How to measure the angle of the roof of a house. How to correctly calculate the angle of inclination and height of a shed roof. Why do you need a minimum slope

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Building any roof is not as easy as it seems. And if you want it to be reliable, durable and not afraid of various loads, then beforehand, even at the design stage, you need to make a lot of calculations. And they will include not only the amount of materials used for installation, but also the determination of the angles of inclination, the area of \u200b\u200bthe slopes, etc. How to calculate the angle of the roof correctly? It is from this value that the rest of the parameters of this design will largely depend.

The design and construction of any roof is always a very important and responsible business. Especially when it comes to the roof of a residential building or a roof with a complex shape. But even the usual shed, installed on a nondescript shed or garage, just needs preliminary calculations.

If you do not determine in advance the angle of inclination of the roof, do not find out what optimal height the ridge should have, then there is a great risk of building a roof that will collapse after the first snowfall, or all the finishing coating from it will be torn off even by a moderate wind.

Also, the angle of inclination of the roof will significantly affect the height of the ridge, the area and dimensions of the slopes. Depending on this, it will be possible to more accurately calculate the amount of materials required to create the rafter system and finish.

Prices for various types of roof ridges

Roofing ridge

Units

Remembering the geometry that everyone learned in school, it is safe to say that the angle of the roof is measured in degrees. However, in books on construction, as well as in various drawings, you can also find another option - the angle is indicated as a percentage (here we mean the aspect ratio).

Generally, slope angle is the angle formed by two intersecting planes- overlapping and directly the slope of the roof. It can only be sharp, that is, lie in the range of 0-90 degrees.

On a note! Very steep slopes, the angle of which is more than 50 degrees, are extremely rare in their pure form. Usually they are used only for the decoration of roofs, they may be present in attics.

As for measuring the angles of the roof in degrees, then everything is simple - everyone who studied geometry at school has this knowledge. It is enough to sketch a roof diagram on paper and use a protractor to determine the angle.

As for the percentages, then you need to know the height of the ridge and the width of the building. The first indicator is divided by the second, and the resulting value is multiplied by 100%. Thus, the percentage can be calculated.

On a note! At a percentage of 1, a typical degree of inclination is 2.22%. That is, a slope with an angle of 45 ordinary degrees is equal to 100%. And 1 percent is 27 minutes of arc.

Table of values - degrees, minutes, percent

What factors affect the angle of inclination?

The angle of inclination of any roof is influenced by a very large number of factors, ranging from the wishes of the future owner of the house to the region where the house will be located. When calculating, it is important to take into account all the subtleties, even those that at first glance seem insignificant. At some point, they may play their part. Determine the appropriate angle of inclination of the roof should be, knowing:

types of materials from which the roof pie will be built, starting from the truss system and ending with the exterior finish;
climate conditions in the area (wind load, prevailing wind direction, precipitation, etc.);
the shape of the future building, its height, design;
purpose of the building, options for using the attic space.

In those regions where there is a strong wind load, it is recommended to build a roof with one slope and a small angle of inclination. Then, with a strong wind, the roof is more likely to resist and not be torn off. If the region is characterized by a large amount of precipitation (snow or rain), then it is better to make the slope steeper - this will allow precipitation to roll / drain from the roof and not create additional load. The optimal slope of a shed roof in windy regions varies between 9-20 degrees, and where there is a lot of precipitation - up to 60 degrees. An angle of 45 degrees will allow you to ignore the snow load in general, but in this case the wind pressure on the roof will be 5 times greater than on a roof with a slope of only 11 degrees.

On a note! The larger the roof slope parameters, the more materials will be required to create it. The cost increases by at least 20%.

Pitch angles and roofing materials

Not only climatic conditions will have a significant impact on the shape and angle of the slopes. An important role is played by the materials used for construction, in particular - roofing.

Table. Optimum slope angles for roofs of various materials.

On a note! The lower the roof slope, the smaller the pitch used to create the crate.

Prices for metal tiles

metal tile

The height of the skate also depends on the angle of the slope.

When calculating any roof, a rectangular triangle is always taken as a guideline, where the legs are the height of the slope at the top point, that is, at the ridge or the transition from the lower part of the entire rafter system to the top (in the case of mansard roofs), as well as the projection of the length of a particular slope on horizontal, which is represented by overlaps. There is only one constant value here - this is the length of the roof between the two walls, that is, the length of the span. The height of the ridge part will vary depending on the angle of inclination.

