How do you insulate a crawl space with a cinder block foundation?


What is the best practice to insulate a crawl space floor?

austin Fanning March 16, 2020Last updated: Sept. 10, 2020

Rear porch was was enclosed. Framed walls, insulated and drywalled

Crawl space has dirt floor, 3 cement block walls, open lattice wall to access crawl space, exposed floor joists 24'' o.c., height from ground to bottom of joists is 36"

Responses (4)

austin Fanning March 29, 2020, 6:26 p.m.

Hey Mike,

Plan for 4th wall( Lattice wall) was to cover interior with 1/2" P.T. plywood. The living area above crawl space would be heated with split unit or continuing existing hot water baseboard heat from adjacent room.

austin Fanning March 29, 2020, 6:27 p.m.

Also , project is located in 6b region, nort New Jersey

Mike Reynolds March 31, 2020, 12:19 p.m.

Hey Austin, so are you leaving the crawl space cold then? Correct me if I'm wrong but it sounds like
your plan then is to insulate between the joists for your upper floor (crawl space ceiling). If so, be sure to lay a poly membrane on the dirt to keep moisture in the ground. 

Are you by chance laying down any new flooring on it? Wondering if you had a plan for an air and vapor barrier between your conditioned space and unheated crawl space below. If you only had a subfloor then it would be easy to lay down a membrane first and put new flooring on top, that would be good for an air barrier, it would also keep the vapor barrier on the warm side.