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What can I cover my exterior foundation insulation with?

EHt2PWoEKw | Posted in General Questions on

I have 2 layers of 1.5″ XPS with staggered seams glued to a damp-proof block wall. The exposed wall ranges from 6″ to 2′ above grade. I saw the article with some suggestions for protection like SBC and protecto wrap, but wondered if I could use vertical vinyl siding. I will use a termite shield and drip edge over the foundation covering, and I have the foam covered with roll roofing down to the footer (30″ below grade). I was also considering stone veneer but was worried about how to attach it.

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  1. GBA Editor
  2. dickrussell | | #2

    On my own house I followed Riversong's suggestion and used SBC with SilPro C-21 modifier, applied over self-stick fiberglass mesh (see his last post in the thread Martin posted here). Yeah, it's a lot of work, but it's straightforward and gives a durable and nice-looking result. One reason I used it was because I had a number of areas where fastening a sheet material would have been awkward.

    If you use SBC, did you plan on removing the roll roofing (30# asphalt felt?) before applying the SBC? If the "roll roofing" is just 3' wide mineral-surfaced roofing, why isn't that enough (other than mediocre looks)?

    One thing that strikes me about your suggestion to use vertical vinyl siding is that you'd create hidden cavities up against the foam and open below grade. I don't know if that would be an invitation to bugs or not. Where are you located?

  3. EHt2PWoEKw | | #3

    I'm in southeast Virginia and I only put the roll roofing on to protect the foam where it won't be seen. It is not as easy on the eyes as other options. The hidden cavities that the vinyl siding create are my biggest concern with that option, but the siding would go over the roll roofing and the foam would still be somewhat protected. How did the self stick fiberglass mesh bond to XPS? What kind did you use?

  4. EHt2PWoEKw | | #4

    This is what she looks like now.

  5. EHt2PWoEKw | | #5

    Maybe this one will work...

  6. EHt2PWoEKw | | #6

    Guess I'm not allowed to post pics.

  7. user-723121 | | #7

    I use prefinished coil stock to cover exposed foundation insulation, comes in many colors and widths.

  8. kevin_in_denver | | #8

    For my money, vinyl isn't tough enough to use at grade. An errant winter baseball could shatter it.
    Steel with vertical ribs will do the trick:

    As a bonus it's super easy to install, you don't have to attach it to anything. The backfill will hold it in place if it's not too long. Then the siding or a piece of flashing at the top will protect the top edge.

  9. GBA Editor
    Martin Holladay | | #9

    Buried steel will rust.

  10. dickrussell | | #10

    Matt, I just googled on fiberglass mesh and picked one vendor. I spoke with someone there and they had a single roll of 3' wide mesh, about 5 per inch, he wanted to unload, so I got it half price. Before I applied it to the foam, I roughed up the surface a bit with a wire brush, then wiped the foam dust off with a rag. As I worked my way around the house, I found that I didn't want to get too far ahead in applying the mesh, as the sticky coating on one side didn't adhere to the foam overnight. That was ok, and the SBC itself is what sticks to the foam; the mesh is just reinforcement for the SBC.

    I mixed up the SBC with water and C-21 in small batches, keeping the mix fairly stiff. It takes a while to trowel it on and smooth out to my satisfaction. You can't mix too much at once, or it starts to set up before you get the last of the batch on. The cleanup of the mixing tub takes a short while, too. As Riversong stated, the stuff is hard to get off the tools once it has set up.

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