Affixing Insulaton Sheeting In Crawl Space – Need Help
Rock1985
| Posted in Energy, Heating & Insulation on
I am feeling very stupid and desperately seeking help. I am trying to affix 2 inch thick sheets of foil faced Thermax insulation sheeting to the walls of my crawl space without using mechanical fasteners drilled into the concrete cinder blocks. I have tried using two types of construction adhesives (Liquid Nails Heavy Duty and Locktite PowerGrab Foam Board Adhesive) with no luck. Can someone give me any suggestions that will help. Thanks.
Replies
Foamboard
I have used PL300 successfully to attach foamboard to concrete walls. Others have used minimally expanding foam to do the same, but I have no experience with it.
With PL300 I place large dollops of it on the back of the board at roughly 16" centers both ways and press the board to the wall. Then pull it off to see that each spot has made good contact. After resetting a few boards I place a 2x4 accross them and use kickers to hold it up and keep slight pressure on the board for several hours while the adhesive sets.
The walls must be dry and free of dirt and dust for the PL300 to grab hold. In cool conditions, such as a crawl space the adhesive may take up to 24 hours to set.
Though you don't want to use fasteners, a few judiciously placed Tappcons with fender washers can help a lot, and they are easy to use in block walls. Just don't over tighten them and strip them out.
Is the adhesive not sticking to the concrete or the foam?
RE: Is the adhesive not sticking
I appears as though the adhesive is not curing after a 24 hour period. When the boards came off, the adhesive was sticking to both the board and the concrete block wall. Any suggestions?
Since it's aluminum faced, you can use a regular glue like PL Premium for instance - it uses moisture to help cure. Gun foam glue will do the same.
A solvent based adhesive like Liquid Nails will set very slowly between foam (especially foil faced) and concrete, since the solvent can't evaporate. Don't know what the other stuff is like.
A moisture-setting product (some of the PL line, eg) will do a little better, especially if you can wet down the concrete first.
Solvent based.
Adhesives like Liquid Nails and other construction adhesives that are solvent based will disolve the foam. Intiallly they seem to adhere but since they are dissolving the foam board as they set up the only real adhesion is from the intial tackyness of the adhesive. After it has set it is only suck to the non foam surface, while the foam has a void eaten into the back side of it.
Most foam adhesives are either water based or made with solvents that do not attack the foam and dissolve it.
Don't ask me how I know this :)
Dave, it's foil-faced insulation.
Giveup on glue.
This is what I did. I made a bunch of "L" brackets and attached them to the floor joists tight against the foam. With 2" foam you only need 3 for each 8' section of board. Fit your foam as tightly as possible and tape the joints. After 2 years I returned to find all the foam in place and tight to the concrete. Another way is if your foam fits from the joists to the footing, a 1X2 nailing strip at the top and one Hiltyed to the footing works not bad.
Thanks For The Suggestions
Thanks for all your suggestions. I purchased insulation hangers (stick clips) from a local building supply company. Stick clips consists of a nail attached to a flat metal plate. I affixed the hangers to the concrete block wall with Locktite PL Advanced construction adhesive. Once the adhesive cured (usually with 24 hours), I impaled the foam insulation into the clips. The clips are capped with "washers." So far the insulation has not fallen down and I do not expect it to. Again thanks for all your suggestions.