Knowing the formulas from trigonometry will help to design the roof: tgA \u003d H / L, sinA \u003d H / S, H \u003d LхtgA, S \u003d H / sinA, where A is the angle of the slope, H is the height of the roof to the ridge area, L is ½ of the entire length roof span (with a gable roof) or the entire length (in the case of a shed roof), S - the length of the slope itself. For example, if the exact value of the height of the ridge part is known, then the angle of inclination is determined by the first formula. You can find the angle using the table of tangents. If the calculation is based on the angle of the roof, then you can find the ridge height parameter using the third formula. The length of the rafters, having the value of the angle of inclination and the parameters of the legs, can be calculated using the fourth formula.

The metal tile is considered one of the most convenient and popular roofing materials. Featuring a high bearing capacity, strength, ease of installation, metal tiles are little subject to mechanical stress. When planning the layout of the material, it is necessary to calculate the correct slope for the metal tile and observe the technological details of installation. Then the roof will serve for a long time and will not require an early renewal.

The slope of the roof is an important defining structure, formed by the angle cut off by the floor plane and the roof slope. The indicator is expressed as a percentage or degrees, calculated by dividing the height of the ridge by 1/2 of the width of the building. The angle of inclination of a roof made of metal tiles is regulated by SNiP and the supplier's instructions. The indicator depends on factors such as:

Roof covering application.
The ability of the roof to effectively remove natural precipitation, withstand winds and other climatic phenomena.
Roofing price.
The mass of the roofing cake.

A fairly new coating, metal tile, is not so strictly regulated by standards. Therefore, the manufacturer himself often advises the minimum angle indicator, based on the technical characteristics of the product. The calculation is made according to the thickness of the sheet, the bearing capacity of the base and the method of laying the roofing. However, there are optimal values that you should rely on:

With a slope of 6 meters in length, the minimum slope according to SNiP must be at least 14 °.
The permissible slope of the roof of metal tiles should be in the range of 14-45 °.
The optimal value of the angle is 22°, this indicator is sufficient for the normal removal of precipitation with a slope area of less than 6 meters.

The choice of the roof slope is not always simple, therefore, based on the indicators of SNiP, one should take into account the following recommendations for the equipped slope slope:

The level of snow load in the construction region. To determine the indicator, you need to take information from the directory and calculate the average annual amount in the winter. The thicker the snow cover, the greater the level of slope, otherwise the snow mass will linger on the roof, which will lead to deformation of the sheets.
Wind load - the indicator also depends on the characteristics of the region. At the maximum intensity of wind flows, the angle of inclination is small, which reduces the windage of the slopes.

Advice! The number of hurricanes, tornadoes and other natural disasters is also taken into account. The information is taken from reference books.

Features of metal roofs with a small slope

The lowest slope angle is 14 °, but experienced roofers lay materials when calculating an angle of 10-14 °. And to ensure the reliability of the roofing carpet and reduce the risk of leaks, the following actions are performed:

The frequency of the laths in the crate increases by reducing the inter-rafter step.
The rafter system is strengthened by means of a frequent or continuous crate.
Significantly increase the number of overlaps! Despite the recommendations of manufacturers for a horizontal overlap of 8 cm, a vertical overlap of 10-15 cm, the overlap increases by the width of the wave. Thanks to this method, the strength of the roofing carpet increases and the risk of leaks on the roof of a small slope is eliminated.
Carefully seal the joints with a silicone-based sealant.

Advice! All measures taken are temporary, so a visual inspection of the roof once a year will not hurt.

Determination of the roof slope by geometric dimensions or in degrees

The formula for calculating the steepness of the slope for a roof made of metal by size, for example, for a gable roof, is calculated using the following formula: I = H / (1/2L), where:

I - the desired angle for the metal tile;
H - the distance from the border of the ceiling to the ridge, that is, an indicator of the height of the rafter structure;
L - dimensions of the width of the building.

