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Choosing the right slope angle for a roof is not only an aesthetic task, but, to a greater extent, a practical one. Indeed, the performance of the coating, the protection of the building from atmospheric influences - first of all, precipitation, the durability of the structure and the consumption of materials will depend on this parameter. Due to a number of features of the material, the minimum slope of a roof made of metal tiles is more important than for other materials, and is less flexible.
First of all, you should decide what a slope is, and why it is needed at all and how to cover the roof with a metal tile. The slope is the angle between the floor plane and the rafters.
It is calculated using a common fraction as follows:
i = h: (1/2L), where:
i - slope
h - the height of the ridge above the ceiling
L - the width of the building, or the width distance covered by this section of the roof (for broken roofs, where the slope can vary within one slope)
For example, with a building width of 8 m and a ridge height of 3 m, the slope will be: 3:4 = 3/4, or 0.75. To express as a percentage, this value is multiplied by 100: \u003d 75%
However, the angle is sometimes expressed in degrees - both systems have equal circulation.
At the same time, in degrees, the actual geometric value of the slope is displayed - the angle between the rafters and the ceiling.
These values do not match, which often causes confusion and errors - among the builders, and sometimes - among the compilers of the instructions.
Knowing the sides of the triangle, it is not a problem to translate one value into another.
However, for those who do not like to bother with calculations of metal roof tiles, there are special translation tables, such as the following:
| Degree | Percent | Degree | Percent | Degree | Percent |
| 1 | 1,8 | 16 | 28,7 | 31 | 60,0 |
| 2 | 3,4 | 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 | 8,8 | 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 | 19,4 | 26 | 48,7 | 41 | 86,0 |
| 12 | 21,2 | 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 |
Although the roof is designed in conjunction with the entire building, there is still some room for maneuver until the truss system is created, whether the roof slope is calculated from metal tiles, slate, or any other material.
If the foundation and walls have a certain margin of safety, then, at least within the same roofing material, the shape and slope of the roof can be varied.
Since the width of the building is a fixed value, and the length of the rafters is determined by the distance between the ridge and the place of support on the wall, the ability to change the angle of the roof remains only the height of the ridge.
When the owner of the building has determined which slope he considers optimal for himself, the following table will help calculate the height of the ridge
To get the result, you need to take half the width of the overlap, find the desired angle in degrees in the table, and multiply it by the coefficient in the corresponding line.
The resulting value will be the required height of the skate. All these calculations are also applicable to a shed roof - but then they need to take not half the width of the roof, but the full one, and instead of the ridge, the height of the largest of the outer walls will appear.
The same is true for hip (four-pitched) roofs, but in this case, the slope of the end slopes is measured from the middle of the wall to the place where the slope rests on the end of the ridge.
To display the desired height of the skate "in place" there is a simple way. It is necessary to put marks on each of the outer walls along which the slope will go (it is better that they are in the center of the length of the walls).
A cord is sequentially pulled between opposite marks, you can beat off a line along it with chalk. Exactly in the middle of the cord (measured with a tape measure), you need to install a bar perpendicular to the overlap (checked with a corner).
Now, by moving the twine up the plank, you can measure the angle against the wall to determine in which position the twine will achieve the required slope. At this point, a mark is placed on the bar.
If you now saw off the rail in this place, you will get a template that will allow you to easily cut the required number of ridge supports of the desired size.
If the supports are not supposed, then the same operation can be carried out from each of the ends, fix the measuring rails, and pull the cord along their top. He will indicate the desired height of the joining of the rafters.
What is the slope of the roof? Two groups of factors can be distinguished - positive and negative, to which its increase leads.
