Found out termites can chew through foam board insulation in 2 weeks

Read a study from Clemson University last week. They tested closed cell foam on a mud tube setup. Termites tunneled straight through a 4 inch panel in 14 days. I always thought closed cell was termite proof. Anyone else running foam board under slabs or should I just stick to treating the soil before every pour?

2 comments

2 Comments

wells.evan4d agoMost Upvoted

Whoa, hold on. I get why that study grabs your attention, but I'd take those lab results with a big grain of salt. They set up a perfect, no other food source scenario with a mud tube right against the foam. In the real world, termites are lazy and will take the easiest path, and if you've got proper gravel under the slab and a decent chemical barrier, they usually never even get near the foam. I've pulled up plenty of old foam board on jobs that was totally clean after 15 years. Your mileage may vary, sure, but I wouldn't ditch the foam based on one extreme test. Just make sure your soil treatment is solid and maybe use the borate-treated foam if you're really worried.

reese_lee4d ago

Wait, has anyone actually checked what the foam itself does to the vapor barrier underneath? Because if that foam traps moisture against the plastic, you could be trading termite worries for a mold issue on the slab, and that's a whole other can of worms. @wells.evan, your clean pulls are solid evidence, but I've seen chemical barriers fail after a few years when the soil shifts, and then the foam becomes the buffet nobody planned for.