Insect issues with Spray Insulation?
I have an owner that was going to include open cell spray foam in the 2×6 exterior walls of his addition until someone mentioned to him that “insects like to burrow and inhabit spray foam”. I know that is an all-encompassing statement versus the types and formulations of spray foams available, but I wanted to reach out to anybody with experience with this. As the designer I have no skin in the game whichever way the owner goes, but I had not heard of the issue being more than a one-off problem from time to time. The project is on the edge of a pond in Massachusetts. Any suggestions for the owner?
Replies
He is right.
I have had exactly this problem. I have a raised home in New Orleans and insulated under one room with Handyfoam about 15 years ago. About 6 years ago that floor became infested with termites and the infestation was hidden by the foam for a long time until it became a major infestation. The entire floor had to be torn out as well as the walls and ceiling of that room and the room above it. What I later learned is that it is possible to get treated foam that will inhibit insect infestation. One method is with Borates but this paper www.croplifefoundation.org/upload/su%202003%20termites.pdf says that Borates are marginal and the pemetherins are better. I want to foam the entire underside of my house but will not until local installers start to put chemicals in the foam that will give me some piece of mind.
Note that termites are a different problem from bugs in general. Termites need to "communicate" with the soil, and build "tunnels" between the infested wood and the ground to accomplish this. Where foam is installed without an appropriate termite shield the foam serves as the "tunnel", and also allows the bugs to bore all the way to the surface of the wood (they normally remain about 1/16" beneath the wood surface).
Other bugs aren't particularly fond of foam, though rodents and the occasional bird will happily use it as a nesting area.
insect resistance of insulation
Performguard is an EPS product which includes borate. It is available in various configurations but not in a spray foam. The Oak Ridge National Laboratory in a paper discussing insect issues in insulation states that the borate treated EPS product appears to perform adequately. As far as I know, there is no spray foam product currently on the market that includes chemicals to deter termites or carpenter ants.
The paper from ORNL is at:
https://docs.google.com/viewer?url=http://www.ornl.gov/sci/buildings/2010/Session%2520PDFs/153_New.pdf&embedded=true
My area is a major gathering area for carpenter ants and I was surprised to find that they have no problems burrowing in fiberglass bats - I left a piece of the pink stuff on the ground for a couple of weeks and when I picked it up it was completely filled with a nest of carpenter ants complete with a large quantity of eggs.
One insulation that is reportedly resistant to both termites and carpenter ants is mineral wool insulation board. I plan on using this type of insulation the next time I have occasion to insulate. It is more expensive than fiberglass but less than foam. The mineral wool products that I have seen have been given an rating of R 4.0 to R4.1. Mineral wool is commonly used in curtain walls in high rise buildings because of its superior fire resistance over most other types of insulation.