Positive:
- Rain falls on the roof at a large angle, which virtually eliminates the possibility of falling between the elements of the coating, as well as under the overhang
- With large slopes, the snow load on the roof is reduced, and at angles of 45 ° it is not taken into account at all. Eliminates the need for a snow retention system
- The main power load on the roofing material goes “on a shift” in the direction of the slope, which is handled quite reliably by standard fasteners - nails and self-tapping screws
- Possibility of creating under-roof spaces, attics of a larger area and with more correct geometry
Negative:
- Increased consumption of roofing material - for example, changing the slope from 15° to 45° on a simple roof will increase the required coverage area by more than 20%
- The increasing weight of the roof - after all, both the mass of the coating and the supporting structures will increase
- Large windage, and, accordingly, wind load
- The complexity of organizing a drainage system - a large area of \u200b\u200bthe roof falls on a running meter of a sewer pipe, the flow of water through it descends at a higher speed. It is not a fact that for any slope it will be possible to select the appropriate section of the gutter tray - and this will require a drainage device in several tiers
Ultimately, the truth is somewhere in the middle - and here each homeowner is tied to his climate zone,financial resources and other factors.
But, if a metal roofing device is chosen, the manufacturer's instructions impose certain restrictions.
Different companies have different allowable values - from 12° (and even - 10°) to 15°.
Since the material is relatively new, there are no SNiP requirements for this parameter for it. But practice suggests that nevertheless this angle should be at least 14 °.
If the manufacturer does not stipulate special restrictions on the maximum angle, it can be accepted by anyone.
However, the "average" angles in terms of snow load are the most inefficient. It has been experimentally proven that in winter, snow accumulates most actively on roofs with a slope of 20-35 °
This value is determined by the specifics of the material. The strength of a metal tile is its flexibility, which allows you to form rather complex structures with a roof made of metal with your own hands.
But this is also its weakness, because with a small slope, or a large snow load, even a powerful carrier system does not save.
For example, the installation of a valley when roofing with a metal tile is carried out along a continuous crate. However, even this does not save at small laying angles.
After all, since the groove is the inner junction of the slopes, and in winter, the formation of snow pockets is possible here. The increased mass of precipitation presses on the metal and bends it, opening access to the under-roof space.
In the event of a thaw and subsequent cooling, frozen water fixes and expands the cracks, contributing to further leaks.
A small slope contributes to the same effect in heavy rain - the water does not have time to go down the slope, and exerts high pressure on the roof. Metal tiles with a large wave height are less susceptible to this - its bending strength is higher.
The entire metal tile is a directional material, that is, it can be mounted in only one position. Therefore, a special rubber seal is placed at the bottom of each sheet, which somewhat reduces the effect of precipitation.
However, with intensive exposure, sealing should be carried out at least once every 3 years, otherwise a major overhaul of the roof cannot be avoided.
But the flexibility of the metal tile also affects its resistance to wind loads - if they are directed into the plane of the sheet and fall on a reliable crate - there will be no problems.
But if gusts hit from the bottom or side end, creating a tearing effect, sooner or later the material will bend or tear off. Therefore, the protrusion beyond the edge of the crate is made so small - 40-50 mm, and the wind slats are attached both from the ends and from the eaves.
Summing up all the factors, we can say that the minimum slope required by the installation instructions for a metal roof is an ideal value, assuming that all requirements for installation technology will be impeccably met.
By setting a greater bias, you will, of course, have to spend money on an increased amount of material. But at the same angle of 45 degrees, you can save on installing expensive snow retainers, and be calm about possible excessive snow and rain loads on the roof, getting under the wind overhang and blowing rain spray there.
In the process of building residential cottages and buildings for other purposes, metal tiles are often used to cover the roof. This material is quite beautiful, modern, durable and reliable. But in order for the metal tile to fully show its positive qualities, it is necessary to take into account many different parameters in the design and installation process. One of these parameters is the minimum slope of a metal roof. Consider what it is.
In the design and construction of the roof, there are no trifles that could be called insignificant and insignificant. So, a properly selected minimum angle of inclination of a metal roof not only affects the aesthetic perception of the roof, but also has quite practical significance.
The fact is that the performance of the coating, namely its protective properties, depends on the height of the slope of the slope. In addition, the overall design of the roof, as well as such a parameter as material consumption, will depend on the location of the slopes.
What is slope slope?
First you need to figure out what the slope of a metal roof is and how it is determined. So, the slope of the slopes is the angle that is formed between the rafters and the floor plane. The slope calculation formula is as follows:
In this formula, the symbol I indicates the slope of the slopes, the symbol H is the height measured from the ceiling to the upper part of the ridge, and the symbol L indicates the width of the roof.
