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Thread: Securing plywood to poured concrete basement wall

  1. #1
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    Securing plywood to poured concrete basement wall

    I have a 23 year old house with a below ground poured concrete basement. I'd like to put a few sheets of plywood on the top half of the wall to hang shelving and cabinets. There are currently no moisture issues, other than a VERY small infrequent leak around a tiny 1/4" pipe that is coming through the wall. It only happens in periods of heavy rain. I don't even know what the pipe was for, it has been cut at the wall, and pinched shut. The leak is not from the pipe itself, but the seal around the pipe. I'll probably end up digging it out a bit and re-sealing it. Not a big deal.

    I plan on putting the plywood up in one of 2 ways. First, I will put a simple moisture barrier between sheet the concrete and plywood. Then I will either screw through the plywood directly into the concrete, or add vertical spacers (3/4" thick and about 2" wide) to the concrete, and attach the plywood to this. Does anyone see a problem with either method?

  2. #2
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    Suggest you might consider just some horizontal wooden cleats to hang those cabinets. Could use several Tapcon anchors or other concrete lag screws counter-sunk to fasten wall cleats (using a level naturally). Cut one edge of each cleat length to a matching bevel and fasten that bevel downward to the back of your cabinets nearest the top.

  3. #3
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    Quote Originally Posted by Morey St. Denis View Post
    Suggest you might consider just some horizontal wooden cleats to hang those cabinets. Could use several Tapcon anchors or other concrete lag screws counter-sunk to fasten wall cleats (using a level naturally). Cut one edge of each cleat length to a matching bevel and fasten that bevel downward to the back of your cabinets nearest the top.
    I had considered this, but I would like to have the full plywood sheet available to attach other small shelves or items to the wall.

  4. #4
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    My recommendation...don’t bother with a vapor barrier. It’s never a good idea to try to control moisture from the inside and trapping any residual moisture between the concrete and plastic sheeting is just going to give you a place to breed mildew. I would recommend furring just to maintain circulation behind your plywood but if you start to see moisture issues, your solution is on the outside
    is the space conditioned? Adjacent to conditioned? Is it completely below grade or walk out basement? In N Ga I am assuming you have at least a couple of above grade exterior walls... unconditioned space is going to be subject to exterior conditions and humidity levels will vary. Ventilation / circulation or even dehumidification systems are far better ways of dealing with humidity changes. Plastics and barriers on the inside unfortunately trap more moisture than they prevent.

  5. #5
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    Quote Originally Posted by Carl Baker View Post
    My recommendation...don’t bother with a vapor barrier. It’s never a good idea to try to control moisture from the inside and trapping any residual moisture between the concrete and plastic sheeting is just going to give you a place to breed mildew. I would recommend furring just to maintain circulation behind your plywood but if you start to see moisture issues, your solution is on the outside
    is the space conditioned? Adjacent to conditioned? Is it completely below grade or walk out basement? In N Ga I am assuming you have at least a couple of above grade exterior walls... unconditioned space is going to be subject to exterior conditions and humidity levels will vary. Ventilation / circulation or even dehumidification systems are far better ways of dealing with humidity changes. Plastics and barriers on the inside unfortunately trap more moisture than they prevent.
    Yes it is walk out basement, but this room has basically 2.75 walls fully below ground level. One wall is a shared interior wall, and the other is only partially at ground level.
    The shop room is not conditioned, but I run a dehumidifier, and the rest of the basement is conditioned. Furring strips w/o moisture barrier it is, then. Thanks.
    Last edited by Joey Stephenson; 11-21-2017 at 4:06 PM.

  6. #6
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    Quote Originally Posted by Joey Stephenson View Post
    Yes it is walk out basement, but this room has basically 2.75 walls fully below ground level. One wall is a shared interior wall, and the other is only partially at ground level.
    The shop room is not conditioned, but I run a dehumidifier, and the rest of the basement is conditioned. Furring strips w/o moisture barrier it is, then. Thanks.
    Good luck! With conditioned space adjacent and a dehumidifier running I donít think youíll have any issues. I have essentially the same set up although it sounds like more of mine is above ground. Yours should stay a little warmer in the winter and cooler in the summer!

  7. #7
    Check your local/state building codes to be certain on what to do with regards to barriers, they usually are quite clear. In Minneapolis, in my basement, I had to put plastic sheeting between the poured concrete and the wall studs(untreated wood touching concrete is a no-no in most codes, especially below grade) and then I had to put a vapor barrier between the drywall and the studs (up here, the temp can drop in a wall such that the dew point & condensation happens in the middle of the insulation).

    Point is, if you are going to do that kind of work, especially in your home, do it right and to code, otherwise you will be sorry when you sell.

