Roof insulation - what materials to choose?
Competent selection of soundproof material requires basic knowledge in the field of building acoustics. If you simply listen to other people's advice, without understanding the essence of the process of absorbing sound waves, then there is no guarantee of an effective solution to the problem of noise isolation. In order to choose the right material for soundproofing, you need to pay attention to two main indicators:
- sound absorption index
- dynamic modulus of elasticity
The sound absorption index shows how much of the total amount of radiated sound energy the material absorbed, that is, how effectively it worked as a soundproofing device. This value is evaluated in laboratory tests in the audio frequency range from 125 to 4000 Hz - the main noise spectrum in residential buildings.
Good sound insulation of the roof is possible only with the use of materials with this parameter not lower than 0.6. For example, for wood, the sound absorption index is 0.07-0.15, and for mineral wool - from 0.7 to 0.9.Polyfoam, in spite of good thermal insulation qualities, in this series looks rather modest - 0,15-0,25.Therefore, it can not be recommended for noise insulation of the roof.
The dynamic modulus of elasticity is measured in MPa and characterizes the elastic properties of the material. The higher it is, the worse the material absorbs sound. This is understandable, since dense material reflects sound better than loose. For example, comparing plates of basalt or fiberglass with their modulus of elasticity 0.045-0.25 with a foam, in which this figure is from 0.5 to 1.3, one can make an unambiguous conclusion in favor of fibrous materials.
The construction of sound insulation of the roof of the house
Having selected a good soundproof material, we simultaneously solve the problem of thermal insulation, as any loose and fibrous material keeps the heat well. However, this is not the point at issue. After buying a quality material, the next step is to select the optimal design for installation.
The main factors directly influencing the noise insulation of the roof of the house , are:
- Good acoustic isolation at the points of abutment to the rafters and the inner lining of the attic;
- Clearance between soundproofing material and roofing structure;
Accordingly, the entire structure of the anti-noise barrier must be constructed in accordance with these two requirements.
Installation of sound insulation of metal tile
The insulating material is usually installed in the spaces between the rafters. Above it borders on the crate, so the requirement to ensure a gap between metal and soundproofing is performed automatically.
However, the noise insulation of the metal tile will not work at its fullest if we do not eliminate the influence of "acoustic bridges" - rafters, which transmit the roof vibrations to the roofing of the attic walls. As a result, we get a large resonating surface, and the insulation can not reduce its vibration.
This problem can be solved by an insulating gasket made of any elastic material, from ordinary felt to polyethylene foam. We will install insulating strips along the rafters and plasterboard, lining or OSB slabs that the attic is being lined with, will not transmit external noise to the house.
In conclusion, I want to say about another factor, which does not directly affect the noise insulation of the roof of the house, but which should be taken into account at the stage of roofing works.
Poor installation of sheets leads to their deformation due to temperature, wind and precipitation, causing rattling and creaking. Therefore, to combat this problem should be, starting with the first samorez, twisted in the crate.
