# Mineral wool preferable to EPS for below-grade use?



## iLikeDirt (Apr 27, 2014)

My house's structure is made of wood and there are subterranean termites (non-formosan) in my yard and area. I am planning to excavate and insulate the slab perimeter in the interests of saving on heating, but am worried about creating a termite highway.
I figure XPS is right out, and I'm not sure about termite-treated EPS either. The availability, price per R, and ease of installation are attractive, but since the advertised termite resistance just comes from a chemical treatment, I worry that it will fade or leach out over time.

I've considered foamglas, which would be ideal due to its many desirable qualities, but it's ridiculously expensive compared to the alternatives.
What about rigid mineral wool boards? I see people online claiming it's resistant to termites, but I've been unable to locate any real confirmation or denial of this. My sense is that the mineral wool industry would be advertising this if it were true (as the foamglas industry does). So what's the skinny?


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## Windows on Wash (Aug 30, 2011)

The rigid mineral wool stuff is very cool stuff. Don't see why it wouldn't work. 

The regular stuff is great and seems to be very stable and insect resistant.


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## iLikeDirt (Apr 27, 2014)

Thanks WoW. Do you happen to know what makes the rigid boards insect-resistant? Is it just the physical character of the fibers? Or a residual chemical from the production process? Or both?


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## Windows on Wash (Aug 30, 2011)

The substrate itself.

Its basically rock...they don't care for it and can't seem to process it if memory serves me correctly.


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## joecaption (Nov 30, 2011)

Get a real chemical treatment not some silly bait stations and there would be no termites.
No form of insulation is going to stop termites!
The chemicals there using now should last at least 10 years.
There's always going to be termites out in the yard and will have no effect on your house.
Trying to insulate the outside of a slab will have 0 effect on heating or cooling lost.
Should have been done under the slab.


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## joecaption (Nov 30, 2011)

Get a real chemical treatment not some silly bait stations and there would be no termites.
No form of insulation is going to stop termites!
The chemicals there using now should last at least 10 years.
There's always going to be termites out in the yard and will have no effect on your house.
Trying to insulate the outside of a slab will have 0 effect on heating or cooling lost.
Should have been done under the slab.
Way more cost effective to check for air leaks, up dating windows, air sealing the attic and, adding insulation in the attic.


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## iLikeDirt (Apr 27, 2014)

joecaption said:


> Trying to insulate the outside of a slab will have 0 effect on heating or cooling lost.


Can you cite anything to back this up? This assertion appears to be contrary to the laws of thermodynamics, not to mention my own observations of snow melt patterns.

The point is not to stop the termites. It's to choose a form of insulation that's least attractive/habitable/sheltering to them so as to reap the benefits of slab edge insulation while not _increasing_ the risk of termite attack.

And who said anything about bait stations?


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## Nailbags (Feb 1, 2012)

you can lose up to 80% of your heat from the sides of the slab. Use ridged foam board. do a good treatment for termites and you should be good to go.


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