Insulation, Radiant and Vapor Barriers - Attaching polystyrene

How do you attach the polystyrene panels to the walls in the crawlspace???

Thanx,
Cats

You mean EPS foam, right?

What sort of walls? I assume they aren't wood, so nails are out.

Perhaps clean concrete block or concrete. If so, then an adhesive is possible, you just need an adhesive that won't attack the EPS foam and will tolerate the moisture level of the crawlspace.

If the walls have soot or dirt on them, then you either clean the walls to prep for adhesive, or resort to fasteners.

I won't suggest masonry nails, I consider them an unreliable joke. Whatever you decide on, it most likely will require a 1/4 inch hole drilled with a masonry bit. Those plastic inserts used for sheetrock/concrete/block would do well. Use washers on the screws. A regular drill could work, a hammer drill is better, and a rotary hammer (though heavy) would make short work of drilling the series of holes.

You might consider an adhesive you could 'scrub' onto the walls, blending the dirt into the adhesive itself. Might work, might not work.


You might consider burying the bottom of the foam at the base of the wall, and holding the top in place with furring strips nailed to the joists. The more I think about it, the more I like this option.

The 'trench' digging shouldn't take anything more than gardener's tools.

FWIW, Owens Corning recommends furring strips to mount rigid foam insulation in a crawlspace.

Owens Corning sometimes says stupid stuff.

I emailed the Vytek division of Owens Corning, asking about application of Vytek vinyl siding over foil-faced polyiso insulation, and their response was they couldn't comment because they don't make foil-faced polyiso.

Doh.

Look around on a construction site, chances are you will see Styrofoam board placed in the trench prior to the concrete pour.

I didn't see any furring strips. The trench holds it in place.

You are right about placing the foam against the outside of the walls prior to filling. I understood the question to be about installling the foam board on the interior of the crawlspace. My mistake.

Well, you have caught me on the detail of inside/outside. I thought I saw it on both sides, perhaps I didn't.

Just seems to me that the goal is to hold the board next to the concrete. Furring strips are always a nusiance to install since the wood isn't the best and may split. I just thought that if it's possible to hold the insulation board in place without resorting to lots of fasteners and lots of furring strip, so much the better.

Sorry everyone, I should have made myself more clear.

I need to put the panels on the inside walls of my crawl space which are cement block. I already have the plastic on the dirt floor but have learned you should also put the panels on the walls. I was trying to find the best way to attach the panels to the walls.

If I were to use anchors, wouldn't that reduce the R-value of the panels???

I thought the plastic on the ground was supposed to also go up the walls a few inches. I did mine that way so that would interfere with the trench suggestion.

I like the idea of attaching the panels with adhesive. Is there one out there that won't "eat" the panels???

Sorry about not being clearer about what I am looking for.

Thanx again,
Cats

According to DAP's website, DAP panel and foam adhesive will adhere foam panels non-destructively.

Hope this helps.

Make sure the foam is tight up to the joist line and you put a R- 19 block of insulation up in the joist space there on the sill plate all around the home. DAP has some good stuff to use on the foam.;) ED

Just wanted to say thanx for all the responses & advice. This is why I love this site.

Cats

two things about foam...ants love to make their home in foam (saw it last week), not sure how the termites feel about the stuff. Phenolic foam was having a problem with eating metal when moisture was present although it has the best R value of about 8.3/inch. For detailing the installation see The Visual handbook by Charles Wing, an excellent reference many builders use.
It may be available in the public library.