To find the percentage, the resulting index i is multiplied by 100. And for the expression in degrees, you should use the trigonometric function or find the value in the corresponding table:

degrees	%	degrees	%	degrees	%
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

Important! This type of calculation is suitable for single, double-pitched roofs. For a single-slope, the entire span length is taken into account. In the case of arranging a roofing carpet with an asymmetrical slope, the roof angle is calculated from the distance from the projection point of the ridge element to the ceiling for each slope separately.

The optimal angle for a roof with complex structural elements is taken into account by the correction factor for the projection in the horizontal direction:

Roof angle 1: 12 (7°) - K = 1.014;
1:10 (8°) = 1.020;
1:8 (10°) = 1.031;
1:6 (13°) = 1.054;
1:5 (15°) = 1.077;
1:4 (18°) = 1.118;
1:3 (22°) = 1.202;
1:2 (30°) = 1.410.

Criteria for choosing the angle of inclination

When calculating the angle of inclination of a roof for a metal tile, you need to know that a small steepness has its advantages:

economical consumption of materials;
reduction in the weight mass of the roofing carpet, the sheet windage index, which minimizes the risk of defects during heavy winds;
convenience and simplicity of arranging drainage systems.

But there are also disadvantages, if the slope of the roof is minimal, then:

it is necessary to seal the joints as much as possible, since the almost complete absence of a drain increases the possibility of moisture penetration through the attachment points;
it will be necessary to remove snow blockages on the roof more often so that the metal tile is not subjected to increased load;
the need to equip a powerful crate will require a calculation of the bearing capacity of the base and complicate the fastening of roofing elements;
under a flat roof, it is not always possible to equip spacious residential / non-residential premises.

But if the slope of the roof is large, for example, 45 °, then, despite the free melting of the snow cover, the mass of the coating is increased, due to which the sheets simply slide off. The way out is to strengthen the fasteners and strict adherence to the installation technology of the roofing carpet. In addition, when the angle of inclination of the metal roof is too steep, the consumption of roofing material increases, as with the arrangement of curly slopes.

In order not to calculate which angle will be better, take as a basis the recommendations of experienced roofers: for shed roofs it is 20-30 °, for gable roofs - 25-45 °. And a little advice: when arranging the lathing with frequent steps, a kind of shock-absorbing cushion is obtained that strengthens the roofing carpet. Knowing the calculation formula, it is easy to calculate different options for the steepness of the slopes and decide which angle to give preference to, depending on weather, climatic conditions and the financial component: whatever one may say, material consumption is less on roofs with a minimum slope.

The content of the article

The roofs of private houses, as a rule, always have slopes - this roof design is the easiest to operate and maintain. Water and snow are better and faster to leave such roofs, which guarantees excellent waterproofing. And the appearance of a private house becomes more attractive.

In addition, there is an additional room in the attic, which can be used for living and building an attic or for numerous household needs.

Factors affecting the shape of the roof

To make the roof reliable and comfortable, it is necessary to correctly calculate the angle of the roof slope, which depends on many reasons. First of all, these are the climatic conditions of residence and the characteristics of the roofing material. Natural conditions affecting the size of the roof slope:

as the roof slope increases, the wind load on the roof structure increases. For example, if the angle of inclination is increased from 10 degrees to 45 degrees, then the load on the structure due to wind will increase five times. If the angle is made small, less than 10 degrees, then there is a high probability of a breakdown of the coating sheets due to a strong wind that falls under the joints;
atmospheric precipitation in the form of rain and snow also affect the slope of the roof. With an increase in the slope, precipitation better descends from the roof slopes. The greatest snow load in winter occurs on slopes with a roof slope of about 30 degrees. At an angle of 45 degrees, the snow will melt completely.

With a small slope of the roof slopes, as a result of strong gusts of wind, water can get under the joints of the coating.

In the question of what angle of the roof slope needs to be made, the type of roofing matters:

When using metal tiles as a roofing material, it is necessary to take into account the considerable weight of this coating. Therefore, the angle of inclination of the roof should not be very large. This is especially important in areas where constant and strong winds prevail, as the mechanical load on the roof structure increases. For this coating, the minimum slope angle is approximately 22 degrees.. In this case, moisture will not accumulate, but will be effectively removed from the roof. In addition, the joints of the coating will be reliably protected.
The professional flooring is the most popular roof covering now for private houses. It is lightweight, easy to install and maintain the roof. The minimum roof slope angle using this material is 12 degrees.
When using rolled materials, they are also called soft roofing, the slope angle of the slopes depends on the number of coating layers. For a coating that consists of two layers, the minimum angle of inclination is up to 15 degrees. For three layers, this value should be between two and five degrees. If the roof needs to be covered with a membrane coating, the angle of inclination should also be between two and five degrees.

