Cut the foam into 8 ft long strips 1 8 in.
Best insulation for basement ceiling joists.
Moreover you can install it to insulate walls as well as crawl the spaces.
Blanket insulation may be made of fiberglass mineral wool other natural fibers or plastic fibers.
As you complete the installation there will be a reduction of noise within rooms and external areas.
Less than the height of the rim joist.
Then install rigid foam board insulation with all the seams taped like this illustration credit to building science.
Insulating the basement ceiling will keep most of the heat upstairs in the living space.
First you ll have to maneuver batts of insulation around the clutter of wires pipes and cross bracing in a typical basement ceiling.
To answer an implied question how would you get the floor warm if you insulated the basement ceiling.
Basement ceilings can easily be insulated with unfaced fiberglass batts or blankets installed between the floor joists and held in place with wire fishing line or spring metal supports called tiger claws.
It generally comes in rolls like fabric and is usually made in widths that match standard stud and joist spacing.
Rigid foam is the best insulation for rim joists.
Hold the batts in place by stapling their paper faced vapor retarders to the lower edges of the joists.
Install batt insulation in the joist bays with a 2 air gap.