Morgan Martin’s dilemma is what to do about the crawl space beneath the house, identified in a recent energy audit as a source of air leaks and energy loss.
The joist bays above the crawl space have been insulated with fiberglass batts, but the subflooring has not been air-sealed. A local green building company recommends removing the batts and taping and caulking all the gaps in the floor (that is, the crawl space ceiling). Once that’s accomplished, the builder lists three options:
- Put the fiberglass batts back in place with no additional insulation;
- Apply rigid polystyrene insulation, then reinstall the fiberglass batts; or
- Forget the fiberglass and spray BASF Spraytite closed-cell foam on the underside of the floor sheathing.
There are two complications: “Please know before I go on that I have chemical sensitivity issues,” Morgan Martin writes in this Q&A post at GreenBuildingAdvisor , “so this is why this decision is such a big deal for me.”
There’s also a concern about rats. The crawl space had been infested with them, and while it’s since been cleaned and sealed, Morgan questions whether the polyethylene sheeting that covers the dirt floor will be enough to keep them out in the future, and that may affect whatever option he chooses.
But the main issue seems to be the potential health effects of polyurethane foam, discussed in a number of previous Q&A posts. “We have the option of doing a 2-in. layer of the foam and then putting the fiberglass back up over it or doing a 4.5-in. layer and not using the fiberglass at all,” Morgan says. “Even with all this reassurance it will be safe for me and my family, I have severe reservations about using the spray foam — even though the green builder…