I have to isolate my attic to arrange them. I have a house in millstone with between the rafters a thickness of a few cm of plaster supported by wooden rods (insulation of yesteryear !!). To isolate I must drop this plaster and access my tiles or leave it and isolate from above. Which thermal and phonic insulation insulator knowing that I can not do too thick (about 10 cm). I saw the product Isomat + (wood fiber and hemp) and a new thin insulation "Skytech" as well as Fermacell plates to close? I thought to put these three there but how? Is thin insulation useful? Should I put a steamer?
What you describe as isolation of yesteryear is not one. It is only a coating of plaster applied on a lattice of wood. This is called a "bacula". Start by removing it to start on a good basis. The space available for insulation being small, it is difficult to implement all the insulation you have considered. The idea of putting the thin reflective product on the attic side is good for getting airtight more than for insulating. It can act as a vapor barrier. This is the so-called global insulation solution developed by KDB. That being so, with only 10 cm of available, you will not be able to obtain isolation with a conventional fibrous insulation considering the necessary air gap (2 cm) and the thickness of the thin product (2.5 cm ), which would leave you only 5.5 cm of insulation. More suitable solutions exist: the projection of polyurethane foam will provide you with good insulation while ensuring a total absence of thermal bridges. Indeed, with 12 cm thick (covering the rafters) you will get an R of 4.8 (0.12 / 0.025 = ± R 4.8). Attention to choose a professional for the implementation of this technique (you will find all the necessary information on the site of EUROPISO for example, or on the sites of EFISOL and BI-COMPOSITE).
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