof structures:

• Steep with a slope of 45-60 °;
• Pitched - 30-45 °;
• Gentle - 10-30 °;
• Flat with a slope of less than 10 °.

The definition of this value depends on a number of factors:

• Wind exposure. The wind exerts the greatest pressure on steep roofs, since they have the greatest windage due to their large surface area. When arranging such a structure, it is important to pay special attention to the strength of the rafter system.

In areas with a high wind load, it is also dangerous to arrange flat and shallow roofs: if the structure is weakly fastened, it can break down. Thus, in areas with strong winds, the recommended roof slope angle is in the range of 25-30 °.

In areas where a significant amount of snow falls during the cold season, a steep roof, on the contrary, has advantages. Snow does not accumulate on it. At a lower angle, the snow will lie on the roof longer, creating an additional load on the rafter system.

It is not necessary to equip a steep roof: a certain amount of snow that lingers on the roof in winter has the useful property of retaining heat. However, it is important to calculate the load that the snow cap will put on the structure in order to prevent it from collapsing.

• Roofing material. Each type of roof has its own restrictions on the angle of inclination of the slopes. If you plan to use a specific roofing material, then it is important at the design stage to correlate the desired roof slope with its technical characteristics.
• Attic size. The angle of the roof directly affects the size of the room below it. The steeper the roof and the higher the ridge, the more spacious the attic and vice versa.... When planning a room under the roof, one should not forget about the risks inevitably associated with a steep structure, and its high cost compared to the construction of flatter roofs. A broken type can come to the rescue in this situation, which allows you to save the maximum volume for arranging the room, saving on the height of the ridge.

Minimum angle of inclination

Such a concept as the minimum angle of inclination of the roof is in relation to the used roofing material. All roofs are provided with technical specifications, which, among other things, clearly indicate the slope limits for use. It is impossible to violate these rules, since in this case the roofing material will not retain its original functions and advantages.

Consider the main roofing and minimum angles for them:

• Piece roofing materials (slate, tiles) are laid on roofs with a slope of 22 °. This indicator is due to the fact that in this case water does not accumulate at the joints of the roofing elements and, accordingly, cannot seep under them;
• When working with roll materials such as roofing felt, it is important to determine in advance the number of layers. If you plan to lay 2 layers, then the roof angle should be at least 15 °, when laying 3 layers, this value can be reduced to 2-5 °;
• The corrugated board is mounted at a slope of 12 °. A lower value will require processing all joints with a sealant;
• The metal tile spreads at a value of 14 °;
• Ondulin - from 6 °;
• Soft shingles can be installed on the roof with a slope of 11 ° if there is a continuous sheathing;
• Membrane roofing materials are the only ones for which the minimum threshold is not indicated. They can be successfully used on flat roofs.

Compliance with the above rules is extremely important, since even a slight violation of them will result in the destruction of the roof and, possibly, damage to the rafter system.

Slope calculation

In addition to the minimum angle, there is such a thing as the optimal tilt angle. With it, the roof is exposed to the minimum possible loads from wind, snow, etc. Let us give examples of such optimal values:

• In areas with frequent precipitation in the form of rain and snow, it is optimal to build a roof with a steepness of 45-60 °, since it quickly gets rid of precipitation, which minimizes the load on the rafter system;
• If the roof is being erected in a windy region, then it will be good to place its angle of inclination in the interval of 9-20 °. It will not play the role of a sail, catching the passing wind, but it will not capsize by its sharp gusts;
• In areas where both wind and snow are regular, refer to averages of 20-45 °. This range can be called universal for pitched structures.

Self-calculation of the angle of the slopes is reduced to a simple geometric process, which is based on a triangle. Its legs are the height of the ridge and half the width of the house, the hypotenuse is one of the slopes. And the angle between the hypotenuse and the leg is the desired steepness value.

The roof angle is in direct relation to the ridge height. There are two options for calculating these values:

• The height of the roof is known... If there is a desire to equip a spacious living room with an acceptable ceiling height under the roof, then the ridge height can be determined in advance. With the known two legs, it is easy to find out the value of the desired angle.

We take the following notation:

• H - ridge height;
• L is the width of half of the house;
• α is the required angle.

We find the tangent of the desired angle by the formula:

tg α = H / L

We learn the value of the angle from the obtained value from the specialized table of tangents.

