Insulation For Between Floor Joists

When the basement or crawl space has vents installed insulating joist bays.

Insulation for between floor joists.

Encapsulating the floor system including duct work with thermo cloth and closed cell spray foam insulation creates a perfect wood framed floor system. 4b slab floors built directly on the ground. Either a rigid pir board from celotex can be cut to an exact fit and installed between the joists or a more flexible glass mineral wool gmw roll or slab from isover can be cut slightly oversize i e. Joist bays the open spaces between floor joists are prime hosts for insulation under specific circumstances.

We chose 2 in thick r 10 extruded polystyrene don t use expanded polystyrene which is a less effective air and moisture barrier. This is a floor where the timber floorboards are attached to floor joists and the insulation suspended on timber battens between the joists. The insulation should press right up against the floor between joists. I don t see addressed anywhere what to do when encounter these wires and pipes in the space we are trying to insulate.

We have an old house and want to insulate between the floor joists but there are wires and pipes running everywhere. 10mm wider then necessary to ensure a friction fit when installed between the joists. Gaps between the insulation and the floor can lead to inefficiency and heat loss. Do we cover them with the insulation insulate around them.

Fiberglass insulation batts or rolls are the most economical and easiest diy choice for insulating between the floor joist in a crawl space. I don t want to create more problems. 4d extend insulation into joist space to reduce air flows. 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.

Rigid foam is the best insulation for rim joists. You want it snug but not to. Also insulate 4a any portion of the floor in a room that is cantilevered beyond the exterior wall below. 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.

You can insulate second floor rim joists following the same steps shown here if you happen to tear out a ceiling during remodeling.