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Carpenter ants--how big a deal are they?


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Of course it depends... but, what is the likelihood of significant structural damage caused by ants?

I looked at a summer property for a buyer recently, to price repairs called out by the HI. There is a fair amount of frass in one area. Folks up here seem to call out the exterminator to kill the ants, then forget about it. Do you recommend destructive inspection if you see a large ant infestation?

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I once looked at a sunroom that had loose aluminum trim, the nails were all walking out. When I pulled the trim off, the double 2x10 header was fine over the door in the center but it was eaten almost completely away by the ends eight feet away on either side. Almost 20 feet of roof was precariously balanced on a 40" header in the center, and the ants were still active.

I think it's worth a look.

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If the main nest is in the house, it is a big deal. But often, the nest in the house is a satellite nest, with a few incubating eggs and some workers and food scroungers. They don't eat wood. They will hunt for soft, rotting wood or styrofoam in dark places to start new nests. If the house has a history of leaks, there's a better chance of a big nest, because a bit of rot will get them started.

I found a nest once inside a bundle of dry beveled cedar siding. It had been left laying in the dirt in an old barn. The two outer planks were usable and the rest were Swiss cheese.

A good pest control guy will search for the main nest, and it may be out in a rotten log or stump in the backyard.

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I always tell my clients that I cannot completely determine the amount of damage, if any, that the ants have caused. I will in severe cases recommend that a carpenter/contractor do a more intrusive investigation to determine the extent of the "activity". I once had a home with car decking flooring that had frass falling from the under-floor area and piled up on the crawl space floor, I didn't bother with a recommendation in that case. I simply told my clients that extensive and expensive repairs would be needed.

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I had a client a couple of years ago, detached garage, vinyl siding and finished interior. There was a double width overhead door installed. I found carpenter ant evidence at the framing at the overhead door. I have an attachment that goes with the NPMA 33 form if I find evidence of WDI, it warns of hidden damage and the need to remove obstructions (carpet, walls, etc.) to determine the extent of the damage.

After he moved in he opened up the wall above the overhead door and the header was little more than carpenter ants holding hands. They can be as bad as termites if left unchecked.

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The first evidence I saw in this crawl was a pile of frass under the front door. Then I noticed 3 or 4 strips of frass corresponding neatly with the floor joists. There was frass on the insulation batt when I pulled it aside. They appeared to be in the subfloor and were pushing frass out along the joists.

The flooring wasn't wet or rotten, but they probably started nesting under the rotten door sill and spread from there.

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There's something bad in there somewhere. There needs to be certain amount of opening things up just to treat effectively; I'd want to open it up and look when I was treating.

Carpenter ants, well entrenched in a house, can be surprisingly hard to get rid of.

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Of course it depends... but, what is the likelihood of significant structural damage caused by ants?

I looked at a summer property for a buyer recently, to price repairs called out by the HI. There is a fair amount of frass in one area. Folks up here seem to call out the exterminator to kill the ants, then forget about it. Do you recommend destructive inspection if you see a large ant infestation?

I think it depends on the ants. In the Willamette Valley, I find carpenter ant infestations on a weekly basis but rarely find any evidence of serious damage. On the Oregon coast, in contrast, I almost always find serious damage whenever I find the ants. It might have to do with the species. In the valley, we have Vicinus, Modoc, & Essigi. On the coast, the only one I find is Modoc and they're usually twice the size of the ones in the valley.

Has anyone else noticed variations in damage that correlate with location or species?

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Hi,

The frass that carpenter ants produce is very misleading. It actually takes them years to do damage equal to what a colony of termites can do in months; however, the piles of frass make it look like they've done substantial damage. Each of those tiny slivers of wood they discard doesn't look like it would take up much room; but when you put millions of those side-by-side the volume they take up is hundreds of times the size of the actual damage they do.

About a decade ago I got called by a friend to come look at his house. "Mike, I think I might have a carpenter ant infestation." I went over there and he pointed to the lower corner of an exterior basement door casing and told me to watch. Within moments a carpenter ant emerged and struck off across the lawn and another arrived and disappeared behind the trim. We watched for about ten minutes and counted hundreds coming and going.

His basement family room was lined with wood paneling applied on furring strip nailers over drywall. We started at the door and began removing the paneling. The gap behind the first sheet was packed with frass but when we cut a hole in the drywall to check the framing and sheathing it was fine. We started removing more sheets of paneling. I figured that we'd go until the shavings stopped and that would take us to the source of the shavings.

We went about 25 or 30 feet around that room before the shavings petered out below a south-facing window. As we progressed we kept finding ants as we'd pull the paneling off and by the time the frass had petered out it filled his large shop vac to the brim and we'd had to empty it - it almost filled a wheelbarrow.

I started tapping on the framing beneath the window and suddenly lots of soldiers appeared and assumed their aggressive stance. The wood sounded hollow. I hit the top of it with the blade of the wrecking bar and the top broke inward and all hell broke loose. The inside of that 2 by 4 was hollowed out and was packed with eggs. As soon as I broke that two-by open, ants swarmed all over the place. Some came after us and some were grabbing eggs and tried to move the cache. As I opened up the wall around that opening looking for more damage, he Worked frantically to gather them and those eggs up with his shop vac. so that they wouldn't be able to relocate the nursery. I removed the window and we stripped the drywall looking for more damage but there wasn't any.

That huge pile of frass was the result of them hollowing out a single horizontal two-by about five feet long. We removed it and nailed in a new one and restored the walls. Problem solved.

I would never have guessed that much frass could be created by so little damage.

ONE TEAM - ONE FIGHT!!!

Mike

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I can tell you from personal experience. They will take your house down.

My neighbor will concur. Fifteen years after he turned the key, he had to tear out and rebuild the south wall of his home.

I concur, had to tear a back room off our old house and completely rebuild due to carpenter ants. There were hundreds hiding in the walls.

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