• Predefined tilt angle... If you want to use a certain roofing material or due to weather conditions in the region, the roof slope can be determined in advance. By its value, you can determine the height of the ridge of the house and check whether it is possible to create a living room under this roof. For the arrangement of the premises, the ridge height must be at least 2.5 m.

Leave the legend from the previous example and substitute the known values ​​into the following equation:

H = L * tg α

Thus, the process of calculating the angle of inclination is much easier and faster than analyzing all populations to determine its optimal value for a particular region and building.

Due to the fact that the pitched roof rests on walls that have different heights, the calculation of the given angle of inclination is carried out simply by lifting one of the walls of the house.

We draw a perpendicular L sd (length of the house wall) along the wall, which originates at the point where the short wall ends and rests on the wall having the maximum length.

If the length of the wall of the house L sd is 10 meters, then in order to obtain an angle of inclination of 45 degrees, the length of the wall L bc should be equal to 14.08 meters.

Conclusion

In roof design, finding the optimal slope angle is essential. This parameter depends on the correct assessment of weather conditions, the choice of roofing material, the desire to create a living space. Its correct definition is the key to a long and successful roof service in all weather conditions.

In order for the roof to serve for a long time and be safe during the entire period of operation, it is necessary to prepare a high-quality project in advance. Also, do not forget about the materials on which you certainly should not save, so that you do not have to overpay, as in one well-known saying. They should not only correspond to the climatic conditions of residence, but also favorably emphasize the architectural features of a private house. After all, the design has not been canceled! But, besides this, you need to take into account the slope of flat roofs. This is the same important stage as the selection and calculation of rafters, insulation.

The operating efficiency of the roof is directly dependent on its slope. And when calculating this parameter, it is necessary to take into account the region of residence, for what exactly the attic is being built and the roofing materials used.

The dignity of flat roofs

Despite the fact that in the construction of private houses, flat roofs are made in isolated cases, they have a number of advantages. And above all - the low cost of work, since less building material is spent in comparison with the construction. Their installation is not as difficult as it might seem. Also, a flat roof is easy to maintain and repair.

If necessary, the roof can act as an additional platform. On it you can arrange a small pool or a children's corner. In addition, a slight slope of flat roofs will allow the installation of any equipment, often air conditioners.

The invaluable advantages of a flat roof make it in demand not only abroad, but also in Russia. This is contrary to the seemingly unattractive design. Currently, the inverted type of roof is gaining popularity. But that's not the point. First, it's worth understanding whether you need to make a bias.

The need for a slope of flat roofs

Many buildings are made with flat roofs. However, it is not quite like that and has a slight bias, since it is spelled out in the requirements of SNiP and is dictated by vital necessity. Indeed, in the absence of a slope on the roof, rain or melt water will certainly begin to accumulate over time.

Even if the roof surface is perfectly flat, and there should be no puddles, reality shows the opposite. Various natural factors are used:

• wind impact;
• solar radiation;
• precipitation;
• temperature drops and others.

As a result of all this, over time, the roof begins to deform. Accordingly, places are formed in which moisture and dirt, blown by the wind, will begin to accumulate. In the presence of at least some slope of flat roofs, this probability is minimal.

What are the consequences?

It would seem that something terrible can happen because of the water? Everyone knows that it is the basis of life for everything on earth. However, this element can easily destroy almost anything in different ways.

And since we are talking about water, which usually accumulates on the roof, then its chemical composition contains a variety of substances. Here they have a detrimental effect on And in winter, the liquid generally turns into a solid state - this is where a powerful crushing force is hidden! And if there is at least some minimal slope of a flat roof, the worst can be avoided.

Many have noticed how vegetation blooms on the roofs - the wind, along with the sun and water, are doing their job. And as you know, the root system of plants is a fairly strong organ that is capable of destroying almost any durable material. Over time, of course, but it doesn't get any easier.

Slope designation

All parameters of a flat roof, including the slope, are regulated by the document SP 17.13330 SNiP II-26-76, which is called the "Code of rules for the roof. The roofs" (translated from the English. The roofs - roofs). This document applies to the design of roofs from almost any material:

• bituminous and rolled;
• slate;
• from tiles;
• profiled, galvanized, steel, copper sheet;
• aluminum, zinc-titanium and other similar structures.

The magnitude of the slope of the slope relative to the horizon, called the slope of the roof, can be designated in different ways. In practice, its value is usually indicated in degrees, which is more convenient.

