Using Styrofoam Insulation Between Studs

Using styrofoam insulation for soundproofing.

Using styrofoam insulation between studs.

A typical question might go like this. There are two main ways of reducing thermal bridging through studs. Using the insulation within your wall cavity and other updated construction industry standards will allow you to use most any exterior finishing products fiber cement siding. Plywood has an r value of 1 25 and fiberglass batts have an r value of 3 14.

More effective insulation with r values ranging from 3 6 to 8 0 rigid foam sheathing has much better insulation per inch than other materials i e. Styrofoam is a brand name for a polystyrene foam board. There is nothing wrong with the addition of foamboard between the studs in that it is better than nothing. The question of validity arises with the excessive amount of labor involved producing a tight shell by this method.

The studs conduct more heat than the insulation between them. I d like to insulate between my studs with strips of 2 inch thick polyiso. I plan to cut the rigid foam pieces a little bit loose and seal the edges of the polyiso with canned spray foam. Here at gba readers regularly ask about the best way to install rigid foam insulation between studs or rafters.

After that thin furring strips are installed on top of the foam to provide a firm base for the drywall screws and drywall but can you run rigid foam between the studs just as you would do with fiberglass rolls or spray foam. Insulating boards are just one of the many types of foam insulation. Consider using spray foam insulation as well to seal smaller cracks and gaps. Acoustically it can reduce and muffle or help block noise from entering or leaving a room.

The panels provide a continuous energy efficient surface. 3 benefits of rigid foam sheathing. This eliminates thermal bridging which is the energy lost through wall studs. My question really is about the wisdom of using rigid foam board between studs.

Most builders who install a continuous layer of rigid insulation use rigid foam polyisocyanurate expanded polystyrene or extruded polystyrene. Rather than using long drywall screws i ripped down 3 4 plywood into furring strips and screwed them through the foam board into the studs with 3 screws make sure you mark your stud locations and an impact drill is your friend here. This makes it much easier to mount your sheetrock. The correct method of using rigid foam is to run continuous 4 foot by 8 foot sheets of the foam across the concrete basement wall making the rigid foam the de facto wall.

It s nothing more than framing with 2x6s or deeper studs and using any option of insulation product i e.