Attic Insulation Rafters Or Joists

The ceiling joist system is typically constructed from substantial two by tens or larger dimension boards but some older homes have smaller joists.

Attic insulation rafters or joists.

In finished attic rooms with or without dormer insulate 2a between the studs of knee walls 2b between the studs and rafters of exterior walls and roof 2c and ceilings with cold spaces above. 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. If you decide on mineral wool such as glass wool or rock wool you will need to put down a damp proof membrane. 2d extend insulation into joist space to reduce air flows.

You can use rigid foam panels or do as tom silva does with nearly all houses these days. Insulating attic floors unfinished or uninsulated attics need a layer of protection against air migration. 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. Unless expressly built so an attic s joists are meant for carrying the load of the ceiling below and related elements collectively known as the dead load.

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. The ceiling load may include items like drywall ducts recessed lights bathroom fans and attic insulation. Install batting between the attic s floor joists. In practical terms you can choose between mineral wool or insulation boards.

Hire a pro to install spray foam insulation. Even rafter insulation can encourage damp as it stops draughts and reduces natural ventilation. 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. The batting material must be faced and.

Unlike solid insulation products that require careful measurement cutting and fitting spray foam can cover even the most uneven surface instantly. Insulation between the joists will make your attic much colder so this could worsen your damp problem. If you want to install standard r 38 insulation.