Attic Insulation Rafters Or Joists

The technically correct approach depends on a number of factors.

Attic insulation rafters or joists.

Unlike solid insulation products that require careful measurement cutting and fitting spray foam can cover even the most uneven surface instantly. Joists are traditionally made from timber. 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. In unfinished attic spaces insulate between and over the floor joists to seal off living spaces below.

1a attic access door. Insulating attic floors unfinished or uninsulated attics need a layer of protection against air migration. If the air distribution is in the attic space then consider insulating the rafters to move the distribution into the conditioned space. Standard joist spacing for the installation of attic flooring materials is 16 inches on center oc meaning the distance from the center of one joist to the center of the next joist is 16 inches.

Either batting or blown insulation works in attics. For a correct approach an inner roof lining is required. They are nominally 2 inches thick actual width usually 1 1 2 inches and come in a variety of widths from 8 to 12 inches. When unrolled batting assumes its loft or thickness.

Joists are the parallel horizontal beams that run across an open space joining opposite walls in a building to support both the ceiling below and the floor above. Install batting between the attic s floor joists. Whether or not there is an inner roof lining and the total thickness of the roof structure. Batting comes in rolls and is sized to fit between rafters or joists.

You can use rigid foam panels or do as tom silva does with nearly all houses these days. Polyurethane or polystyrene spray foams can provide thorough coverage to roof rafters and attic walls in much less time than is needed for other materials. Spray foam insulation in the attic floor non vented attic spaces in this application considered the most effective by most of the spf industry the foam is sprayed directly to the underside of the roof between the joists down around the rim and into the soffit areas on the gable wall ends and effectively sealing off and insulating the entire attic space from any air infiltration.