Advice! In calculations performed for sloping roofs, it is necessary to calculate the slope for each section separately. In this case, the formula does not take into account the total width of the building, but the width of the part that is covered by this section of the roofing.
For example, you need to calculate the slope of the slope for a roof with a width of 8 meters and a ridge height of 3 meters. According to our formula, it turns out - 3: 0.5 X 8 \u003d 0.75. If the angle of inclination is expressed as a percentage, then the result of the calculation must be multiplied by 100%. For our example, the slope of the slope will be 75%. 
However, the slope of the slope is expressed not only as a percentage, but also in degrees, moreover, both measurement systems are used equally often. When expressing the magnitude of the slope in degrees, the actual angle that the rafters form with respect to the floor surface is measured.
Advice! Using different calculation systems can lead to considerable confusion, so you should always pay attention to whether this value is expressed in degrees or as a percentage. To convert one value to another, you can use geometric formulas, but it is possible to do it easier by referring to ready-made conversion tables for the values \u200b\u200bgiven in the reference books. So, if in percent the slope of the slope in our example is 75%, then when measured in degrees, this value will be 37 degrees.
What factors influence the choice of ramp slope?
Of course, the angle of inclination of the metal roof has a significant impact on the appearance of the building, however, this value is chosen not only for aesthetic reasons. When designing, be sure to take into account:
- wind load in the region. You need to understand that the greater the angle of inclination of the slope, the greater the windage of the roof. Therefore, in the design process, it is necessary to take into account the wind strength characteristic of the region, taking into account possible wind disasters in the area in the form of hurricanes, tornadoes, etc. As a rule, the necessary information on wind load can be found in special reference books.
- Snow load, that is, the weight of the snow "cap" that can cover the roof. It is clear that a thicker layer of snow accumulates on flat roofs than on roofs with steep slopes. If the angle of the roof slope from the metal tile is chosen incorrectly, then the coating may deform under the pressure of the snow mass.
Advice! Naturally, the amount of snow falling in winter is not a constant value and varies from year to year. Therefore, for calculations, average statistical data obtained as a result of many years of collecting information are used. Data on snow loads can be found in reference books.
- When choosing a roof slope from a metal tile, it is also necessary to take into account the fact whether the roof of the house is insulated or not. So, on well-insulated roofs, more snow accumulates than on those through which significant heat losses pass.
Advice! When planning to carry out the insulation of an already operated roof, it is worth finding out whether its slopes have a sufficient slope. The fact is that when installing a heat-insulating layer, the amount of snow accumulating on the coating can increase significantly. And if the slope of the roof is insufficient, then after insulation, deformation of the metal-tiled coating under snow load is possible.
- The choice of the slope of the slope depends not only on the amount of winter precipitation, but also on the amount of rain. So, in areas where there is traditionally a lot of precipitation in the summer, it is recommended to make roofs with a slope of at least 22 degrees.
What is the minimum angle for roof slopes covered with metal tiles?
When choosing a roof structure, it is impossible not to take into account what kind of material is planned to be used to cover the roof. The fact is that for most materials there are restrictions on this parameter.
So, metal tiles should not be used to cover flat roofs. For such structures, other types of roofing should be chosen. The minimum possible slope of the slopes on which it is allowed to lay metal tiles is 14 degrees.
However, in practice, such a small slope for metal roofs is rarely used. Since such flat roofs do not tolerate rain and snow loads. But, it should be noted that roofs with minimal slope slopes are good in areas that are characterized by strong winds and a large number of sunny days, since roofs with a minimum slope are heated less and have a minimum windage.
How to find the golden mean?
Thus, in the design process, it is necessary to choose the optimal angle of inclination of the metal roof so that the roof can withstand both the action of precipitation and wind loads, and does not warm up too much on sunny days.
When solving this problem, one cannot ignore the fact that the larger the slope angle, the greater the consumption of materials, since the roof area increases. Moreover, the consumption of not only metal tiles increases, but also the consumption of materials for the manufacture of rafters, battens and other materials.