From the above, we can conclude that the decision on the optimal angle of the roof slope depends on the natural conditions, the type of roofing material and the capabilities of the owner of the house.

With a large slope, the consumption of materials during the construction of the roof increases.

In addition, the type and pitch of the crate depends on the slope of the roof slopes. The smaller the slope of the roof, the smaller the step of the crate should be.. For minimum angles, it is approximately 35 to 45 centimeters.

with a roof slope of up to ten degrees, roofing can be done using crumbs of stone and gravel;
if the roof slope is more than ten degrees, then waterproofing using bituminous materials should be used. For rolled materials, it is necessary to use an additional protective coating;
when using corrugated board and slate, sealing of joints and seams is recommended, the joints should be double.
If the amount of precipitation in the area where the residential building is located is high, then the angle of inclination is best done at 45 degrees. With a minimum amount of precipitation, the roof slope can be made at 30 degrees. In strong and frequent winds, the angle of inclination should be between 15 and 20 degrees. If the wind loads are small, then it is better to make a roof, the angle of inclination of which is from 35 to 40 degrees.

When calculating the angle of inclination of the roof, it must be taken into account that the higher the average annual temperature and the less precipitation, the more flat the roof can be built.

It should be taken into account that the type and design of the drainage system of the whole house depends on the slope of the roof.

The choice of the angle of inclination of the roof, depending on various factors

When determining the slope of a roof, there is no perfect solution that will suit all climatic requirements. Here it is important to find the best option, which depends on the consumption of materials and costs.

The larger the roof area, the more expensive it is.

The recommended roof slope angle is between 20 and 45 degrees.. With its increase, it is necessary to take into account the creation of additional structures to strengthen the entire structure. And a decrease in the angle will lead to additional costs of materials to ensure normal waterproofing of the roof of the house.

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

Peculiarities

In modern projects of country mansions, 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, regulatory requirements are still in the foreground, because the roof, first of all, must be reliable. Therefore, often architectural delights fade into the background.

Roofing should fulfill its intended purpose - to protect against moisture. In some cases, thermal and sound insulation is required. This may be necessary to increase the functionality of the premises under the roof. Therefore, the design of the roof can not 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 made using the appropriate software.

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

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

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

one horizontal plane;
one flat roof slope.

This parameter is measured from the top edge to the base of the truss system. When calculating, only acute angles are taken into account, since there are no obtuse-angled slopes by definition. Steep slopes are rare. As a rule, they are used for decoration (for example, when building turrets in the Gothic style).

Mansard roofs can be steep. In this case, the lower rafters are placed 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 indicating degrees.

The value of the oblique 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 graphs. Depending on the indicators, roofs are usually divided into types.

Kinds

Experts distinguish several main types of roofs.

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

Double roof. It is a reliable, easy-to-install option. The roof includes two slopes connected at a right angle.

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 design, such roofs are very economical in terms of material consumption.

Vaulted type of roof. It is rare, as it involves a limited choice of materials. Such options are built 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 type of roof. It is complex in configuration, but very beautiful. Such a roof is difficult to lay due to the many junctions and lintels.

Also, experts identify types of roofing that can be subsequently exploited., and options that are not subject to exploitation. If professionals rank the roof as unexploited, 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 pitched roof.

Shed roofs are the most beneficial for construction. They require a minimum of material costs, but the work can be done independently. If the roof has a slight slope, then on its surface it is possible to realize a place of rest without constructing a complex attic.

The space under the roof can be used if the type of roof 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 a roof is connected with many nuances. One of the main ones is the climatic factor.

Climate influence

For example, a huge load on the truss structure may arise due to wind. Even a slight increase in the slope angle increases the wind load. For example, if the angle of inclination of the roof is 30 degrees more than the standard values, the wind load becomes five times greater. Therefore, even a slight increase in performance can play a cruel joke on the owner of the house during a natural disaster.

