How To Insulate A Flat Roof Attic

If you have a flat garage roof and an attic above you can install the garage insulation from below using a standard ladder.

How to insulate a flat roof attic. Use rigid foam insulation panels on your flat roof before applying the final roof covering or inside the house before adding sheetrock or paneling. Sealing bypasses bypasses are anywhere that there is a break in the insulation. This technique involves placing insulation directly between the ceiling of the upper floor and the attic floor which prevents heat from penetrating the attic. However if you have a cathedral style garage roof you will need a scaffolding to get into the upper areas of the roof.

With a warm roof the usual process is to split the insulation into two layers. This old house general contractor tom silva and host kevin o connor demonstrate the proper way to insulate an attic. This is best done when the roof covering needs replacing anyway. With this method only the attic floor is insulated.

If 180mm is to be installed then 100mm board might be introduced between the rafters there has to be a minimum 25mm air gap between the insulation and the underside of the tiles or slates with an 80mm board running across the rafters. A flat roof should preferably be insulated from above. The materials used to insulate under the roof include batts of mineral or glass wool insulation held in place by battens of wood attached to and across the rafters. With flat roof insulation a vapor barrier should sit between the joists and ceiling panels and the insulation on top.

See below for a shopping list and tools. It should be installed on tapered 2x furring strips in order to slope the surface of the roof to drains. Then install r 30 fiberglass batts between the rafters. Framing this out and buying 30 r fiberglass insulation will cost you about 50 more than just buying 5 inches of polyiso equivalent of 30 r.

In either case you will need to follow the general steps below to insulate your garage roof.