About 4 years ago I put 3/4 inch thick foam insulation board on the roof beams of my garage attic. This is the type that has foil on either side of the foam. All seams were taped and the job went well. Immediately I felt a difference in peak temperatures during that summer. All seemed well. About 2 years ago, I noticed that the old Camaro was getting a deposit dropped upon it's rear spoiler. It was a very, very fine dust the color of sawdust. I felt it was a carpenter bee at first, though I could never see one milling about, nor could I find a hole above the car. This year as it continued to occur on a consistent basis, I decided to inspect the attic and see if maybe a mouse house was under construction. I found a bunch more of this fine dust. No tracks in it and no evidence of a hut. Well I had had enough of this dust piling up on the car, so I took a caulk gun and sealed off the seams in the flooring just above the car. Problem solved? Nope. Now the dust was in a line moving up the rear fender and onto the convertible top. That was too much for me. I went again into the attic, this time with a flashlight. I determined that the dust was coming from in between the sheets of insulation. A couple of smacks against that spot and I could hear some stuff rolling down the topside of the board, and maybe some other residual noise. Thinking again there is a mouse hut up there, but it doesn't make sense due to the heat that must occur in that cavity. As I pondered the scenario, I noticed the area around the seam that I just slapped was starting to crawl. Ants, and a hole hell of a lot of them. These things had been bringing mouthfuls of the foam down to the flooring level and were dropping it through the seam. I tore away some of the foil and saw just how bad it was. Tunnels and hollows up and down both boards. No wood damage thankfully, but this foam board is like an ant farm. I ripped a bunch of it away and used the wet vac to suck up all I could, spraying ant poison on the area afterwards. Ugh. I hope I don't have more of this going on.
Strange, I never heard of ants liking foam. I am wondering if the foam you used has a soy addictive to it. I just can't visualize that the pure petroleum based foams would have that happen.
myway, keep us informed on outcome, I have used some of that and now I will go check.. and you mentioned old camaro, convertible.. u mm year model info got a restoration 67 rs, convertible in garage...
Hmm, I was thinking of doing something similar, now I need to rethink. Is that "blueboard" or white styrofoam? It looks blueish in the photo, but I generally see the foil on the white stuff. It would be nice to know if it makes any difference as far as the ants are concerned. Greg
Myway, Do you remember the brand name of the product you put in. I called my foam guru and he said if you have the brand he might be able to help.
Schlot, If there is foil on both sides then there probably is condensation on the warm side due to a double vapor barrier affect. With two impermeable surfaces on a wall the warm side of the second will get damp. Your shingle question is spot on.
Found another spot they are working on too. Shingles are fine and the trim is all vinyl and aluminum. Not sure what makes that so attractive. The roof must bake the tar out of them during the day? Nothing between the back of the foil and the shingle except the plywood roof base.
