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 quality project in advance. Also, do not forget about the materials, which certainly should not be saved so that you do not have to overpay, as in one well-known saying. They should not only meet 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, in addition to this, it is necessary to take into account the slope of flat roofs. This is as important a stage as the selection and calculation of rafters, insulation.
The operational efficiency of the roof is directly dependent on its inclination. And when calculating this parameter, it is necessary to take into account the region of residence, for which purpose the attic and the roofing materials used are being built.
The advantage of flat roofs
Despite the fact that during the construction of private houses flat roofs are made in isolated cases, they have several advantages. And above all, the low cost of work, since less building material is spent in comparison with the construction of pitched roofs. Their installation is not as complicated 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 small slope of flat roofs will allow you to install any equipment, often air conditioners.
The invaluable advantages of a flat roof make it popular not only abroad, but also in Russia. This is contrary to the seemingly unattractive design. Currently, the inverse type of roof is gaining popularity. But this is not about that. First you need to understand whether you need to do a bias.
The need for a slope of flat roofs
Many buildings are made with a flat roof. 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 talk of any puddles, reality shows the opposite. Various natural factors are used:
- exposure to wind;
- solar radiation;
- precipitation;
- temperature changes and others.
As a result of all this, over time, the roof begins to deform. Accordingly, places are formed in which moisture and dirt will begin to accumulate, inflated by the wind. In the presence of at least some slope of flat roofs, this probability is minimal.
What are the implications?
It would seem that the worst could happen because of the water? Everyone knows that it is the basis of life of all things 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, its chemical composition contains a variety of substances. Here they are adversely affecting the roofing material. And in winter, the liquid generally goes into a solid state - this is where a powerful crushing force is hidden! And if there is at least some minimal slope of the flat roof - the worst can be avoided.
Many noticed how vegetation blooms on the roofs - the wind, along with the sun and water, do their job. And as you know, the root system of plants is a fairly strong organ that can destroy almost any durable material. Over time, of course, but it does not get any easier.
Grade designation
All parameters of a flat roof, including the slope, are regulated by document SP 17.13330 SNiP II-26-76, which is called the "Roof Code. The roofs" (translated from the English the roofs - roofs). This document applies to the design of roofs from virtually any material:
- bituminous and rolled;
- slate
- from tiles;
- profiled, galvanized, steel, made of copper sheet;
- aluminum, zinc-titanium and other similar designs.
The slope of the slope relative to the level of the horizon, called the slope of the roof, can be indicated differently. In practice, its value in degrees is usually indicated, which is more convenient.
However, in the documentation you can find the writing of the slope of the flat roof in percent. There are significant differences between these designations. 1 degree is equal to 1.7%. 31 degrees will be already 60%. In this regard, it is important to know such ratios so as not to be mistaken in the calculations.
What should i know about?
When making a roof slope, it is worthwhile to clearly understand the purpose of this process. Perhaps you need protection from the harmful effects of external environmental factors. In some cases, the roof slope depends on the architectural features of the surrounding buildings, and there is no desire to stand out from their background. The material used is also important, since each has its own indicators that are acceptable during installation.
But special attention should be paid to wind loads. With a maximum slope of the flat roof, the roof will serve as a sail, which is not good. On the other hand, precipitation will not accumulate on such a roof. Neither a drop of rain nor snow will linger on such a surface for a long time.
The scope of the attic also matters. To equip the attic, steep inclines are best avoided. And in any case, financial opportunities also make adjustments. If necessary, erect a roof at an angle of 45 or more degrees, do not avoid an increase in spending on roofing materials. Depending on this, the value of the slope angle is selected.
The dependence of the roof material on the degree of slope
In addition to the fact that 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 slope angle is small, then thermal insulation will be required more, since moisture from the gently sloping roof is not in a hurry to leave.
To equip the roof using different materials. This slate (asbestos-cement, cellulose-bitumen sheets), metal, roofing felt and other options. Consider the most common.
Metal tile
This material has considerable weight when compared with other analogues. 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 should be as low as possible.
If you choose too large a slope of the flat roof, it will swell, which will entail an increase in the load on the supporting structure. As a result, the roof may collapse prematurely.
As a rule, for such a roof, the optimum slope angle will be a value of 27 degrees. Then the roof will reliably protect the house from moisture. The minimum value is 14 degrees. When using soft material, the slope can be reduced to 11 degrees. Only the roof in this case needs an additional crate.
Decking
This material is considered the most popular for roof construction. It is lightweight, but at the same time strong enough to meet many of the requirements of property owners. Installation is not difficult, 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 from corrugated board with an angle of at least 8 degrees and with a pitch of 40 cm (grade H-60, H-75). However, material of grades S-8, S-10, S-20 and S-21 allows a slope angle of not more than 15 degrees. The step of the crate in this case 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 utility or industrial buildings. In residential buildings, the minimum threshold is 10 °. But as for the maximum slope, there are no special restrictions. For this material, you can build roofs at least with a slope of 70 °, at least a large angle.
The optimal value of the slope of the flat roof (the norms will be met at the same time) will be 20 °, which will allow snow and water to leave in a timely manner. Then you will not need very large investments, and the roof can be laid in two layers. Due to this, the risk of leakage of moisture through the fasteners will be minimized.
Soft roof
Here, too, there are their own values of the angle of inclination, if we take into account rolled roofing materials (such as roofing material, ondulin) or modern polymer (membrane) products. As a rule, the value of the angle of inclination lies in the range of 2-15 °. More accurate indicators depend on the number of stacked layers.
If necessary, the flooring of a two-layer roof, the angle value is 13-15 °. The slope of the three-layer coating will be already smaller - 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 chooses a flat roof slope; Construction Norms and Regulations (construction norms and rules) are not violated. However, it should be borne in mind that the roof must withstand loads that are not only temporary, but also permanent. The first include precipitation depending on the season and their weight, gusts of wind. The second is the mass of the roofing material itself, which acts on the supporting structure.