The reliability and comfort of the operation of the building largely depends on how competently and efficiently the construction of its roof is carried out, including how correctly the optimal angle of inclination of the roof is chosen, which will be discussed in this article.
The slope of the roof is related to the material of the roof
The slope of the roof is taken depending on the design of the roof and facade of the building, as well as on the material chosen for roofing. In addition, the choice of the angle of inclination may be affected by the climatic conditions of the region in which construction is underway.
In areas where there is frequent precipitation, and heavy snowfall occurs in winter, a large roof slope of 45 to 60 degrees is usually chosen.
This reduces the load of snow cover on the roofing system, since large masses of snow will not accumulate on the roof, but will slide from it to the ground under their own weight.
If strong winds are typical for the region where construction is being carried out, then it is advisable to choose the minimum angle of inclination of the roof, which reduces the so-called windage of the roofing material.
To do this, usually choose a value from the range from 9 to 20 degrees.
Therefore, the most universal solution is to choose a value between the two specified ranges, so the most common is a roof slope of 20-45 degrees.
This slope value also allows the use of most modern roofing materials during construction, for example, you can build do-it-yourself corrugated roof.
Roof types
The most common form for utility and utility buildings is a shed roof, which does not offer anything original in terms of design, but attracts with low cost and ease of construction: the design of such a roof essentially consists of walls of various heights and roofing material laid on them.
The slope of the roof in this case is mainly from 9 to 25 degrees, since most often such roofs are covered with corrugated board. The absence of an attic under the roof allows you to choose a rather small angle of inclination, but you should not forget about the organization of ventilation of the space under the roof.
The most common type of roof is gable roof, the design of which consists of two planes (slopes) connected along one line (horse).
The walls that are the ends of the building are called gables, they can be provided with doors that allow you to use the attic or make minor repairs, as well as acting as ventilation holes (air vents).
In modern construction, hip roofs are the most popular, allowing you to perform a truly unique roof design.
The angle of the roof slope here can be almost anything, depending on the taste and imagination of the person who designed the roof structure.
Most often built hip hipped roof, and two slopes are made in the form of triangles.
Useful: in the construction of hip roofs, there are practically no restrictions on the material used to cover the roof. The rather complex design of such a roof is compensated by the very spectacular appearance of the roof, and the more complex the general plan of the house, the more original the hip roof can turn out to be.
A slightly more complicated version of the hip roof is the mansard roof, which is erected in order to use the attic space as a living space, which makes high-quality insulation and vapor barrier of the roof mandatory.
The space that makes up the attic floor is formed by a system of broken slopes and rather high angles of inclination. In addition, dormer windows should be equipped here, which can also serve as an additional decoration of the roof, and it is also necessary to insolate the room.
The optimal roof slope depends not only on the design decisions of the developer, but also on the weather conditions of the region where the construction is being carried out, which should also be taken into account when choosing the best roof design.
An important role in determining the slope is also played by the roofing material, which imposes certain requirements on the roof structure.
Influence of climatic features of the construction region
If the area where the construction takes place is characterized by frequent strong winds, the optimal slope of the roof should be minimal, since large values of the angle will cause the roof to “sail”, leading to an increased load on the supporting structure, which can cause damage and destruction at the slightest miscalculation in its project.
The construction of a reinforced supporting structure, taking into account strong winds, requires much more serious financial costs.
Construction in a region that is characterized by frequent heavy snowfalls requires an increase in the angle of inclination, which does not allow significant snow masses to linger on the roof: they will roll down the roof to the ground under the influence of their own weight, without creating dangerous loads for the roofing material.
In regions where sunny days predominate, flat roofs with a minimal heated surface are the most preferred option.
Also, roofs in such areas are often covered with gravel, since dark rolled materials can also heat up significantly under the influence of the sun's rays. In this case, even a flat roof should have a slight slope angle (from 2 to 5 degrees), leading in the direction of the rainfall hole.
The choice of roof slope depending on the material
When choosing a material for roofing, you should carefully study the characteristics of the proposed materials, as well as their recommendations, which will help you choose a material that will last a long time and reliably.
You should learn more about how to determine the minimum slope angle for various roofing materials:
- For type-setting piece materials, such as slate and tiles, the minimum angle is 22 degrees, which helps prevent moisture from accumulating at the joints and seeping into the roof;
- For roll materials, the minimum angle of inclination is selected depending on the number of layers laid: from 2 to 5 degrees with a three-layer coating, up to 15 degrees - with a two-layer coating;
- The minimum angle of inclination of the roof from corrugated board, according to the recommendations of the manufacturers, is 12 degrees; at small angles, joints should be additionally glued with sealants;
- When covering the roof with metal tiles, the minimum angle is 14 degrees;
- When covered with ondulin - 6 degrees;
- For soft tiles, the minimum slope angle is 11 degrees, while a prerequisite is the installation of a continuous crate, regardless of the selected angle;
- Membrane roofing can be used with roofs of any configuration, so their minimum slope is from 2 to 5 degrees.
When choosing the angle of inclination, it is also necessary to correctly calculate the bearing capacity of the roof structure - it must be able to withstand any loads and external influences that are possible in a given area.
This takes into account the constant load, which consists of the weight of the roof and its structures, and the temporary load, which occurs as a result of snowfall or wind blows.
Important: the type of lathing and its pitch also depends on the angle of the roof slope for many materials. It is recommended for small angles of inclination to perform either a continuous crate or in increments of 350 to 450 millimeters.
When erecting a flat roof, a number of requirements must also be met, one of which is the organization of water drainage from the roof using a slope system.
In the case of a large roof area, an additional emergency drain is often installed in case the water flow exceeds the capacity of the main drainage system.
Given the rather serious prices for materials used in construction and repair, the choice of roofing material should be done carefully and thoughtfully, evaluating all the positive and negative characteristics of the products offered and choosing the material that can provide the greatest reliability at the lowest price.
The construction of the roof should also be done very seriously, since a small mistake in choosing the angle of its inclination can lead to unpleasant consequences not only in the form of unplanned repairs, but also in the form of harm to the health and life of people living in the building.
An example of calculating the angle of the roof
The slope angle of the roof is calculated taking into account the climate of the area where the house is being built, as well as the selected roofing material: with a large amount of precipitation, the angle is increased, and with strong winds, it is reduced, and the most effective in terms of material consumption are roof angles from 10 to 60 degrees.
The values of the height of the roof ridge and the rise of the rafters are determined either using a square, or calculated, for which the span width is divided in half and multiplied by the appropriate coefficient from the table below.
For example, with a house width of 10 meters and a roof slope of 25º, the height to which the rafters rise is calculated by multiplying half the width of the house (5 m) by a coefficient from the table equal to 0.47, and we get 2.35 - exactly the rafters must be raised to this height.
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