No less destructive effect on the quality of the roof precipitation. At the same time, a well-chosen slightly larger slope will avoid the accumulation of snow on the surface. There will be no snow melting 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. It is obvious that snow does not linger on high slopes. However, it is generally accepted that some snow layer on the roof plays the role of additional thermal insulation.

To eliminate the risk of a break in the roofing material, a strong rafter system is carried out, because a lot of weight will affect the entire structure.

It is worth remembering that the greater the slope of the roof, the more funds will have to be spent on construction. Also, costs are associated with the choice of roofing 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 laid on a roof 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 smaller degree, roofing material and other bituminous materials can be used, which are mounted in one piece.

Profiled sheet manufacturers claim that this material can be laid at a minimum allowable 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 tiles, the minimum possible slope of the 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 mounting location of the ridge board changes. The method of mounting the skate itself also changes. For small values, an aero roller is attached between the ridge bar and the tile. It does not allow snow to penetrate under the roof.

For a roof covered with ondulin, the minimum possible slope is 6 degrees. For soft tiles, the optimal surface slope is 11 degrees. Although for this material a larger slope is acceptable. In this case, the crate must be necessarily 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 determined by excellent technical characteristics and long service life.

When choosing one or another 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 slope angle is small, then a solid crate is mounted. Also, when installing a flat roof, a drainage system is required. For any type of roofing, there are regulatory parameters. They should be kept in mind even if the simplest flat option is chosen.

Standard values

Arranging a flat roof is a simple undertaking. The main thing is to use the right high quality material. Equally important is the slope of a flat roof.

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

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

To date, on sale you can find special plates that are distinguished by high thermal insulation qualities. Such plates are wedge-shaped. It is enough to lay the material on a flat surface. You will get a slope that meets the standard 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 absolutely flat. Then beacons are installed on it. The slope should be directed to the drains.

When creating a slope, it is worth considering the area of \u200b\u200bthe roof. For the roof of a garage, for example, it is worth considering one slope, which will be directed into the drain funnel. Razuklonka for a standard house measuring 80 square meters. m will be 2-4 slope. At the same time, all of them must be sent to the drainage system in order to freely deliver water to it.

How to calculate?

If there are usually no difficulties with arranging a flat roof, then engineering calculations are necessary to install a roof with several slopes. The easiest way to calculate and determine the values \u200b\u200bis in degrees. For example, for arranging a roof with a sloping angle of 30 degrees, you can use the mathematical method.

This will require 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).
Pawn (L). This is the horizontal length from the middle of the bottom of the slope to the eaves.

Mathematical calculation is made according to the formula. You can calculate the desired parameter like this: I \u003d H: L. For example, the laying length is 5 m, and the height is 3 m. In this case, the slope will be equal to 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 convert relative values. With the values from the above example, the angle of inclination will be 30 degrees.

Specialists in their measurements do not always use a conversion table. The coefficient in percent can be used in the same way as the coefficient in degrees. In general, professionals use special tools in calculations. For example, you can measure the area parameter using a special inclinometer.

The tool is a ruler with a rail. One axis contains the usual scale in centimeters, the other - the pendulum. If the scale bar is horizontal, then the pendulum will indicate zero. When measuring the slope, the rail is set 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 both drip-type devices and electronic devices. In this regard, the mathematical method of measurement cannot be considered relevant. Modern devices allow you to make more accurate calculations.

The reliability of any building, as well as the comfort of living in it, depend mainly on how well its roof is arranged.

And one of the criteria for the quality of the roof is its slope.

Since the amount of roofing material also depends on its size, the choice of the angle of inclination and its preliminary calculations are made before the purchase of the selected roofing material begins.

What influences it

Depending on the magnitude of the slope of the roof slopes, the peculiarity of its operation depends.

It is customary to distinguish 4 types of roofs:

high, with an angle of 45-60 degrees;
pitched, with a slope of 30 to 45 degrees;
gentle, the slope angle of which is 10-30 degrees;
flat. A slope of 10 degrees or less.

The choice of the value of this parameter is influenced, first of all, by natural factors that are characteristic of the area.

Strong wind exerts the greatest pressure on high roofs.