Therefore, the choice of slope angle is always a compromise solution, the search for a "golden mean" between the strength of the coating, its cost and the desire to implement certain architectural solutions in the roof structure.
So, the snip does not strictly regulate the slope of the roof from the metal tile. The standards fix the value of only the minimum slope, while the choice of the optimal value of this parameter falls on the shoulders of the designer. In the process of drafting the project, it is necessary to take into account the climatic features of the region, calculate the consumption of material and take into account the wishes of the owners regarding the architectural appearance of the future home.
Roofs made of metal tiles are a practical and popular solution for the construction of private low-rise buildings. This roofing material is characterized by high bearing capacity, resistance to mechanical damage, external environmental factors and heavy loads. The durability and reliability of the finish coating depend not only on quality, these characteristics are influenced by the design of the roof, including the correctly selected minimum slope. In this article, we will tell you how to choose the right slope angle and check it for compliance with SNiP.
The slope of the roof is an important design parameter, which indicates the angle formed by the plane of the floors and the roof slope. This indicator is expressed as a percentage or degrees. It is calculated as the result of dividing the height of the ridge by half the width of the building. The angle of inclination of the slope depends on the technical and operational properties of the material and is regulated by SNiP and the manufacturer's instructions. Depends on it:
- The possibility of using one or another type of roofing.
- The design, composition and section of the elements of the truss frame.
- The ability of the roof to effectively remove rainfall.
- Roofing cost.
- Roofing cake weight.
Note! If the slope of the metal tile roof is increased from 22 degrees to 45 degrees, the slope area will increase by 20%, which will affect the cost of materials (finishing, waterproofing, insulation, wood), as well as the weight of the structure. It is necessary to decide on the optimal angle of inclination during the preparation of the project in order to correctly determine the load on the foundation.
Optimal values
Roofs made of metal tiles are a relatively new constructive solution, therefore the technology of its installation and operation is not clearly regulated by SNiP. Information about what the minimum roof slope should be is provided by the manufacturer, since this indicator directly depends on the technical characteristics of the material itself. This indicator is calculated in accordance with the thickness, bearing capacity and method of laying the roofing.
- According to SNiP, the minimum angle of inclination of a metal roof, if the slope is 6 meters long, must be at least 14 degrees.
- The permissible slope for a metal roof is in the range of 14-45 degrees.
- The optimal angle of inclination, which ensures the effective removal of precipitation with less mercy on the slopes, should be 22 degrees.
Important! The minimum slope of a metal roof, which manufacturers allow, is 11 degrees. Some grades of material can be laid even if the slope is 10 degrees. The reduction in this indicator has made it possible to achieve the use of new, smoother polymers and stronger steel for the production of roofing.
Slope selection
It can be difficult for a non-professional builder to correctly choose the minimum angle of inclination of a metal roof. This indicator, in addition to the requirements of SNiP and manufacturer's recommendations, is influenced by other factors that must also be taken into account. When choosing the steepness of the slope, the following is taken into account:
Please note that the choice of the steepness of the slopes depends on the design of the roof. The optimal angle of inclination of the slopes of a shed roof made of metal is 20-30 degrees, and a gable roof is 20-45 degrees.
Features of roofs with a small slope
The minimum recommended slope angle of a metal roof is 14 degrees, however, experienced craftsmen can lay this type of roofing material with high quality, even if the slope of the slopes is in the range of 10-14 degrees. To increase the reliability of this design and reduce the risk of leaks, the following measures must be taken:
- Increase the frequency of the battens and reduce the pitch between the rafters. To minimize the risk of roof collapse due to intense snow load, it is necessary to strengthen the truss frame of the structure and mount a frequent or continuous crate.
- Increase overlaps. Manufacturers recommend that when installing metal tiles, make a horizontal overlap of 8 cm, and a vertical one of 10-15. To eliminate the possibility of leakage in structures with gentle slopes, you can increase the overlap at the joints of the sheets.
