Ants in your exterior foam?
user-901114
| Posted in General Questions on
Been working on a build over the past few years. It’s a cape style home in zone 6. I’ve insulated the floor of the top floor and walls below for now because I can’t afford to finish and heat the top floor. I have not heated the house yet. I’m seeing small winged ants crawling out of my north window in the top floor. The wall has exterior 2in foil faced tuff r polyiso taped with strapping and vinyl siding over it. I’ve recently sprayed the area with boric acid. Short of ripping the foam off the house, what else can I do?
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Replies
Stephen,
You might want to start by reading this GBA article: Coping With Termites and Carpenter Ants.
Stephen, If they are black, you have a colony of carpenter ants living in your foam. The winged ants indicate it is big enough that it wants to send out scouts to establish a satellite colony.
I had a similar problem. If you simply spray the workers you can get access to they will easily be replaced. You need to get every one of them - especially the queen. You can either hire an exterminator or use liquid bait like Ant-B-Gone that will be carried back to nest. Look around the perimeter of the foundation and see if you can find their foraging trail. They don't eat the foam, just remove it to enlarge their living area. They still need access to food and that is almost always by a trail onto the ground.
Once you get rid of them consider spraying the framing, exposed foam, foundation and surrounding grade with Bor-a-care. And consider doing this for periodically as routine part of the house maintenance.
Insect damage is the achilles heel of foam insulation which we often choose to ignore because we like it's other properties. Good luck!
Stephen,
Just curious, but have you checked to see if the foam in the affected area is damp?
Like Dr Joe's "perfect barn" an ant colony in your foam may be an indication of a moisture problem.
Lucas,
Much as I like Uncle Joe I found his description of the problems he found in his office when he renovated a bit dismissive. My observation of the many really extensive infestations of carpenter ants in foam is that moisture is only sometimes present. I have found them in bone dry sheets on the south side of attics. The foam mimics the decaying stumps they like to nest in, and in climates such as here in the PNW where there are lots of sources of water near the colony, they aren't as concerned with nesting in a damp place. I don't mean to imply that checking for a moisture problem isn't a good idea, but water isn't a pre-condition for an infestation.
Malcolm,
Thanks for your observations and I'm sure you have a point.
I just like to raise the possibility that there may be more going on than meets the eye.
If I were Stephen, I would probably "dig a little deeper" just to make sure there isn't a flashing error or some other issue lurking nearby.
Thanks for the advice all. I would be shocked if there were any moisture problems. It's the top and only window set high and under a 1 foot overhang. Digging into this will require ripping off the siding due to built in j channel. . My message to any diy green builders is to stay far away from foam. It's just not worth the risk and work required. Find another way..