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I recently had my basement framed/rocked/finished, and stupidly told the contractor to leave one small wall unfished. That decision came back to bite me as I now want to finish that wall... It's a short little wall at the bottom of my stairs thats 9' long, and just under 9' high and the contractor wants $500 to do the job. That seems way high for the amount of work to be done but I understand his reasoning in that they would need to be back so many times from start to finish, etc.

So I'm going to tackle this short little wall myself.

I want to hang the few panels of 5/8" drywall on a concrete wall without framing it ahead of time (due to timing, amount of wasted space if I were to frame it out). I have some leftover pieces of RC2 Sound Channel (typically used for sound proofing but I was told would work fine here..) that I'm planning on going directly into the concrete with. And then hanging 5/8" fire-rated drywall on it.

I'm using tapcon's to hold the RC2 to the concrete. The RC2 will give a gap of 1/2" from the concrete wall. 1/2" from the RC2 plus 5/8" drywall equals 1 1/8" total distance.

I know the rule of thumb is 1/3 of screw into material, 2/3 into the backing support, but I can't go very deep due to the concrete being 1/2 away from the back of the panel. So with 5/8" drywall will the 1" screws be sufficient to hold the panels? Should I just add more screws to compensate? Good idea? Bad idea?

Thanks

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  • Do a test run before affixing anything to the wall. Shoot the screws through the drywall and into the metal and try to pry it off. The amount of effort you exert should give you an idea if the screws will support the panels.
    – ojait
    Oct 16, 2015 at 23:58
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    Is this on an exterior wall where moisture can pass through to the backside of the drywall?
    – Jack
    Oct 17, 2015 at 3:54
  • Yes it's an exterior wall, but a few years ago in anticipation for finishing the basement I sealed all the walls with Dry-Lok (which is akin to painting with toothpaste..). Further, just on the other side of this wall outside is the front porch which is poured concrete and then the front yard slopes away toward the street (back of house has slightly higher elevation than front). We had some pretty major rainstorms earlier this year and the only water issue we had was on a different area where a radon mitigation exhaust vent was not properly sealed.
    – Josh Weatherly
    Oct 19, 2015 at 15:32

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The 1" screws will work fine. It is going in a metal stud, where the metal is less than a 1/16" thick. The screw will only need to penetrate the metal far enough to get the threaded section of the screw past the tapered point, after that, there is no improvement in holding. As mentioned in another answer, DO set the head of the screw JUST below the paper surface. DO NOT break through the paper facing. You will greatly reduce the holding power of the screw head. This type of drill bit tip will reduce that problem. It needs a firm push while driving the screws to insure they stop below the surface. The screw tip does the rest.

For a wall install you will only need the standard amount of screws, one at the top and bottom edge of each stud, and 3 spaced equally in between the top and bottom screws, 8" on the ends. If you use drywall glue, you can use less, not much less, IMO. I have seen the edges done and one in the middle with a few on the ends when glue is used. Gravity is your enemy here, not the wind from one side or the other trying to push it off the wall. If it was a ceiling install 5 or 6 screws in the center would be my recommendation, unless glue was used.

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  • This is what ended up doing, the 1" screws appear to hold it very well. I might have gone a little overboard, but that just means a little more mud work for the added security that the wall won't fall down. The drywall setter bit I got was a little tricky to get the proper depth but after a few screwups worked great. Thanks for the input!
    – Josh Weatherly
    Oct 19, 2015 at 15:39
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yeah, you should be alright with the 1 inch drywall screws. The optional way to fasten any drywall is to have screw head slightly dimple the drywall paper (not penetrate or damage the paper) so as to have a depression for the joint compound. It wouldn't be a bad idea as you noted to use extra screws. I believe the fastening method is 6 inches along the edges and 8-10 inches in the field. As an alternative suggestion you could install 3/4 inch plywood strips behind the soundproofing strips. The extra 3/4 inches would allow a 1 5/8 inch screw.

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