A while back I posted a question about a “rolled plastic-coated insulation” for can be used for a code-compliant exposed installation in crawl spaces that a builder friend mentioned to me. He couldn’t recall the name and so Iwas asking if anyone else knew of it.
A few people answered, asking me to let them know what I found out. Well, after searching the internet, asking a former Building Commissioner (and current Codes Expert) and having a supplier double-check my research, I have found that ONLY Dow’s “Thermax” (formerly produced by Celotex) has paper work for unprotected interior installation (i.e. no gyp board covering for fire protection required).
The details that I worked out with Stego Industries for moisture-proofing my crawl space are VERY promising: (1) Paint the inside of the perimeter conc block stemwall with “Stego Mastic” for a true moisture barrier (2) Use that clean, dry surface for adhering foil-faced rigid insulation (Thermax) (3) Cover the dirt floor with their 15 mil, fiber-reinforced Stego Wrap, sealing around interior spread footings with the Stego Mastic and taping all seams with Stego Tape (sim. to Air infiltration barrier tape) (4) Turn the Stego Wrap up 6″ over the foil-faced rigid and seal with Stego Tape. What makes Stego Wrap so special is that is made from only virgin plastic; the standard 6 mil poly is mostly from recycled plastics and is neither a vapor barrier nor very long-lived.
Andrew GIl
Architect/ Builder
Replies
This thread is a bit old so I would appreciate: 1) your renewed interest in this matter 2) updates on your installation (if completed) with respect to durability, ease of application etc.
THE PROBLEM I have a 140 year old home which is built on a rubble foundation. Approximately 1600 sq ft of "ventilated "crawl space. This has an non leveled, uneven dirt floor. The joists are sound without evidence of dry rot or other decay (the place has been standing for 140 years), the walls are rubble approximately 18 inches thick but have sufficient perforations to qualify the space as ventilated and permeable to insects, and other critters. The head room is variable from 30 inches to what appears to be a low end of 14 or so inches. I have read your posts, as well as the replies.
My thoughts are a) to close perforations from the outside (re point )the foundation walls as much possible b) place a rodent non permeable barrier on the inside SS galvanized screen hardware cloth c) apply a product something like the Stego Wrap or apply or alternative agent such as neutrocrete. The neutrocrete appears to have the advantage in ease of application (spray/trowel on) vs 14 wide rolls for stegowrap which would have to be adjusted around piers. How has your installation held up? Does anyone else have other ideas?
Thanks for your interest
bump
half of good living is staying out of bad situations
Thanks for the Bumped info. Additional info on Stego mastic needed. As you can imagine rubble walls are very rough and irregular so to avoid using tank car full loads of mastic is there something which can be rolled on (wide a long nap rollar) or brushed on with a mop like asphalt (I don't want to mess with hot stuff ), that would adhere and not flake or peel off later? What kind of prep is needed? I don't have much space to work with so power washing might not be the way to go. Finally after the "mastic" is on does the THermax need to adhere tightly to the walls/mastic combo?