However, in the documentation, you can find the spelling of the slope of a flat roof as a percentage. Moreover, there are significant differences between these designations. 1 degree equates to 1.7%. 31 degrees will already be equal to 60%. In this regard, it is important to know such ratios so as not to make mistakes when carrying out calculations.

What should you be aware of?

When making a roof slope, it is worthwhile to clearly understand the purpose of this process. Perhaps protection from the harmful effects of external natural factors is needed. In some cases, the slope of the roof depends on the architectural features of the surrounding buildings, and there is no desire to stand out strongly against their background. The material used is also important, since each has its own indicators that are permissible during installation.

But special attention should be paid to. With the maximum slope of a flat roof, the roof will function as a sail, which is not good. On the other hand, precipitation will not accumulate on such a roof. Not a drop of rain or snow will last long on such a surface.

The area of ​​application of the attic also matters. For arranging the attic, it is better not to do steep slopes. And in any case, financial capabilities also make their own adjustments. If it is necessary to erect a roof at an angle of 45 degrees or more, an increase in spending on roofing materials cannot be avoided. Depending on this, the value of the slope angle is selected.

Dependence of the roof material on the degree of slope

In addition to the fact that the device for the slope of a flat roof is directly dependent on the type of material used, this parameter also affects the amount of thermal insulation means. If, for example, the angle of the slope is small, then more thermal insulation will be required, since the moisture from the sloping roof is in no hurry to leave.

Different materials are used to equip the roof. These are slate (asbestos-cement, cellulose-bitumen sheets), metal tiles, roofing felt and other options. Let's consider the most common ones.

Metal tile

This material has considerable weight when compared with other analogs. Therefore, it is important to correctly calculate the roof slope. This is especially critical for areas with frequent and strong winds and hurricanes. In this case, the slope angle should be as low as possible.

If you choose too high a slope of a flat roof, it will swell, which will entail an increase in the load on the supporting structure. As a result, the roof may collapse ahead of time.

As a rule, for such a roof, the optimal slope angle will be 27 degrees. Then the roof will reliably protect the house from moisture. The minimum value is 14 degrees. When using soft material, the slope angle can be reduced to 11 degrees. Only the roof in this case needs additional lathing.

Corrugated board

This material is considered the most popular for roof construction. It is lightweight yet robust enough to meet many of the requirements of property owners. It is not difficult to carry out the installation, and you can cope on your own, with the support of your loved ones.

As for the requirements for the slope of a flat roof, SP 17.13330.2011 (set of rules) allows you to erect a roof with an angle of at least 8 degrees and with a battening step of 40 cm (grade H-60, H-75). However, the material of grades S-8, S-10, S-20 and S-21 allows a slope angle of no more than 15 degrees. In this case, the pitch of the lathing is from 5.0 to 6.5 cm, but sometimes a solid structure is used.

Nevertheless, an indicator of 8 ° is the minimum value that is suitable for the roofs of commercial or industrial buildings. For residential buildings, the minimum threshold is 10 °. But as for the maximum slope indicator, there are no special restrictions. For this material, you can build roofs with even a 70 ° slope, even a large angle.

The optimal value of the slope of the flat roof (the norms will be observed in this case) will be 20 °, which will allow the snow and water to melt in time. Then a very large investment will not be required, and the roof can be laid in two layers. This minimizes the risk of moisture seeping through the fasteners.

Soft roof

Here, too, there are values ​​of the angle of inclination, if we take into account (like roofing material, ondulin) or modern polymer (membrane) products. As a rule, the value of the angle of inclination is in the range of 2-15 °. More accurate indicators depend on the number of layers to be laid.

If a double-layer roofing is required, the angle value is 13-15 °. The slope of the three-layer coating will be narrower - in the range from 3 to 5 °. When using modern membrane material, the threshold is even lower - only 2-5 °.

In other words, the property owner himself chooses the slope of the flat roof; and the rules) are not violated. However, one should take into account the fact that the roof must withstand loads that are not only temporary, but also permanent. The first includes precipitation depending on the season and its weight, gusts of wind. The second is the mass of the roofing material itself, which acts on the supporting structure.

It has a number of its advantages, such as: its installation will take less materials, ease and simplicity of installation and additional useful territory.

For many, the phrase flat roof is in no way associated with a slope. Although this is far from the case. Even the flattest roof has its own slope, even if it is minimal.

At a minimum, this is necessary so that melt water, and water after rain, can safely drain into the installed funnels, which are part of the internal drainage basin, or into the gutter of the external system.

