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Hello..
Ive read some pest control companies are cancelling warranties for folks who have used spray foam insulation, or placed foam board on exterior basement walls because insects like to tunnel up in it. In your experience, is this a valid issue regarding foam, or is this misinformation designed to make foam insulation look bad?
Thanks
 

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A decade ago, I built a 48 by 48 foot barn. To reduce condensation, I used inch thick beadboard with a vapor barrier on both sides, in the roof, under the pole barn metal siding. At the peak, 35 feet in the air, mice are destroying it by digging between the vapor barrier.
 

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I've had insects tunnel into rigid foam board and white styrofoam board with that reflective mylar on one side. I even had mice nesting in the rigid foam board insulation I installed in my open crawl space ceiling.

I have not had a problem with insects getting into the spray foam that I used on part of the shed exterior. But spray foam that is exposed to the elements breaks down into sand like particles over time.
 

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Those big bumble bees that drill in wood will . they chew holes in my garage wood siding then in the foam sheets into the inside of the garage, and fly around till they get let out. Not that that answers your question.
 

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A decade ago, I built a 48 by 48 foot barn. To reduce condensation, I used inch thick beadboard with a vapor barrier on both sides, in the roof, under the pole barn metal siding. At the peak, 35 feet in the air, mice are destroying it by digging between the vapor barrier.
Time to use some mouse control. Poison or traps or what ever. Keep in mind they eat the wiring and plastic plumbing also.

To late now but vapor battier on both sides ? Have always understood its to used in one side only ?

As far as the OP. I have seen mice tunnel into it. Same as any other insulation. Just have to control them. Not familiar with insect issues.
 

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I think its location and luck of the draw.. I'm no expert, I'm just doing some research after reading about infestations in foam on green building advisor. For all I know it maybe rare, but examples of foam infestations keep popping up. You don't get any search results when you search "mineral wool ants termites" But many when you search "foam ants termites".

I joined the fb group "Pest Control Experts Worldwide" and was told..

Yes! Particularly with subterranean termites and carpenter/pine ants in my area! At least with the ants we see more of the foam pieces under said infested area!

We have had people use spray foam instead of having proofing works done for rats and mice and then complain that they are back and I just think well what do you expect.

We have treated foam-lined house boats sitting off shore a 1/4 mile for subterranean termites living in the foam board. It’s a nightmare to treat.
Also inspected a marina sitting on foam blocks off shore and termites were living in the foam block submerged in water. Crazy stuff and difficult to treat.
Foam insulation replaces the ground and becomes the ground for subterranean termites.

There's also many discussions regarding insects and foam on construction forums.
 

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The main issue is termites. They build mud tunnels up masonry or concrete to reach wood. These tunnels can extend ten to twenty feet. If it is behind foam, it is not visible. Most termite control companies rely on visual inspection to determine the presence of these tunnels to evaluate the efficacy of treatment programs. Makes perfect sense that they wouldn't honor warranties if changes were made that not only prevented them from being able to evaluate the presence of termites, but made an expensive structure possibly more attractive to termites. The seclusion of the foam wouldn't even necessarily force them to construct a mud tunnel. Regular barrier treatments would still work, but they are pricey.

Foam is only good for filling gaps and stopping air flow. It doesn't prevent anything from getting in. Insects can chew through it, and it's absolutely no deterrent to rodents. A trend that I see is people spray foaming attics. They spray the underside of the roof. The downside to this is, if you insulate the top of the ceiling the attic gets warm when the sun shines. This tends to dry things out. If you have a roof, even just installed, it leaks somewhere. It is the nature of screws and nails. Usually not enough to cause problems. But if you coat the bottom of the roof with a six inch layer of foam, every drop of water that ever backs under a shingle and leaks in a nail hole or comes in through a hail dent or a screw that backed out in a wind storm stays right there, on the wood. Have seen some deconstruction projects that point to the big layer of foam on the bottom of a roof being an incredibly bad idea.
 

