This method can be hundreds of dollar less than the cost of using the commercially applied spray foam.
Rigid insulation between floor joists.
Joist bays the open spaces between floor joists are prime hosts for insulation under specific circumstances.
When the basement or crawl space has vents installed insulating joist bays.
Cut rigid foam insulation into strips with a table saw or a circular saw.
A do it yourself friendly method for sealing and insulating the rim joist or band joist area is to use rigid foam up against the rim joist.
Run a bead of acrylic caulk around each section of foam to form an airtight barrier.
How to finish a basement.
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.
The insulation should press right up against the floor between joists.
Seal and insulate using rigid foam board insulation.
Fill gaps larger than 1 4 in.
Gaps between the insulation and the floor can lead to inefficiency and heat loss.