In addition, it is easy and simple to install additional necessary equipment on such a roof. To date, there are several types of flat roofs:

• Operated roof;
• Unexploited roof;
• Traditional roofs;
• Inversion roofs.

The slope that should be on this type of roof is approximately 1-5 degrees, if we neglect this, then water, both rain and melt, will accumulate, which in turn will damage the roof.

In summer, you may not face such a problem, since rainwater dries up under the rays of the sun. In winter and autumn, such water can freeze at night and melt during the day.

Puddles form, which ultimately leads to the fact that moisture gradually penetrates into the insulation... The essence of the mechanism is that moisture penetrates into the layer, which means that inevitable leaks occur.

But this is not the only problem. In addition, puddles on the roof can become dusty, which in due time settles on the bottom. The seeds of various herbs and plants can fall into this puddle and germinate there.

Often on the streets you can find houses with grass or thin trees on their roofs. It is logical that this spoils the roof, and also spoils the aesthetic appearance of the entire building.

To avoid such a nuisance, and thereby extend the life of your roof, it is necessary to carry out the roof slope procedure... Such a complex manipulation is carried out at the time of the construction itself.

The process itself is quite complex, and includes many activities that are different in structure. The purpose of this procedure is for the roof itself to acquire the necessary slope..

But before you start spreading the roof, you need to find out what a flat roof consists of.

Flat roof

In fact, it is a pie of several layers:

• Immediate base, which is reinforced concrete slabs that have a certain wave height;
• which can be made from different materials such as bitumen or roll materials;
• The next layer is which can be made of rock wool or other durable material.

The ingredients of such a pie can be changed if the builder wants to make the entire roof with new building materials. It should be understood that a procedure such as bias, carried out directly at the time of laying the insulation.

It is important that in addition to such basic layers of the roof, there must be water intake funnels or gutters.

The angle of the roof slope is very important, and it depends on many parameters. The first thing to look out for is wind impact... If you live in an area where there are frequent strong winds, then it is worth making a small angle of inclination.

CAREFULLY!

If you make a strong slope of a flat roof, then the wind can tear out the sheets of the roof... It is important to note that the angle of the roof dictates the necessary conditions for the rafter system, as well as for all components of the roof, namely: rafters, sheathing step.

Obviously, the steeper the slope of the roof itself, the faster the outflow of water is.

Percentage slope

Minimum angle and roof slope calculation

The minimum slope angle can be determined based on the materials of the roof itself:

• If the roof is made of, then its minimum slope must be at least 12 degrees(according to SNiP). If the roof is made of, the angle increases to 15 degrees... It is important to understand that cracks in the material and other joints must be treated with a special sealant - frost-resistant / waterproof. If the angle of inclination is 15 degrees, then the sheets of material should overlap about 200mm, if the angle is less, then the overlap should increase;
• The minimum slope angle can be in cases where if the roof of your house is made of artificial materials... These, in turn, include membrane coatings, materials based on bitumen. It is logical that by the value of the slope angle, the number of layers of the roof itself also affects... If, for example, the roof is made in two layers. then an angle of inclination of 15 degrees is quite enough;
• Having covered the roof, you should understand that 11 degrees of inclination is quite enough, but at the same time you need to make a solid type crate.

Such a process as the sloping of a flat roof, made of such materials:

• Extruded polystyrene (TechnoNIKOL);
• Cotton wool, both mineral and glass / basalt based;
• Polyurethane foam;
• Foam concrete;
• Foam glass;
• Various kinds of filling materials.

Each of the materials has its own pros and cons. And before starting work, it is worth correctly calculating the angle of inclination itself... In fact, it is quite easy to carry out this calculation, for this you need to use a goniometer, or else with fairly simple mathematical formulas.

Despite the fact that a flat roof is called a flat roof, it still needs a slope. The minimum slope for a flat roof is 1 degree or 1.7%.

The instructions for the use of bituminous and polymer coatings for slope indicate that the optimal slope angle should be 1.5 degrees. It is permissible to perform a slope of 1-2 degrees.

Everything is very simple here. You need to know the height of the roof and its width... Further, simple trigonometric formulas will help you calculate the right angle (sine, cosine, tangent). And according to the existing table, which was calculated earlier, you can find out the value as a percentage.

