I recently purchased a house, and it has an attic conversion. Once winter came along we found out that there is no insulation between the roof and the plasterboard.

Does anyone know of a way I can get it insulated without pulling down all the plasterboard?

1 Answer 1


The most common method would be to blow in high density cellulose between the rafters. This method requires that a small hole (1 to 2 inches each) be drilled in sheetrock, at the top and bottom of each bay. After the insulation is blown in, repair the holes or use plugs to cover the holes. Foam can also be used, but is about 4X the cost of cellulose and very tricky to install without bowing or damaging the rock.

Regardless if you use cellulose or foam, this is not typically a DIY project. Many insulation contractors offer this service and have the right tools to assure a good fill.

  • 1
    How can the contractors assure that the soffit to ridge venting is maintained when they just blow in the insulation as described?
    – Michael Karas
    Commented Apr 27, 2013 at 9:42
  • If the cavities are vented and covered directly with sheetrock, then they cannot be insulated. This situation is a no no!!! Soffit to ridge venting should not be done in a closed cavity. Commented Apr 27, 2013 at 9:56
  • Should and 'is' are two different things. As a conversion, there's a fair chance a functional venting system is still in place. Any vents to rafter cavities should be closed off prior to insulation. If there are any remaining enclosed non-habitable attic spaces, proper ventilation must be maintained to such areas. The problem with retrofit blow-in projects is there is typically not any kind of viable vapor barrier. Not an issue with foam, but for cellulose.
    – bcworkz
    Commented Apr 27, 2013 at 18:20

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