Is it possible to use foam board up to a r-24 and place drywall directly over it? I'm doing my basement.?

Question

I'm asking because I need at least r-24 and if I don't have to frame and use bag insulation, I'd prefer not to. :)

Answer 1

What's going to hold your drywall. You need a frame of some sort the anchor your wall board. Build your frame 1/2 inch away from the wall so you can get a true plumb wall, don't worry you will not loose much space, use 1/2 think foam behind the frame studs and however thick you want in between, cover with heavy plastic and seal it to the studs, top frame and the floor, It looks like black silicone caulk. You can use heavy foam board on the floor and put 3/4 inch floor board down on top of that. It will be warm down there with out a heater as long as you seal it up good,

Answer 2

u can do it but u have to use t-bars to hold on foam board at 2 foot centres. the t-bar can be drill and fastened to concrete or block walls and then s***w drywall to t-bar which is steel ,should be available at drywall supply company. u can also use z-bar which is also a steel product. there is down side as to electrical,cable and phone has to have wire cases melted into it.plumbing is another consideration .one last note when u use foam board they are the vapour barrier so tape joints with tuck tape and do not use poly over foam board as this is a double vapour barrier and will cause problems down the road FYI when drywalling in basement keep it way from concrete or  block as it will wick moisture and be a mold problem

Answer 3

No offense to you or any others who answer, but in reading their answers their confusion my rest in some lack of details.

   In any case to attain an R-24 PERHAPS,,,

"Even though many foam insulation products are more expensive than other types of insulating materials, such as fiberglass, cellulose, etc., they are commonly used in buildings where there are space limitations or where very high R-values are desirable. Foam insulation R-values range from R-4 to R-8 per inch of thickness (2.54 cm), which is 2 to 3 times greater than most other insulating materials of the same thickness. Also, if the installation is carefully installed, foam insulation may control air infiltration more effectively than other types of insulation."

   You need no less than 3 inches of Construction grade foam sheet to insulate. That equates to 2 x 4 studs, and sheets cut to place between studs at a standard of 16 inches on center.

Just my two "sense"