Strange powdering of closed-cell foam at chimney
greenhouse437
| Posted in Green Products and Materials on
Three years ago we had closed-cell foam installed in our attic under the roof. All’s been going well, esp. energy savings and comfort. Last week my wife noticed powder from the insulation falling from the top of the chimney in one area. See photos.
While my first thought was ant infestation, second thought was that it’s the kind of powdering that could occur if someone trimmed the insulation with a blade–though we can’t figure out how that would have happened.
On outside photo, I do notice a bend in the copper flashing in the area corresponding to the powdering, but that may not be new.
Any ideas? Don’t think water leakage would do that.
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Replies
I would guess it is critters. You might have a water leak around the chimney.
Might be worth while to cut out a section of the foam (big hole saw works the best) where you see a lot of debris and check the roof deck. You can seal the hole back up with some canned foam.
@Akos, thanks. Just got off the phone with an extermination company and his first guess was flying squirrels--which was the last thing I would have thought. I think once he heard about 'spray foam' he lost interest since he would need that cleared away to do any treatment. We can't see how squirrels or any animal could get access to that cage on top of chimney. Anyway your hole saw idea is a good one, except that if it's bees I'd be concerned about drilling into the nest and facing an angry swarm.
I would be suspicious of carpenter ants. They love foam.
@Steve Knapp, yes, that would our least favorite discovery. With all that foam under the eaves, this would make a very difficult job for any exterminator. I have never seen any mention of this issue with spray foaming before. And of course if the ants reached that high level of the house one has to wonder where else in the house they've been established. So far no wood shavings.
Well, tree cover and carpenter ants seem to go together. (I noticed some limbs hanging over your roof in one picture.) The fact that carpenter ants are more active at night makes them harder to spot as well. FWIW. You often see scout ants out during the day. If you see one, try to follow it back to your home and see where it goes. Bait systems seem to work well with carpenter ants. Trimming back trees is also a good idea.
@Steve Knapp, thanks actually the photo is an illusion of closeness from a telephoto lens. We've made sure there are no tree branches over our roof. Always made sure of that. We're hoping we have driller bees instead. we've only occasionally noticed ants over the years, usually with the change of seasons and have not noticed that 'frass' anywhere. Still until we have an exterminator take a look--hopefully tomorrow--we're going to be a little anxious.
This looks suspiciously similar to a carpenter ant infestation that we had in some XPS foam that was used as spacers for lumber storage. The easiest way to find out would be to put some honeywater nearby and then follow them. Late in the evening is the best time for this. Satellite nests can be quite small and cutting into the foam may give you a false sense of security if you happen to cut in the wrong spot. In our case, a few hundred ants lived in a roughly 1.5 x 10 x 10 piece of foam.
@Juli Hmm, when you say put some honeywater nearby, not sure that would work here unless you mean on the foam itself near where it's falling from. So far no ants--or whatever they are-- as far as i know have broken through the foam into the attic, the trickle of the foam dust is all we see. I can't really get to the roof.
Had an exterminator out today. His gut said it wasn't ants but could be some critter. Said white powder could be the white caulking outside of roofing flashing. Said ants usually gravitate towards moisture, and would show some excreta or a few dead ants. Recommended I get a roofing co or chimney co to check flashing and inspect chimney top from outside. Has to be rotted wood or moisture for there to be ants. If it's ants, he can come by with a micro-injection guaranteed for 90 days.
After he left I re-inspected and finally found a scout ant coming from the area where chimney meets foam. So I have a roofing company coming to see what needs to be done. And we'll have a micro-injection in a few days. I would spray it myself in the meantime but perhaps wait for company to come to get them all in once place.
I can't figure out where moisture would be coming from except if flashing has a leak or if water is somehow pooling inside chimney.
With all due respect to exterminator guy, I've had a carpenter ant nest in completely dry foam - it's possible that ants prefer moist wood or moist foam, but they are absolutely capable of living in dry foam.
To get rid of ants if it is indeed ants, bait them with Bayer's Advance (protein based) bait and at the same time with Syngenta's Optigard (sweet) bait. Both available on Amazon for around $50 combined. The latter can just be spread on the roof around the foam and you can check a few hours later if you've caught some. If not, congratulations, you probably don't have ants!
Chimneys often leak a little, either through flashing joints or through the bricks absorbing water. I can almost guarantee you have some moisture around the chimney--enough to keep ants happy. And as mentioned, they love digging in foam, though foam companies will tout that their products "provide no food value." That's true, but it makes a nice nest. I would cut the foam away from the chimney (it shouldn't be installed tight to the brick anyway) and see what's really going on.
@Michael Maines I regret I hadn't posted photos of the chimney assembly itself, which point to the very things you mention. This 1924 construction apparently has improper flashing, coping that doesn't extend far enough outward to drip onto the singles instead of the chimney itself, and the bricks sorely need re-pointing. See photos.
Last year I had a liner put in for my new boiler; you would have thought that the chimney company would have said something about this problem waiting to happen so I could have taken care of it all at once. Note that the photos of the liner top are with the top capping temporarily removed for the liner installation.
@Jui_Fegi, yes, not sure why it wasn't apparent to exterminator it was ants. Those fine particles would seem typical of carpenter ants.