Attic Insulation Rafters Or Joists

In practical terms you can choose between mineral wool or insulation boards.

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. 2d extend insulation into joist space to reduce air flows. Even rafter insulation can encourage damp as it stops draughts and reduces natural ventilation. The batting material must be faced and.

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. Hire a pro to install spray foam insulation. 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.

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. 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 want to install standard r 38 insulation. If you decide on mineral wool such as glass wool or rock wool you will need to put down a damp proof membrane.

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. Unlike solid insulation products that require careful measurement cutting and fitting spray foam can cover even the most uneven surface instantly. So insulating the floor of the attic is not only the best solution but it is also the simplest and cheapest. Install batting between the attic s floor joists.

Joists are traditionally made from timber. You can use rigid foam panels or do as tom silva does with nearly all houses these days. 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.