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Hello..
Ive read some pest control companies are cancelling warranties for folks who have used spray foam insulation, or placed foam board on exterior basement walls because insects like to tunnel up in it. In your experience, is this a valid issue regarding foam, or is this misinformation designed to make foam insulation look bad?
Thanks
Never heard companies cancelling warranty due to foam insulation? Foam is a soft material, so of course insects or rodents could get through it if they want to.
Foam has to go on solid substrate and not bridge over a bunch of big gaps in a structure or unwanted critters could dig thru the foam and get in. You still need to have solid tight walls, foundations, etc.
 

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Supposedly rock wool insulation is insect resistant.

.
 

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Is thre any difference between pests tunneling into foam vs skooching between board and standard rolled bat insulation for protection?
My workshop is unheated/uninsulated below, with insulated living quarters above.
I had a vapor barrier of 2” spray foam between those ceiling joists (as in the floor upstairs has insulation beneath). Then stuffed batt into the joists to bring R value to code.
Rats got into the batt, but didn’t get into the spray foam. About to double up that spray foam….
 

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On another note, my cabin was initially not insulated. So many spiders it was nuts. No mice. I had it spray foamed. No spiders in 7-8 years it was money well spent.
I’d expect a sloppy job wouldn’t have had these results.
 

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On another note, my cabin was initially not insulated. So many spiders it was nuts. No mice. I had it spray foamed. No spiders in 7-8 years it was money well spent.
I’d expect a sloppy job wouldn’t have had these results.
The vapor barrier did more for the spiders than anything. Keep a structure dry and you keep a structure spider free. If you see spiders, your moisture control is not optimal for structural integrity, mold inhibition and good storage conditions.

On another note, I have seen fiberglass bat insulation in crawlspaces that was not properly hung and maintained sag and touch the floor and termites used it as a bridge to build mud tunnels to the floor beams.

Keep in mind, termites and carpenter ants eat wood, so foam is not going to be a problem. Sealing gaps during construction can prevent air flow. Rodents can detect the existence of cavities by air flow. Starting from scratch, having these gaps foamed is good. If their is an active rodent infestation, they will tunnel right through the foam that blocks their path, leaving a pile of foam confetti in their wake.

Rodents will nest in fiberglass bat insulation, if they have access to it. The fact that they have access to it is the main problem, as they shouldn't.
 

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From what Im reading, insects dont eat foam, but it reminds them of rotten wood so they nest there. But it sounds like most of the nests in foam are when the foam touch's the ground or foundation.
No, they don't eat it, they will take bites out of it and deposit them in a neat pile. The fact that they literally eat hardwood is to illustrate that foam offers no significant hurdle to them.

Nests aren't the issue. A termite colony can occupy a quarter acre. The issue, if your home is within the reach of the colony, is that it becomes a food source. If so it will be chemically marked and there will be constant efforts to make trade routes back to the capitol city. Foam makes that very easy for them and prevents you from seeing evidence until a good deal of damage is done. Keep in mind they can go all the way to the roof peak, tunneling through wood that tastes bad to find untreated wood, building mud tubes around obstacles, and hollowing out support members as they carry wood fiber back to the capitol city where the queen lives, possibly a hundred yards away. Sure, they could build the entirety of their colony in foam, even on a boat, but a more likely scenario is that they extend an arm of their road network into the piece of foam that is closest to the ground, in the most obscure location to access wood fiber in a structure.
 

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Carpenter ants tend to use a structure to build the entirety of their colony, they will use gaps, cracks, rotten wood and termite damage to their advantage, colony size is not as large but just as far reaching. They don't mind being exposed contrary to termites. They will set up shop in a structure and then send foragers from that structure, above ground, to bring food back. A barrier treatment with a microencapsulated toxicant will work well for them and any termite scouts that look for places to build a mud tunnel up an exterior concrete wall. To prevent termites from coming up inside of a dirt floor in a crawlspace, a soil barrier treatment is the industry standard.
 
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