Cantilever Floor Insulation Detail

Cellulose cantilevered floor insulation.

Cantilever floor insulation detail.

Measure the size of the opening between the floor joists underneath the cantilevered overhang. I am working on a project where the main floor is cantilevered over the concrete foundation wall. Install insulation without misalignments compressions gaps or voids to fill the cantilever floor cavity making full contact with the top bottom and sides of a cantilevered floor cavity cover the bottom of the insulated cantilever floor cavities with a rigid weather resistant solid blocking material such as plywood or house siding. 2 cut pieces of 1 inch nonstructural sheathing board or 1 inch rigid foam sheathing to fit inside the.

The details i do have show a cantilever over a wood frame wall not a concrete foundation wall. When it comes to floor assemblies the stack effect works in your favor lowering rather than increasing the risk of moisture accumulation. If the floor is over a garage and has not already been insulated however it is recommended that each joist bay be filled with insulation. Fiberglass must be cut precisely to fill in the batts in the floor joists.

Cellulose insulation can be installed in the cantilever floor joists two ways through access from the crawl space or by drilling holes through the bottom of the overhang. Of course you need to protect the rigid foam from abuse with a layer of plywood osb or soffit material. Any suggestions would be greatly appreciated. This material has a few drawbacks as it still allows some airflow through the floor and is known to trap allergens and moisture which can leave.

You should only put in fiberglass insulation if you can access the cantilevered floor joist from a basement or crawl space. In addition to floors other cantilevered architectural features may require insulation. Usually only the cantilevered portion of the floor needs to be insulated.