Demoing Spray Foam
The trick to tearing out this insulation without damaging pipes and wires.
I’m about to start remodeling a project whose walls are insulated with spray foam. I’ve found the stuff is surprisingly hard to tear out. Any tips?
—Howard via email
Andy Engel replies: Demoing spray foam has challenges. You can’t just pull it out like batt insulation, and it’s hard to determine what else is buried in the foam. Wires? Pipes? Jimmy Hoffa? Maybe, but where? A digital wall scanner is a great tool for locating these things. If you don’t have one, you can look for clues such as outlets and switches. Get down in the basement or crawlspace and up in the attic and see if you can figure out the paths the mechanicals take.
Even when you’ve found the origins of mechanicals, you can’t be sure what turns they take behind the foam. In the past, I’ve carefully probed the foam with an insulation knife to find pipes and wires, but I recently found a much faster method. I simply run a reciprocating saw through the foam, cutting with the non-toothed side of the blade. This goes through foam like a hot, noisy knife through butter, with little chance of damaging wires or pipes.
To actually demo the structure, the easiest thing is to cut the whole assembly into manageable chunks and haul them off to the dumpster. As much fun as wholesale destruction is, a lot of projects involve just a couple of stud bays in order to add a window or a door. In that case, I excavate the spray foam piecemeal.
Open-cell foam is relatively easy—you can literally thrust your fingers into the stuff and claw out handfuls. It’s easier, though, to separate the foam from the framing members using the reciprocating-saw trick above, then pry out big chunks with a flat bar. Closed-cell foam is far more difficult, but the technique is the same.
Whether open-cell or closed-cell, I don’t just empty trash cans of foam debris into the dumpster. I bag it up first to keep the wind from distributing it throughout the neighborhood. Also, it’s a good idea to wear a dust mask when tearing out foam, particularly the lighter open-cell variety. Trust me when I tell you that sucking a flake of foam into your lungs won’t be the best part of your day.
From Fine Homebuilding #300