Rigid Foam Under Rat Slab

3353 Views 6 Replies 3 Participants Last post by tomdor, Jan 3, 2013

tomdor

Discussion Starter · Dec 31, 2012

Okay, so I've searched the web and searched through this forum and can't find the answer to one question I have.

I will be pouring a rat slab into my crawl space to prevent the persistent buggers from tunneling under my footing. I also plan to make this a conditioned crawl.

Should I pour the rat slab over rigid foam? Would it make a difference? I'm in climate zone 4c (Seattle)?

Thanks!

Save

1 - 7 of 7 Posts

Windows on Wash

· #2 · Dec 31, 2012

Why kind of rigid foam?

I can't hurt.

Save

Gary in WA

· #3 · Jan 1, 2013

http://www.house-energy.com/Insulation/Slab-Insulation.htm

http://www.wrcc.dri.edu/cgi-bin/cliGCStH.pl?watac1

Gary
PS. install 6mill poly under the whole slab first...

Save

Reactions: 1

tomdor

Discussion Starter · #4 · Jan 1, 2013

Happy New Year and thanks for the great info in the links!

I was planning on using XPS but do you know if I can use R-Matte Plus ISO?

Thanks

Save

Windows on Wash

· #5 · Jan 2, 2013

Use XPS under the slabs.

ISOs are moisture sensitive.

Save

Reactions: 1

Gary in WA

· #6 · Jan 3, 2013

The foil-facing is good IF there is a space, but not with a slab over it.... Just don't puncture the foil with rocks or pea gravel (in the concrete mix), hmm.....; http://www.inspectapedia.com/Energy/Insulation_Polyisocyanurate_Slab.htm

Or it can/will absorb 7 times more water in the test as XPS; http://commercial.owenscorning.com/assets/0/144/172/174/e45fe07d-5cc9-4e4b-866a-5e35d75090ec.pdf

Gary

Save

tomdor

Discussion Starter · #7 · Jan 3, 2013

hmm yeah...my experience with the foil is that if often gets a small puncture if you look at it the wrong way.

Thanks for the add'l info

Save

1 - 7 of 7 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.

Top Contributors this Month