I made a bit of a rookie error by using expired silicone caulk as a temporary adhesive for sticking rigid foam board to my rim joist. It's holding everything in place, but I'm concerned about whether this un-drying caulk will end up damaging the wood over time. Has anyone experienced this or have any insights?
3 Answers
It's interesting you mention it might not dry. Usually, silicone caulk hardens inside the tube if it’s not used up, so it’s surprising yours is still wet. Make sure you’re clear on what type you're using. If it stays as is, most likeliness isn’t going to hurt the wood but just keep it in check.
The drying of caulk depends on its specific formulation and how long it stays in place. Silicone caulks can create difficulties if you're planning on applying a clear finish later on, especially if you haven't painted over the wood. If it’s meant for lightweight sticking, just keep an eye on it, but generally, avoid using silicone if that’s your long-term plan.
Generally, caulk isn't really meant to be an adhesive, so it shouldn't cause any damage to the wood. Just keep in mind that you used the wrong product for this situation. It’s great that it’s keeping your foam board in place for now, but you might want to find a proper adhesive for a more permanent solution in the future.

I totally get that. I just needed something quick to hold the foam while I worked on getting full insulation. I'm not worried about finish carpentry right now!