crawl space insulation

Asked by Neil Miller
Troy, MI

Spray on foam or solid styrofoam. low clearance crawlspace. Only 12 years old. Heard foam can allow wood to rot. Every contractor seems to have a different system or opinion. 19 X 25 foot crawl space.


Sean Lintow Sr

Answered by Sean Lintow Sr

Naperville, IL

SLS Construction & Building Solutions

March 4, 2014

Either method will work though sprayed on foam is generally easier to apply & get a better job. One big item is making sure the area is ventilated quite well while the work is going on & if utilizing spray foam, no one is home & the house is pressurized. Foam does not allow wood to rot, moisture does that so you need to make sure you have an adequate vapor barrier placed on the ground & that laps up the wall. Any other moisture sources need to be corrected, vents closed & sealed (leaking pipes, incorrect grade, etc...) and the wood / space is dried out. As for the foam - closed cell only so it doesn't hold any moisture. Along those lines make sure the rim joist areas are sprayed or filled in properly. Do not forget that per codes a supply line must be utilized. For more you may wish to read up on "sealed crawls" especially from Building Science .com

Tagged In: spray foam, green insulation

Do you have a question about greening your home? GreenHomeGuide invites you to Ask A Pro. Let our network of experienced green building professionals – architects, designers, contractors, electricians, energy experts, landscapers, tile & stone specialists, and more – help you find the right solution.