- Isolate joints. To prevent the penetration of melt and rainwater between the joints of the sheets, it is possible to treat the seams with silicone sealant, although this measure has a limited duration.
Experienced craftsmen say that the easiest way to make a reliable metal roof is to follow the manufacturer's recommendations and strictly observe the recommended angle of inclination.
Video instruction
When erecting a roof, you should decide on the angle of its inclination, which will depend not only on the wishes of the developer, the desired contours and design of the house. Roofing material is of great importance for this parameter. When working with metal tiles, the angle will differ from the possible angle allowed when working with slate or metal.
What affects slope
There are several factors that have the greatest influence on the choice of a particular angle of a roof covered with metal tiles. Among them, one can single out:
- wind load;
- snow load;
- roof shape;
- average rainfall.
To calculate this parameter, it is necessary to know exactly the total area of the slope and the wind strength characteristic of a particular region. The area of the slope is easy to calculate by yourself, but you will have to look for the strength of the wind in special reference books. When erecting a roof, it is also necessary to take into account the possible maximum wind load that occurs during cataclysms.
Snow load
This is a value representing the total mass of snow that can be held on the roof until it slides. This parameter is of great importance in the calculation, since the weight of snow can easily deform it if there are errors in the calculations.
For each locality, the handbooks contain certain figures for the average amount of snow, the information in the handbooks has been collected by specialists for more than a decade and is completely true.
thermal insulation
Roof insulation also affects its condition. This is due to the fact that with poor thermal insulation, the roof warms up and the amount of snow on it gradually decreases. After the roof does not warm up and the amount of snow on its surface gradually increases.
If the calculation of the structure was performed without taking into account thermal insulation, then it will probably not withstand the snow load after insulation, this point should be taken into account.
The shape also influences the choice of a particular angle. So, for single-pitched roofs, it is customary to make a slope from 20 0 to 30 0, and for gable roofs from 20 0 to 45 0. This is due to the design features of each type of roof.
To achieve such a good result was possible by reducing the roughness and applying a special surface coating.
The minimum slope of a roof made of metal tiles cannot always be applied. A small slope of a metal roof has both positive and negative points.
Positive moments of a small angle of inclination:
- reduced consumption of roofing material;
- reduced weight;
- ease of installation of weirs.
Negative moments of a small angle:
- the use of reinforced crates;
- high requirements for load capacity due to the likelihood of accumulation of large amounts of snow;
- increased requirements for the tightness of all joints due to the small angle of incidence of water during rain;
- the inability to create attics or large attics.
Positive aspects of a large slope of the roof:
- the possibility of moisture getting into the joints of the roofing material during rain is almost completely excluded. This is due to the large angle of incidence of drops;
- reduced, and at angles from 45 0 practically absent snow load. No need to equip a snow retention system;
- the possibility of using simple fasteners, such as screws and nails;
- the possibility of creating attics and rooms in the attic.
Negative moments of a large slope:
- high consumption of material, both roofing and truss systems;
- heavy weight of the roof;
- high wind load due to the large windage of the roof;
- the complexity of water disposal, this is due to the large area on which water accumulates.
The best option is to use the average angle of the roof slope, which allows you to get the best performance. Calculating the right angle always comes down to finding a compromise between the strength of the roof and possible architectural refinements.
The angle of inclination of any roof significantly affects its reliability and tightness. The minimum slope of a roof made of metal tiles, according to the requirements of SNiP, must be in the range of permissible values. Failure to comply with this rule may lead to a number of irreparable consequences. Roofing made of metal tiles has a number of characteristic features associated primarily with the specifics of this material.
Metal tile as a roofing material is very popular. It can be used for arranging roofs with various geometric shapes. It does not exert a large load on the structure. Installation of a metal tile is absolutely not difficult and within the power of any roofer. A diverse range of colors of this material is very convenient when creating any design. When choosing it, it is necessary to take into account the slope of the roof.
The concept of slope and its calculation
The slope is directly the angle of the roof in relation to the level of the horizon. When carrying out roofing work is a fairly significant factor. The angle of inclination of any roof is calculated as follows. The calculation can be considered on the example of a right triangle. For example: the width of the building is 10 meters, the height of the gable in the ridge is 3 meters.
