Should You Insulate Between Roof Rafters

If you re considering turning your attic into conditioned storage or living space it s worth changing tactics to insulate between the rafters and wall joists instead of the floor.

Should you insulate between roof rafters.

If your attic is going to be converted into livable space then you will need to insulate the roof rafters. The rafters are joined together by a horizontal ridge board at the top and tied together by ceiling joists at the bottom. Make sure it is flush against the wood as also a 1 inch gap can create a 20 percent heating loss. You can use rigid foam panels or do as tom silva does with nearly all houses these days.

On new build or replacement pitched roofs the ideal build up would be insulation fitted over and then between the rafters giving a big boost for airtightness image credit. The will hold open an air gap of approximately 1 inch to allow airflow past a layer of insulation. For rolled insulation location it in between roof covering rafters. Install ventilation baffles into the space between the rafters before you install the insulation usually by stapling into place.

You can add insulation to the floor. Usually you will certainly fill the insulation blower with the insulation and blow it between the attic floor joists. Attic moisture problems are often the result of heated air from the living space rising up into the attic which is not heated. Insulating the rafter space will give you a warm loft.

Insulating between rafters will do no good because the attic should be ventilated and the rafter insulation would be between two unheated spaces. Hire a pro to install spray foam insulation. In order to avoid damage to the roof deck you should insulate ceilings to create an air barrier between the living space and an unfinished attic or airspace underneath the roof deck. The ones i ve used are made of styrofoam and iirc they cost around 2.

The current trend is for a warm roof where insulation is installed between the rafters thereby keeping the roof timbers warm. This means insulating between or below the sloping beams that form the construction and support a sloping roof. You can also add rigid foam insulation under the rafters which adds r value and eliminates thermal bridging through wood rafters.