During the construction of a house, cottage or any other premises, it is necessary to provide, think over and correctly design the ventilation system of the building as a whole and all its parts in particular. No exception and roof ventilation, which is actually a very important stage in the construction of the roof.
It is not worth proving something that a priori does not require proof: the roof is the most important part of your home. It is the roof that takes the blow from all natural adversities and atmospheric phenomena.
Roof and roof space ventilation
Roof your home is subject to maximum impact from the outside by natural forces, but you also need to know and understand that the roof can collapse not only from the outside, but also from the inside.
And in this case, the ventilation of the under-roof space will preserve the inner surface of the roof and ensure the safety of the roof of your house.
Ventilation is necessary due to the high probability of moisture condensation on the internal surfaces of the roofing. This is inevitable if there is a significant temperature difference between the outer and inner sides of the roof..
Your attention!
One of the ways to prevent moisture condensation is to install hydro and vapor barriers under the crate.
These fabric membranes, on the one hand, prevent the penetration of moisture from the warmer attic air to the inner surface of the roof.
And on the other hand, an air gap is left under the roofing material, in which air circulates.
Roof ventilation system should perform several basic functions:
- removal of vapors penetrating into the attic or attic from the living quarters of the lower floors;
- prevention of condensation of moisture from the attic air on the cold inner surface of the roofing;
- temperature stabilization along the entire length of the slopes. This will help to avoid the formation of ice and icicles on the eaves and overhangs due to the melting of snow over the heated sections of the slopes and their freezing on the cold parts of the roof;
- reducing the effects of solar heat on the roof.Properly organized ventilation will reduce the heating of the under-roof space, reduce the air temperature in the premises and reduce the cost of air conditioning the entire building.
The easiest way to organize roof ventilation under the roof of the house in attic spaces. Significant volumes of air, freely moving in the attic space, provide good ventilation of the roofing material and the entire attic.
Vents under the cornices, in the ridges and in the gables provide ventilation of the attic with outside air and equalization of temperatures on the inner and outer surfaces of the roof. At the same time, the circulation of air masses under the roof occurs due to natural convection - warm air heated by the ceiling of residential premises rises under the roof and exits through the ridge vents.
Cold air from the street is drawn into the attic through the cornice vents. The temperature difference between the outer and inner surfaces remains, but is insufficient for moisture condensation on the roof.
Advice!
In general, pitched roofs of a simple shape require the same number of vents at the bottom and top of the slopes.
For normal air circulation, the total area of these holes should be equal to approximately one three hundredth of the total area of \u200b\u200bthe roof slope.
Somewhat more difficult under-roof ventilation is organized on mansard roofs. It is more difficult because free air circulation in the under-roof space is impossible due to the fact that almost all the space under the roof is occupied by the attic.
In general, mansard roofs are divided into:
- ventilated (with ventilation gaps);
- non-ventilated (respectively, without ventilation gaps).
Ventilation of mansard roofs is organized directly under the roof covering between the roof and layers of hydro- and thermal insulation.
A ventilated roof can have three ventilation circuits:
- under-roof ventilation, providing air circulation directly under the roofing. The advantage of such a scheme is its ability to guarantee reliable ventilation, no matter how complex the shape of the slopes of the roof.
This is how mansard roofs are ventilated; - volume ventilation between the insulation and waterproofing. Such ventilation should be calculated so that the occurrence of "stagnant" zones is excluded;
- ventilation of the entire volume of the attic space. Such ventilation, as a rule, is an integral part of the entire ventilation system of the house and should be provided for at the design stage of the building.
Technically, it is convenient to organize roof ventilation using devices such as a passage element and a roof valve. Pass-through elements serve for the passage of ventilation pipes through the roofing pie.
Roof valves are a ready-made ventilation vent, covered from precipitation and equipped with an apron to organize waterproofing of the tie-in into the roof. Each manufacturer has valves with aprons that allow inserting into the roof with any type of roofing.
Also, roof valves are equipped with a protective mesh to prevent rodents and birds from entering the under-roof space.
Roof ventilation must perform its functions at any time of the year, even if the roof is covered with snow. Therefore, it is recommended to combine the use of roof valves with the installation of ventilation pipes with a height of 30-50 cm.
Forced ventilation
In addition to natural ventilation of the under-roof space, there is also forced ventilation.
As a rule, for the organization of forced ventilation, a roof fan is installed in the upper ventilation vent, which ensures the extraction of warm air from under the roof covering..
The use of fans to create a normal hydrobalance under the roof is justified if it is not possible to create the required number of vents for natural ventilation. And also in the construction of flat roofs, where natural convection is not enough for thermoregulation of the roofing.
Your attention!
It is recommended to install a roof fan at the stage of roof construction. Embedding devices into a finished roof is much more difficult and expensive.
In addition, if you are installing a fan due to excessive moisture in the under-roof space after the fact, then you will need a high-powered device to dry the hydro- and thermal insulation that has already accumulated moisture.
Roof fans have one significant drawback - the need to supply power to them. On the other hand, when installing forced ventilation, you can get by with fewer vents in the roof, which increases its overall reliability.
We hope this article has shown that properly organized roof ventilation will keep wooden roof structures from rotting, metal ones from corrosion and ensure roof operation for a long time.
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