Side c - ½ width. So a=3, c=4. From the secondary school program tg A=а/с. Total tgA=0.75. We look at the table of tangents on the Internet. The angle is 37 degrees. The SNiP directly prescribes the values \u200b\u200bof the minimum angle of inclination of the roof, taking into account the type of material and climatic conditions. Given the requirements of SNiP, the minimum roof slope, with a slope length of 6 meters, is 14 degrees.
What affects the choice of slope angle
The slope of any roof is designed to prevent the accumulation of snow or rainwater on the roof. There are no unified slope angles. Many factors influence the minimum slope. They must be taken into account when designing a structure. This is first of all:- type of truss system;
- climatic features;
- roof configuration;
- the purpose of the attic space;
- the appearance of the building;
- financial opportunities to perform roofing work.
climatic factors
The angle of inclination of the slope is chosen, as a rule, taking into account the climatic conditions of the area where construction is underway. Namely, depending on the amount of precipitation and wind speed in the area.- The wind load is calculated taking into account the surface area of the roof. At the same time, it will be useful to foresee the strength of the wind and the possibility of cataclysms associated with it. Too steep a roof, as a rule, increases windage and may not withstand strong wind loads. Experts calculated that with a roof slope of 45 degrees, the wind force on it is 5 times higher than the wind load acting on a roof with a slope of 11 degrees. For the installation of such a roof, more material will be needed, which will undoubtedly hit the owner's pocket. If the slope is too slight, a gust of wind can demolish the roofing material.
- In winter, snow accumulates directly on the roof slopes. At a certain slope, it slides down. If it is small, then the roof will have to be cleaned to avoid damage to the truss system. Taking into account SNiP, the roof projection must be carried out with a mandatory margin of safety, in order to avoid possible deformation of the metal tile. The steeper the angle of the roof, the less opportunity for snow layers to stay on it. But at the same time, the weight of the roof will be greater due to the increase in the amount of roofing material. With a large angle, the problem of installing a multi-tiered drainage system also arises. The difficulty is that there is a fairly large section of the roof per unit length of the sewer pipe. Since the water drains very quickly, it is more difficult to choose a pipe with the desired cross section. The only way out is to install a drainage system in several tiers. And this is an additional financial cost.
- A significant factor influencing the choice of the minimum angle of inclination of the slope is the quality of the heating of the house and its thermal insulation. If the thermal insulation of the roof is of poor quality, then snow does not accumulate on the slopes, as it will thaw and slide down. However, with good thermal insulation, accumulations of snow cannot be avoided.
The minimum slope requires the installation of additional waterproofing to prevent moisture penetration. To do this, a layer of silicone sealant is applied to the joints.Even in advance, when purchasing a metal tile, you should pay especially close attention to the recommendations of its manufacturer. As a rule, he recommends designing a slope angle of 12 degrees. There is a more durable material with the possibility of mounting and at an angle of 11 degrees. Such a metal tile is made with a smoother surface, which contributes to good sliding. If you do not take into account the recommendations of the manufacturer and perform a roof with a lower angle of inclination of the slope, then as a result of heavy snowfall, there may be a risk of roof collapse. The minimum slope angle is typical for regions with a warmer climate, where the amount of precipitation in the form of snow and rain is minimal. At the same time, the roof perfectly resists large wind loads.
This design is especially relevant for areas in which the number of sunny days per year reaches a maximum. Since the roof area with such a slope is smaller, then heating it in the summer creates less discomfort for the residents of this house. Moreover, with a smaller roof area, a smaller amount of metal tiles will be consumed. And this is a pretty good option to save the budget. Since there are no strict requirements in SNiP as to what the minimum slope of a metal tile roof should actually be, then it must be chosen according to the recommendations of the manufacturer of this material. As a rule, its value varies between 11 and 15 degrees. Its increase entails additional consumption of metal tiles. Excessive reduction requires additional waterproofing and installation of additional structures for reinforcement. Therefore, the optimal solution to this problem is to choose the average value. We recommend watching the video