There is another way of calculating - the value of the height of the roof, must be divided by half the width, and the result already obtained is multiplied by one hundred, after that, in the table, you can find out the percentage of the future angle of inclination. This option is faster, but both are correct in terms of accuracy.

Minimum slope

Sloping a flat roof with bulk materials

If you decide that the deflection procedure will be carried out using bulk materials, then the first thing worth noting is the scheme according to which such a procedure must be carried out:

1. First of all, on the concrete base itself, it is necessary to lay a layer of glass insulation... This material has not only a long service life (30-35 years), but also has a high level of waterproofing;
2. Farther, it is necessary to pour the main material on it - expanded clay... But at the same time, everyone needs to create the right bias;
3. Necessarily you need to cover a layer of expanded clay, with a special plastic wrap... It is important to note that it must be overlapped;
4. Further, it is necessary to apply the prepared sand-cement screed, doing it smoothly, slowly. Its essence is to level the layer of poured expanded clay;
5. After these events, you can start carry out the formation of the roofing "pie", according to the developed.

Remember that when laying each layer, you need to ensure that the previously prepared angle of inclination is preserved.

ATTENTION!

If you are worried that expanded clay will shift when you start laying a sand-cement screed on top of it, you can fill it with cement milk... But it is worthwhile to understand that because of him, the structure becomes heavier.

If you want to create a minimum angle of inclination, and the roof area is not very large, then a sand-cement mortar will be enough.

Bulk material

Thermal insulation materials

Another good material for roof deflection is thermal insulation materials. Experts say that this is the most affordable option.

Its advantage is that it is light enough and quite cheap, which plays a very important role in the construction site. Mineral wool, the best material. The process diagram is quite simple.

It is necessary to attach the material to the base itself, using self-tapping screws or dowels. Some people prefer to stick such cotton wool on a previously cleaned base with special glue. This process can be performed both during and during the installation of the roof.

Heat insulating material

Foam concrete

A good material that can be used for flat roofing is foam concrete. It should be noted right away that such a procedure must be carried out using special equipment.

A layer of foam concrete is poured onto the base itself, but at the same time the angle of inclination itself is noted, and after make a special screed from foam fiber concrete... Next, it is important to apply a waterproofing material.

A huge plus of this type of deflection is high rate of thermal insulation, as well as other mechanical characteristics... For example, strength and durability.

Speaking of the minuses, they are also there, or rather one. This is the price. It is quite high. And again, it will not work to carry out such a procedure on your own. Therefore, in this case, it is worth contacting professionals.

• If the roof has a minimum slope, then it is important to note that in this case, it is necessary to install the correct drainage systems... The bias itself is done exclusively to the side (funnel, gutter);
• If your roof is bituminous, it is worth making the slope angle less than 6 degrees, while the bottom layer of waterproofing must be made of membrane materials;
• It is very important to know that at low slope rates, it is necessary to perform ventilation of the under-roof space itself, with all the stingrays. The thickness of the gap also depends on the value of the angle (the larger the angle, the smaller the thickness, and vice versa).
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There are thousands upon thousands of architectural traditions around the globe in terms of the appearance of roofs. But modern architects have completely changed the idea of ​​the culture of suburban construction, introducing single-pitched roof forms as ideally combined with landscape design and diverse in execution. Of course, this new fashionable tone was set by the inhabitants of Australia, where the absence of snow in general as a natural phenomenon allows them to create with the architecture of residential buildings whatever their fantasy dictates.

But in the snowy regions of Russia, such a roof can be built, but with an appropriate slope and in the right direction. In a word, the main parameter of functionality is the angle of inclination of a pitched roof, which we will now teach you to calculate.

Step 1. Calculate permanent and dynamic loads

The first step is to calculate the load on the pitched roof. They are usually divided into permanent and dynamic. The first is the weight of the roof covering, which is always on the roof, such installations as antennas and dishes, a chimney, and so on. Those. everything that will be on the roof both day and night.

And dynamic loads, or, as they are also called, variable, are those that happen from time to time: snow, hail, people, repair materials and tools. And also the wind, which, well, loves to tear off lean-to roofs due to their windage.

Snow loads

So, if you make a slope of a pitched roof at 30 °, in winter the snow will press on it with a force of 50 kg per square meter. Just imagine that on your roof there will be one person for every meter! This is the load.