  8. #8
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    Quote Originally Posted by Andrew Seemann View Post
    Check your local/state building codes to be certain on what to do with regards to barriers, they usually are quite clear. In Minneapolis, in my basement, I had to put plastic sheeting between the poured concrete and the wall studs(untreated wood touching concrete is a no-no in most codes, especially below grade) and then I had to put a vapor barrier between the drywall and the studs (up here, the temp can drop in a wall such that the dew point & condensation happens in the middle of the insulation).

    Point is, if you are going to do that kind of work, especially in your home, do it right and to code, otherwise you will be sorry when you sell.
    Great advice. I'll check on that first.

  9. #9
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    Quote Originally Posted by Andrew Seemann View Post
    Check your local/state building codes to be certain on what to do with regards to barriers, they usually are quite clear. In Minneapolis, in my basement, I had to put plastic sheeting between the poured concrete and the wall studs(untreated wood touching concrete is a no-no in most codes, especially below grade) and then I had to put a vapor barrier between the drywall and the studs (up here, the temp can drop in a wall such that the dew point & condensation happens in the middle of the insulation).

    Point is, if you are going to do that kind of work, especially in your home, do it right and to code, otherwise you will be sorry when you sell.
    Andrew,
    All good points, particularly the use of treated wood in contact with concrete. Thatís certainly true of structural framing and I do think most codes agree on that. Treated furring would be a good idea.

    As for vapor barriers, I donít doubt that local codes in some areas required it but I have to believe they have removed the requirement or will be removing it. Fact is that you have condensation form wherever hot meets cold and vapor barriers donít prevent that. What they do prevent is effective inward drying from you HVAC or dehumidifier. Sandwiching a wall in vapor barrier keeps insulation and building materials in the wall wetter longer. Ideally there should be waterproofing and insulation / thermal break on the outside of the basement wall. There is debate and I am by no means saying that you did wrong by following your code but I would make any considerations I could to satisfy code and avoid installing interior vapor barrier.

  10. #10
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    Sounds good, I'll definitely keep that in mind.

    If I use tapcon screws to mount the furring to the wall, is it worth putting some silicone or other sealant into the hole before driving the screw in? Or is this just overkill?

  11. #11
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    I say overkill on a poured concrete foundation wall. If Water makes it far enough to be stopped by the sealant, you have bigger issues!
    Just in case someone is watching and extrapolating, I would advise otherwise if you had a concrete block foundation. They will get moisture in unfilled cells and fasteners through it can wick moisture and give you fits.

  12. Hey Carl,

    It is interesting how much local climate affects how you build. I haven't lived in the South, but from what I understand, the big problem there is the humidity on the outside of the house relative to the A/C inside of the house, and that houses rot in the summer outside-to-in from the warm humid air hitting the cold surface of the interior wall. I suppose in that case, an interior vapor barrier is quite problematic.

    Up in the frozen North (this is exaggeration, Minnesota gets periods of summer where the weather is actually hotter and more humid than Florida, we just don't get it for 6 months straight), we have the opposite problem. Our houses rot in the winter because the warm humid interior can condense within the wall on the outside sheathing or in the insulation--the temp difference between inside and outside can be between 50 and 100 degrees in winter. Here the interior vapor/infiltration barrier is considered the norm. It probably would be difficult to find a building inspector here that would pass a house without a layer of poly between the drywall and the studs of an exterior wall. My guess is that the stopping infiltration of cold air is the main benefit though.

    I think some of the approaches are changing, though. I'm seeing some new houses wrapped with rigid insulation on the outside, which to me is a problem because the wall can't dry to the outside. Hopefully there is some kind of compensation for it, or maybe the idea is that the insulation is thick enough to keep the stud side above the dew point. Or maybe they will just rot away. Hard to say.

    I have always wondered what the Missouri's and Ohio's of the world do, where it is hot and humid in the summer, but relatively cold in the winter. Maybe neither is extreme enough to cause problems.

  13. #13
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    Very true Andrew... I wonít claim to have experience up there and itís a fair point that you design to your own extremes. Condensation happens on the warmer side and down here thatís outside of the building envelope for 8-9 months of the year. Up there is certainly a different animal

    Joey just wants to hang a sheet of plywood, and he has probably already done it while you and I went back and forth... however, I do appreciate the insight!

  14. #14
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    Quote Originally Posted by Carl Baker View Post
    Very true Andrew... I won’t claim to have experience up there and it’s a fair point that you design to your own extremes. Condensation happens on the warmer side and down here that’s outside of the building envelope for 8-9 months of the year. Up there is certainly a different animal Joey just wants to hang a sheet of plywood, and he has probably already done it while you and I went back and forth... however, I do appreciate the insight!
    LoL.. Havent done it yet, but since I'm using furring strips and laying the sheets horizontally at the top half of the wall, it really wont matter anyway. There is plenty of ventilation in the design, and it will be very easily removed if need be.

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