How To Insulate A Flat Roof Attic

Then install r 30 fiberglass batts between the rafters.

How to insulate a flat roof attic.

This technique involves placing insulation directly between the ceiling of the upper floor and the attic floor which prevents heat from penetrating the attic. In either case you will need to follow the general steps below to insulate your garage roof. However if you have a cathedral style garage roof you will need a scaffolding to get into the upper areas of the roof. With flat roof insulation a vapor barrier should sit between the joists and ceiling panels and the insulation on top.

This old house general contractor tom silva and host kevin o connor demonstrate the proper way to insulate an 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. With a warm roof the usual process is to split the insulation into two layers. A layer of rigid insulation board can be added either on top of the roof s weatherproof layer or directly on top of the timber roof surface with a new weatherproof layer on top of the insulation.

With this method only the attic floor is insulated. The simplest and cheapest solution for attic insulation is the so called cold attic. It should be installed on tapered 2x furring strips in order to slope the surface of the roof to drains. See below for a shopping list and tools.

Rigid foam panels are available in thickness. 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. 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. If you have a flat garage roof and an attic above you can install the garage insulation from below using a standard ladder.

A flat roof should preferably be insulated from above.