And if you raise the roof to above 45 °, the snow will most likely not be able to linger at all (it also depends on the roughness of the roofing). But for central Russia, where the snowfalls are moderate, it is enough to make a pitched roof within 35-30 °:

The minimum angle that must be in order for the snow to be able to come off the pitched roof itself is 10 °. And the maximum is 60 °, because it makes no sense to make the roof steeper. The same goes for snow, which clings even more to such a roof.

That is why the owners of lean-to outbuildings in winter often take up a shovel. Only the coverage area saves: the smaller it is, the less likely it is that the snow will be able to bend the material.

Wind loads

But in windy regions, it is impossible to build roofs with steep slopes at all. For comparison, an 11 ° slope of a pitched roof experiences exactly 5 times more wind force than a 45 ° slope. In view of this, keep in mind that a pitched roof is always made low to the leeward side.

Combined loads

And also be sure to calculate for a pitched roof such a value as a combination of the most unfavorable permanent and temporary loads. Those. that critical point that the rafter system must be able to withstand. This, by the way, is often forgotten! They think that the roof will withstand the snow, the wind too ...

But what if you and your friend have to climb onto the roof in a strong storm and snow? Is the structure designed for snow, wind, and the legs of at least two people at the same time? This is how troubles happen.

Step 2. Select the slope of the roof

The slope of a pitched roof is in a fairly wide range: from 6 ° to 60 °. It all depends on the area in which you are going to build: if you need to successfully dump tons of snow every winter, then make the slope steeper, if you plan to protect yourself from the wind, then flatter. And also from many other factors, including aesthetic ones.

Steep pitched roofs

The greater the angle of such a roof, the faster the water flows down it into the gutters. Neither leaves nor dirt will linger here, and therefore the roofing itself will last much longer. In addition, on such a roof, the visual aesthetics of the selected flexible tile or metal profile is more visible, which often plays an important role for the owners.

Low slope pitched roofs

The speed of rain and melt water flowing down on low-slope slopes is much lower, and therefore there is a risk of water stagnation, collecting dirt and ice getting stuck. On such roofs, moss develops quickly and foliage sticks. Especially if the roofing is rough.

As for rainwater, the main requirement for the roof is that the water on it, when snow melts or after rain, does not remain on the surface of the roofing material, but easily rolls down. If it has too low a slope (for a certain area), then the liquid will stand for a long time in all irregularities and seams. And the longer, the more chances it has to get inside and create many problems in the form of dampness, deteriorated insulation and corrosion of metal roof elements:



But, if a large roof of a house rises above such a building, then it's okay:



But here it still has its own plus: the smaller the angle of inclination of the pitched roof, the closer the geometry of the interiors is to the traditional cube. This means that it is perceived more easily and used with greater benefit.

Therefore, the lower the angle of inclination of such a roof, the more you need to take care of its waterproofing so that melt and rainwater cannot penetrate into the rafter system. Therefore, such roofing coverings as membranes, roll insulation or solid sheets are already needed here.

With a standard angle of inclination, a single-pitched roof is built as follows:



The minimum angle of a pitched roof

A pitched roof, the angle of which is only 3-5%, is often made inversion. Those. they subject it to certain additional loads: they walk on it, grow a garden on it, or even use it as an open terrace. Like here:



In addition, at a certain angle, the pitched roof directs the air flow in the desired direction, capturing precipitation and diverting it. Remember this!




Step 3. Determine the requirements for the slope

In functional terms, pitched roofs are divided into three main types: ventilated, non-ventilated and combined. Let's consider each option in more detail.

Ventilated design

These are equipped in closed-type buildings. Air vents and special voids between the insulating layers serve as ventilation, through which the air, passing, captures droplets of moisture from the insulation and carries them out.

If such ventilation is not provided, then moisture will remain inside the insulation (and it still gets into it, albeit a little), and the insulation will begin to dampen and deteriorate. And as a result, the entire roofing pie will gradually collapse.

But a ventilated pitched roof has its limitations. So, the angle of inclination can only be in the range from 5% to 20%, otherwise the air will not be able to efficiently pass through the vents.



Non-ventilated design

This type of pitched roof is advantageously built on terraces and outbuildings. Typically, the angle of such a roof is in the range of only 3-6%, although there are no restrictions to it.

Ventilation in such roofs is not needed because the air in a room without walls or with wide doors often open (as in the case of a garage) ventilates well itself, carrying any water vapor outside. Which, by the way, by themselves, are not particularly formed in such buildings:



Combined design

Such roofs combine the device of both previous types. Here, the desired roof slope is provided by thermal insulation. It turns out economically, but in winter you have to constantly clean off the snow.

