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A while back I tore down a deck and did a bit of landscaping, exposing quite a bit of the concrete foundation of my house. I have vinyl siding above and around this portion of concrete but would like to extend it to cover up the newly exposed concrete portion. The vinyl siding that around the concrete portion that I want to cover up is attached to an OSB board that's attached to the framing of the house. As a result, the OSB protrudes about a half inch farther out than the concrete. In effect, I would need to add a bit of spacing between the concrete and the siding.

My initial thought was to attach whole sheets of 1/2" OSB around the portions I want to add siding to directly to the concrete using concrete anchors. However, as is common with foundation pours, there's vertical protruding "lines" of concrete that results from the gaps between the panels used during a foundation pour. While those can be grinder down, the paneled sections aren't exactly perfectly level with each other, either. I'm also running into the problem of only having a 1/2" of room for driving nails in.

My other thought was to use 2" x 1/2" furring strips with 4" wide strips around the edges, attaching them using concrete screws. Significantly easier to attach than a whole OSB panel. In between the strips the plan would be to add 1/2 XPS foam. The foam is a bit easier to work with to handle the unevenness in the concrete. However, there's still the problem of only having a 1/2" of OSB to work with. Going this route, I'm not sure what the spacing should be between furring strips (couldn't find any online resource that had a recommendation).

It seems like any way I do it, I'll have to be pre-drilling holes into the concrete for whatever anchor I use to attach the siding. If I do pre-drill, what kind of anchors should I be using? Galvanized nails? Concrete screws? And if at the end of the day I'm fastening the siding to the concrete, is there really a need for OSB or can I just use 1/2" XPS foam throughout? I'm guessing I'll need to use some OSB to properly attach flashing and maybe a bottom starter strip but I'm unsure about everything in between.

Thanks

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  • I have somewhat the same problem...entrance room is concrete, rest of the house is crawlspace with plywood. Took the decks off to replace them with padio. I also thought of putting vinyl siding on but decided against it. The siding on the entrance room was always a little lower than the rest and I already had issues with mice getting behind the siding and crawling up in it. That was when the deck was still there. I settled for paint for both, the crawlspace and the concrete. That way I don't have to deal with critters. It is called Deck Correct by Cabot, comes in differed colors and can be use
    – Lucy W.
    Oct 23, 2018 at 20:02

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OSB has no business against concrete. Use treated lumber or plywood for furring.

I'd probably go with folding foam board and skip the furring strips. Use concrete screws for anchoring the siding.

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  • I failed to mention that I was planning on using house wrap directly on the concrete and put the OSB over that.
    – vlozko
    Oct 23, 2018 at 3:21
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    Housewrap is not impermeable. Your OSB will be constantly damp and will swell and disintegrate. At least use plywood, and ideally treated plywood.
    – isherwood
    Oct 23, 2018 at 20:34

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