How To Insulate A Floor Over A Crawl Space. If you have a vented crawl space, we recommend batt insulation installed between the floor joists. If there is a history of flooding or water leakage in the crawlspace, provide proper drainage.
Fiberglass insulation batts or rolls are the most economical and easiest diy choice for insulating between the floor joist in a crawl space. Ventilated crawl spaces can make use of simple batt insulation installed between floor rafters. A better approach would be to cover the ground of the crawl space with plastic to reduce the moisture, and reduce the ventilation in your crawl space during the winter.