I have 2LB foam on the exterior of my basement walls.  I want to know if stucco, cement parge or some other type of treatment would adhere to the foam.  I'm afraid it wont so I'm thinking of attaching wire mesh with tap cons thru the foam and into the block.  Any advice is appreciated.  thanks!

I've used fiber cement applied directly to roughened XPS foam without problems.

The surface of 2 lb foam can be sorta slick, so you might consider whether or not a little rasping might be wise.

Thank you both for the input. I have painted it for the time being to protect it from UV rays until I figure out the best way to go with it. So, the surface is definitely smooth now of course because of the paint. I guess I could rasp off all of the paint possibly. Ugh..

Jonr- When you say fiber cement are you talking about the board fastened to furring strips or an actual fiber cement product that gets troweled on?

Ideally what I want is a product that I can trowel on directly to the foam, is flexable enough not to crack and split down the road, and will be hard like cement to keep the critters from chewing through it, etc. I am going for a stone/bolder type of look to the basement walls when its all done. The problem I keep running into is that I cannot find anyone who has done this and knows it has withstood the test of time for awhile. I live in NW Pennsylvania so I have big sweeps in hot, cold, and humidity levels that would affect the product i put on.

Thanks again!!

I used a polymer-modified product called BTS Plus from STO over ICF above and slightly below ground level. I applied it last year in less than ideal conditions (temp below recommended) and have found it to stand up remarkably well. I needed to remove it in a few places and it was a bit of a trial. Check it out and see if it is what you are looking for.

When you say fiber cement are you talking about the board fastened to furring strips or an actual fiber cement product that gets troweled on?

I troweled it on, although a mortar sprayer (www.mortarsprayer.com) would have helped.

Well I did a little research and then called a distributor of the "BTS Plus" located in Cleveland. They actually don't sell that now but do sell an improved version. However, the rep I talked with did not recommend it. He said even though you may get it to adhere in the beginning, after a few freezing and thawing periods there is a real good chance that it would start to come off. He said it won't adhere properly to the foam. I suppose if the foam was rasped enough to make the surface rough and porous then certain products might actually bond with it but again after some seasons pass it might start to pull away.

after a few freezing and thawing periods there is a real good chance that it would start to come off.

Mine has survived at least 30, likely more.

He said it won't adhere properly to the foam.

That's odd, because it is made as a foam adhesive for exterior systems. Was there something else he was selling instead?

Maybe he didn't really know anything about the BTS Plus. When I asked for that specifically he just said they sell the improved version. So who knows I guess. I think I will try a few other places and find out if someone carries the actual BTS Plus........

I'm all for an improved version, but I dropped by my source today and he couldn't come up with anything that might fit that description.

My coating is an 1/8" thick with nothing over it. All it does is hide the small amount of ICF foam surface down by the ground. Is this going to be the final covering for exposed basement walls or are you ultimately going to do stucco over?

I think mine was


QUIKRETE® One Coat Fiberglass Reinforced Stucco (No. 1200)

My basement is into the side of a hill so half of it is totally exposed above grade and the other half has about 4 feet sticking out of the ground. I contacted a spray foam company. He recommended digging out spots of insulation, tapcon a normal metal fastner strap for masonry walls direclty to the exposed block and then can spray foam the portion of insulation I dug out so only the end of the strap is exposed. Then I can mount mesh to the straps and apply either a fibrous parge or stucco. I'm trying to get the basement to look like an exposed bolder or solid rock when its done. It fits the overall contemporary design of the home.

Jonr- I'm afraid that any stucco or parge will not adhere to my painted 2lb spray foam alone without having clips and mesh added to it. Especially after a bunch of freeze and thaw cycles. I also think to get it to look like a solid rock wall i will need to trowel on the product. I will definitely check into the Quikrete No.1200.

Thanks......

> I'm afraid that any stucco or parge will not adhere to my painted 2lb spray foam

Agreed, paint might change things and require mesh. Maybe self adhesive fiberglass mesh would be enough.

Mine (roughened but no paint, no mesh) has survived several winters with lots of freeze/thaw cycles with no signs of problems.

Hmmm. Interesting. That sure would save me a ton of work. I may try a section of it and see how it goes. Thanks again all...