But the device of such a pitched roof is already different, because dynamic and dynamic loads are now added to the variable and static loads. And usually everything looks like this: the bottom is corrugated board, on it there are two layers of insulation and good waterproofing.

The angle of the shed roof also depends on parameters such as the type of connection of the rafters to the Mauerlat or walls. Let's take a closer look.

Step 4. Calculate the exact slope angle

The angle at which the rafters and the roof slope are inclined to the horizontal plane of the ceiling is called the angle of a pitched roof. And take this scheme seriously if you want to provide your roof with the correct mechanical strength:



The angle of inclination of the slopes is measured in percent and degrees. But, if it is even more or less clear with degrees (thanks to the school geometry course), then what are percentages? Percentage is the ratio of the difference in the height of the ridge and eaves to the horizontal of the ramp, multiplied by 100.

There is another interesting point: many architects specially calculate the angle of the pitched roof so that it is equal to the angle of the sun in a given area in mid-spring. Then you can calculate up to a millimeter when and what kind of shadow will be, which is important for planning terraces in front of the house and other recreation areas.

Step 5. Limiting the range of choice of roofing

Modern roofing materials also have their own requirements for the minimum and maximum angle of inclination of a pitched roof:

• Decking: min 8 ° - max 20 °.
• Seam roofing: min 18 ° - max 30 °.
• Slate: min 20 ° - max 50 °.
• Soft roof: min 5 ° - max 20 °.
• Metal tiles: min 30 ° - max 35 °.

Of course, the smaller the angle, the cheaper materials you can use: roofing material, corrugated board and the like.

You will be surprised, but especially for low-slope roofs today, the same types of roofing are being developed that are usually used with a slope of at least 30 °. What for? This is the fashion in Germany, which has come down to us: the lean-to roof is almost flat, and the roof is stylish. But how? It's just that manufacturers improve the quality of the locks, make the overlap area larger and carefully consider the protection from dirt. That's all the tricks.

Step 6. We decide on the rafter system

And from the chosen angle of inclination of the roof and the loads planned for it, we determine the type of fastening of the rafters to the walls. So, there are three such types in total: hanging rafters, layered and sliding.

Hanging rafters

Hanging rafters are the only option where the connection must be rigid, but for the rafters between the side supports there is no way to support.

Simply put, you only have external load-bearing walls, and no partitions inside. Let's say this is a rather complex rafter system, and its construction must be approached with responsibility. The whole problem is in large spans and in the pressure that is applied to the walls:



Or like in this project:




Rafters

Here, the entire roof presses on at least three supports: two outer walls and one inner one. And the rafters themselves are used here dense, with a section of at least 5x5 cm of bars and 5x15 cm of rafter legs.

Sliding rafters

In this rafter system, a log in the ridge serves as one of the supports. And to connect the rafters with it, such special elements as "sliders" are used. These are metal elements that help the rafter to move forward a little when the walls are shrinking to avoid cracks. Very little! And thanks to this device, the roof easily tolerates even a rather noticeable shrinkage of the log house, without any damage.

The bottom line is simple: the more knots in the rafter system, the more flexible and durable it is. The more a pitched roof is able to withstand the pressure of the weight of the roofing and snow, and at the same time not break. But there are rafter systems where the connection is generally static:



Step 7. Calculate the height of the pitched roof

Here are the three most popular ways to accurately calculate the correct height for your future roof.

Method number 1. Geometric

A pitched roof looks like a right-angled triangle. The length of the rafter leg in this triangle is the hypotenuse. And, as you remember from the school geometry course, the length of the hypotenuse is equal to the root of the sum of the squares of the legs.

Method number 2. Trigometric

Another option for calculating the length of the rafter legs is as follows:

1. Let us denote by A the length of the rafter beams.
2. Let's denote by B the length of the rafters from the wall to the ridge, or the length of the part of the wall in this area (if the walls of your building are of different heights).
3. Let X denote the length of the rafters from the ridge to the edge of the opposite wall.

In this case, B = A * tgY, where Y is the angle of inclination of the roof, and the length of the slope is calculated as follows:

X = A / sin Y

In fact, all this is not difficult - just substitute the required values, and you will get all the parameters of the future roof.

Method number 3. Online calculators

Calculated? Now let's move on to building the roof itself:



We hope you figure it out easily!