Home Improvement 101: Covering a Hideous Concrete Protrusion

June 30, 2016 8:41 PM

I live in a split level house where the bottom floor is partially below ground. In several areas, there is a concrete protrusion (part of the foundation) that sticks out from the wall, along the floor. The builders covered some of the areas, but not all. I am a home improvement noob. How do I cover these concrete ledges easily?

In the bathroom, the builders erected a ledge/shelf up to a couple inches below the window, which I assume is covering a protrusion. In one room, they covered the ledge along one side but not the other for some reason. At some point I want to finish the other side in that room, but right now I'm working on a closet that just has the ledge along one wall. It's 9.25" tall and 1.5" deep. My question is two part:
1. How do I cover the ledge in the closet in the easiest and most affordable way, since this will never be seen.
2. How do I cover the left ledge in the other room so that it matches the ledge on the right? I'm not sure what exactly I'm looking at.

As to why I'm worrying about the back of the closet: I'm turning it into a craft area and am trying to make it seem as unlike an under-the-stairs basement closet as possible. Also, I'm hoping that sealing up the cracks will help keep spiders out.

Please be as specific as possible in terms of tools, products, and the order in which to do things. I'm an eager DIY-er and am looking forward to expanding my knowledge!

posted by Safiya to Home & Garden (9 answers total)

I would put built in shelving on top of something like the first pic. You could even cover the bottom part with a false front to make it look like cabinetry all the way down. Cabinetry isn't too hard to build, but you do have to take great care in measuring the distances and angles. It isn't likely that the walls are perfectly plumb or square.

Depending on the room and the exact height of the space above your ledge, it could make a decent home theater area. A projection screen could hang above the ledge, making the space seem less wasted. (Or you could do both!)

The second, were it in the back of a closet I would leave as is. If that wasn't an option for subs reason, I'd tear off the drywall, use some foundation sealant on the exposed concrete, build out the studs behind it to a hair beyond the ledge and drywall over it to make a "normal " wall.

Thing is, I don't terribly like covering concrete that is below grade. Being porous, it can invite mold if there isn't a proper vapor barrier. Or worse, there could an intermittent underground stream as one of my friends had in his old house's basement.
posted by wierdo at 9:19 PM on June 30, 2016

In your first photo, the "one room" link, there is a. . . . turd-like object that has apparently been painted over.

If it were me, I'd take more photos, then attempt to remove that . . . turd thing.

There is no universe in which things like that are normal for sealing foundations.
posted by yesster at 9:37 PM on June 30, 2016 [3 favorites]

I can't quite tell from the picture ... is the protrusion your dewatering system? If so, you can cosmetically hide it but you're not going to want to spider-proof-seal it. And yeah, dampness will be a concern.
posted by Eyebrows McGee at 10:26 PM on June 30, 2016

Best answer: They're likely stem walls. I've seen them exposed like this in homes where the basements were finished at some later point. Typically, they're furred out with a couple of 1x lumber strips on each face, top and bottom (use a rotohammer like a Bosch Bulldog and Zamac anchors or another concrete anchor). Then sheath with drywall -- now you have something to screw the drywall to -- and finish like you would any other drywall, with a metal corner bead for the outside corner and tape on the inside corner. Run your baseboards along the new drywall.

I've also seen the top ledges (the horizontal part) covered with wood trim for durability, in which case you'd just use finish nails to attach the trim to the furring strips.

If you go with drywall, I recommend choosing a glossier i.e. more durable sheen of paint as they tend to accumulate dust and it's nice to be able to scrub them clean.
posted by halogen at 11:15 PM on June 30, 2016

Best answer: The easiest way to hide the one in the closet would be not to cover it but to finish it so that it's smooth and paint it the same color as the wall. Use a concrete repair product (like drywall mud, but for concrete -- practice is the key to success) to get a smooth finish, sand it with a power sander, seal it/prime it, paint it. The finishers at work use Silpro Raeco Feather-Spread to get super smooth and even surfaces on vertical concrete that gets no finish other than paint (like in staircases).
posted by halogen at 11:29 PM on June 30, 2016 [1 favorite]

Response by poster: The turd-thing is a bit of expanding foam, the kind you squirt out of a bottle. I don't think it's painted, it's just a similar color to the walls. When I get around to finishing that room there is a lot I need to trim off.

I don't know what a dewatering system is.

We do live in a damp area, but haven't noticed any wetness in the basement.

I'm going to use cement patch on the floor to fix some uneveness, so I think I will have a go at using it to smooth out the protrusion in the closet, then paint it.

Thank you for explaining how to cover it with drywall! That's probably what we'll do in the other room in the future.
posted by Safiya at 6:51 AM on July 1, 2016

You could also build out that wall a few inches with lumber that's ripped so that it sits flush with the concrete, put furring strips over that running floor to ceiling, and then drywall over everything to make the concrete disappear completely. That's how I would do it, if it were my house. Then you'd have a normal-looking wall instead of one with an incongruous foot-high ledge on it. That's how it should have been done originally, in my opinion.
posted by Anticipation Of A New Lover's Arrival, The at 1:43 PM on July 1, 2016

Seconding that they look like stem walls, and halogen is on the money with how to cover them.

But first: if you live in a damp area with a below-grade basement, get someone to hit the exposed parts of the wall and the baseboard with a moisture meter before you start covering anything up. You need to know about your dewatering system, because that will inform how/to what extent you cover these up. You might consider waiting to do a whole lot down there until you've gone through a significant wet spell. Just because you haven't noticed any wetness in the basement doesn't mean it isn't there, or won't be.

Even if there's a decent vapor barrier under the concrete pad, you're probably going to want a dehumidifier, and you may want to consider pulling out that carpet. It will hold any moisture that does get down there, and in case of flooding will wick up moisture into the baseboard/drywall.

Our mid-Atlantic basement is half below-grade, and was "finished" in more-or-less the same way yours appears to be: new carpet, drywall, baseboards, fixtures, new coat of paint. But it was all cosmetic, and a couple crazy wet seasons--during which the carpet got soaked although there was never standing water--forced a complete redo. I eventually tore out all the carpet and the bulk of the (amateurish, lacking a vapor barrier) interior framing, which had significant dry rot. The one time it's gotten wet down there since (we regraded, put in a new sump, added rain barrels) the moisture was gone within a couple hours.

If you're in newer construction with adequate vapor protection and drainage (rather than a retrofit), none of this may be a problem. I would still stick with pressure-treated lumber on any new framing you do.
posted by aspersioncast at 12:15 PM on July 4, 2016

Response by poster: The wall with the exposed ledge in the "one room" picture has a window in it, so I probably won't try to build it up all the way. Maybe just up to a few inches below the window so that it makes a more convenient shelf like is in the downstairs bathroom.

The house was built in 1991, and though some things are a bit sketchy (we're guessing slap dash spec house), we've lived in it for 5 years and haven't had any flooding in the basement at all (knock on wood). There's a bedroom and family room down there that both have wall to wall carpeting, and it's never been wet. I'm pretty sure the downstairs was completed at the same time as the upstairs, the front door opens to a staircase that goes both up and down and the basement area is a significant chunk of the living space. A dehumidifier down there is a good idea, we certainly don't want to deal with any mold or rot.
posted by Safiya at 11:25 AM on July 5, 2016