Insulation Thickness Between Floor Joists

Best for unfinished walls floors and ceilings.

Insulation thickness between floor joists.

Joist bays the open spaces between floor joists are prime hosts for insulation under specific circumstances. The inside of the rim joist is sprayed from the sub floor to the bottom of the rim joist to drop the building envelope to the bottom of the joists. This is to prevent the joist. In this blog post we aim to provide a simple practical guide to the best practice methods for fitting insulation boards such as kingspan kooltherm k103 floorboard into a suspended timber floor.

The fiberglass will also need to be secured in place using wire mesh twine wood laths or other securing methods which can be an intensive project that adds to the overall cost. If the ground floor in question is of a suspended timber construction and whether this is a renovation or new build project then the insulation would normally be installed in the joist zone that is installed between the joists. At least 25mm of the joist must be left exposed to ensure air circulation. As for insulating below the joists an insulating laminate insulation bonded to plasterboard such as celotex pl4000 or a separate rigid pir insulation board finished with a separate sheet of plasterboard can be securely fixed to the joists to provide an internal finish to the roof.

These are pre cut sections of insulation that are usually fiberglass although cellulose mineral wool natural fibers and plastic versions are also available. Gaps between the insulation and the floor can lead to inefficiency and heat loss. This is a floor where the timber floorboards are attached to floor joists and the insulation suspended on timber battens between the joists. This perimeter insulation can be supported by blocks nailed to the underside of the joists.

Pack precision cut perimeter insulation boards around the room between the joists and the walls to prevent heat loss through thermal bridging. The insulation should press right up against the floor between joists. When the basement or crawl space has vents installed insulating joist bays. Encapsulating the floor system including duct work with thermo cloth and closed cell spray foam insulation creates a perfect wood framed floor system.

Wall insulation must extend 150mm below the upper edge of floor insulation to further reduce thermal. The insulation should be pushed tight to the underside of the floorboards.