Because such roofs, due to the large angle of inclination, have a very large area.

A large surface area has a very high windage.

Accordingly, the load on the entire structure of the truss system is very high.

And if you decide to arrange a high roof with a very large slope, then you should take care of a very solid foundation.

However, in areas where strong winds prevail, it is unsafe to arrange and flat roofs.

With this type of roof, increased pressure will be exerted on the lower part of the slope in strong winds.

And if the roof fastening is weakened, the entire structure may fail.

Therefore, in areas where strong winds are frequent, it is recommended to arrange pitched roofs with a slope of 25 - 30 degrees.

If the wind force is small, then the slope of the roof can be 30-45 degrees.

If in the area where the house is being built, during the cold season there is heavy snowfall, then a roof with a large slope angle should be built.

In this case, the high roof is out of competition.

On roofs with a large slope, snow does not linger.

It is for this reason that in all northern countries the roofs on buildings are very high (Sweden, Finland, Norway, etc.).

The smaller the angle of the roof slope, the longer the fallen snow will be on the slopes.

The more weight will affect the entire structure.

If the design of the truss system is made with a large margin of safety, then some layer of snow on the roof is not bad.

It provides a little extra insulation.

However, if the design of the truss system of the structure is not designed for a large load, then there may be big problems.

Choosing a slope depending on the roofing material used

Gone are the days when only two types of roofing materials were used for covering: tiles and slate.

There are a lot of roofing materials today!

Each material has its own individual technical characteristics and this must be taken into account when calculating the required value of the angle of inclination.

After all, it may happen that the material you like in terms of its parameters simply does not fit.

Minimum Tilt Angle

There is a concept of the minimum value of this parameter.

For each of the materials, this parameter is different.

And if the angle of inclination obtained as a result of your calculations turns out to be less than the minimum value for the roofing material you have chosen, then you cannot use it for roofing.

In the future, a lot of problems can arise if you violate this rule:

for any piece of stacked roofing materials, such as tiles or slate, the minimum slope is 22 degrees. It is with this value that moisture does not accumulate at the joints and moisture does not seep inside the roof;
the angle of inclination for rolled materials (roofing felt, bicrost, etc.) depends on how many layers you plan to lay. If there are three layers, then the slope can be 2-5 degrees. If there are two layers, then it needs to be increased to 15 degrees;
corrugated board manufacturers recommend that when constructing a roof from this material, arrange a slope angle of 12 degrees. Decking can also be used at lower values, but in this case it is necessary to glue the joints of the sheets with a sealant;
for metal tiles, the value of this parameter is 14;
for ondulin - this is a value of 6 degrees;
the minimum slope for soft tiles is 11 degrees. But at the same time, a prerequisite is a continuous crate;
for membrane roofing there are no strict requirements for the minimum value of this parameter.

It's about the minimum values.

My advice is to stick to these rules.

So that in the middle of winter you do not have to re-roof the entire roof.

Now about the optimal values

If it rains and snows often in the region, then the roof will be optimal, the angle of inclination of the slopes of which will be 45 - 60 degrees.

After all, it is necessary to remove the load from water and snow from the roof as soon as possible.

Because the strength of the truss system is not unlimited.

And thanks to the large slope of the roof, rain and snow will descend as quickly as possible.

If in the region where the house is built, there are constantly strong winds, then the roof is treated differently.

With a smaller slope, its windage decreases.

And there is no exorbitant load on the roofing material and rafters.

Also, the roof will not tear off during sudden gusts of wind.

In this case, the optimal angle of the roof slope is 9 - 20 degrees.

Very often in the region there is both snow and wind.

For example, the Orenburg region.

In this case, choose the average value of the angle of inclination.

As a rule, its value is in the range of 20 - 45 degrees.

If you pay attention, most pitched roofs have exactly this meaning.

We calculate its value

For lean-to

Since the shed roof rests on walls of different heights, the formation of a given angle of inclination is carried out by simply raising one of the walls.

We draw a perpendicular L sd along the wall, originating at the point where the short wall ends and resting on the wall with the maximum length.

The result is a right triangle.

If the length of the wall L cd is 10 meters, then in order to obtain a slope angle of 45 degrees, the length of the wall L bc must be equal to 14.08 meters.