Writing from the Pacific Northwest, Malcolm Taylor dives into a problem experienced by many homeowners and builders: a carpenter ant infestation in rigid foam insulation.
“I am involved with two projects right now that have carpenter ant infestations — and in both cases they are in the foam,” Taylor writes in this Q&A post at GreenBuildingAdvisor. “One is particularly difficult to fix as it is a flat roof with tar and gravel above and a wood tongue-and-groove ceiling, making it hard to get at the nests.”
For a season, the owners tried to deal with the problem themselves, but their efforts backfired. Instead of a single nest, there are now “multiple nests across the whole roof,” Taylor says. Exterminators brought in to find a solution say that it may take more than a year to get rid of the insects, and of course during that time the ants will continue to damage the building.
“When this topic comes up, typically the responses tend to fall into three categories,” Taylor says. “First, ‘don’t think about it — [foam] is used all the time so it must be all right’; second, ‘as long as the foam is dry they won’t move in’; and third, ‘treated foam is available.’ “
Taylor has found that carpenter ants will move into foam whether it’s damp or not. All they need is a source of moisture nearby. As to foam treated with an insecticide, he adds, no one seems to stock it.
“As foam is now increasingly being used as an integral part of many structures, and often in a load-bearing capacity, how wise is it to use a material that is so vulnerable to pest and insect damage?” he asks. That’s the topic for this…