The Content Of The Article:

We have the project to isolate the attics lost by the floor. About 80 m². There is already a floor insulation in glass wool but not thick enough. We want insulation by blowing flakes. By cons for which insulator opt: rock wool, cellulose wadding or other. Which material will be the most effective at the level of insulation but also at the fire safety level? Should we provide a vapor barrier?
We are in Ile de France, what thickness of insulation does it take?

I still consider it preferable to remove the old insulation.
Cellulose wadding is a good insulator, supposed to offer a better summer comfort. Its performance is almost equivalent to that of rock wool but its implementation requires a perfect seal of the cover because it is very sensitive to moisture.
Mineral wools (glass or rock) offer better resistance to fire and moisture. They have proven themselves.
Whatever the chosen product, the guarantee of a technical performance depends entirely on the implementation which will have to be carried out in the rules of the Art.
With a blown wool, an airtight membrane should be placed on the ground.
To obtain an R = 10 in accordance with the 2012 RT in top of lost, an average thickness of 460 mm of insulation will be necessary.

On the same topic

  • Questions answers
    • Can a floor be made of loose insulation?
  • DIY tips
    • Cellulose wadding insulation in semi-rigid panels
    • Insulation of floors and floors
    • Insulate the floor of semi-convertible attic
    • Insulate the attic floor with loose wool
    • Insulate a ceiling with glass wool placed between the joists
    • Insulation of the ceiling from the attic floor (with expanded mica, or Vermiculite)

This may interest you

Video Instruction: How to Beef Up Attic Insulation - This Old House