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Community and Q&A

Feedback on This Plan for Insulating Around Basement Plumbing

thegiz | Posted in General Questions on

Hi I’m hoping there is nothing wrong with my idea as it would just make life easier for me. I want to insulate my basement wall by glueing eps foam right to concrete and then glueing my drywall directly on top. I do not plan to run any wires in wall. All my wires are running in metal conduit now. If I want to hang anything like a picture frame I will use adhesive hooks or tape. There is my Pvc drain line and my main water line on this wall. Instead of creating boxes and access panels I think I just want to recess into the wall basically insulate around it. Any harm in doing this or violation? I’m not looking to make the cover of hgtv at the moment and I can simply always box out after the fact. Will it just look weird, not sure if I ever saw this on a wall. Picture attached, I’m basically just going to try to square the wall around everything so I have clean edges with plumbing recessed in wall. Is this somehow a code violation? I know I would lose some heat in this area but it’s a small amount of the entire wall. My reasons for doing this is: future renovation will not require ripping out any insulation to get to plumbing, I can replace any plumbing easily, I do not need to add 4-5 access panels as I have my main valve shut off, clean out, an instant water heater, and another shut off valve in this wall.

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  1. charlie_sullivan | | #1

    I'm not sure I completely understand what you are proposing to do at the pipes, but here's the potential concern. If you have most of the wall insulated, but a 4-in strip open to the interior air, the insulation everywhere else will keep the concrete wall colder than it is now without insulation, and the inside air will be warmer than it is now, and likely have a little higher moisture content than it does now even if the relative humidity is the same or lower than it is now. That could result in condensation on the concrete wall where it is not protected from the inside air.

    It looks like you have room to get some thickness of foam behind most of that plumbing and I would definitely recommend doing that. Near grade and above grade, that will also be useful for protecting from freezing.

  2. thegiz | | #2

    Sorry I worded that question terribly. Yes you are right in that I could slip insulation behind some of the plumbing. I could probably spray foam around any missing areas. I guess what I'm really asking if I could insulate and drywall around the plumbing so it's not recessed but in front of the insulation and drywall. Basically exposed rather than boxed in and covered but thinking about it would be difficult in areas like the shut off valves that are close to the wall. Anything would also need a layer of drywall for fire protection.

    I also suppose what I'm asking if if you need furring strips or studs if wiring is not being run through the wall.

    1. charlie_sullivan | | #3

      Oh good, then your question isn't as hard as I thought. as far as I know, there is no code requirement to cover plumbing. PEX should be protected from UV, but otherwise, hiding it is just for aesthetics.

      As far as the other question--can you just attach foam to the wall and drywall to the foam with glue and skip using any wood or screws, I don't see anything wrong with it and have wondered why more people don't do that. I'll be curious what others say. You will need some way to hold it in place while the glue dries, and whatever you rig to lean against the wall to hold it might only work for one section at a time, so perhaps that's the limitation: you'd need to do one section, wait for it to dry, etc., perhaps taking weeks to complete, which is fine for a DIY project but not so great for a professional.

  3. Expert Member
    PETER G ENGLE PE | | #4

    Your approach can work, but Charlie has hit on the biggest challenge - finding the right adhesive and getting it to stick reliably for the life of the wall. There are certainly adhesives that are strong enough to do the trick without any studs or strapping to help. Preparation and application conditions are important. You might want to try one of the various types of washer-headed foam anchors to help hold the foam in place while the glue dries. Definitely try to slip some insulation behind the pipes and spray foam the gaps. Set the foam directly on the floor to provide some support, but space the drywall up 1-1/2" or so with lumber spacers to keep it out of the flood zone for small floods. Use moisture tolerant drywall or even fiberglass faced drywall. Basements are damp and/or wet, and it's not going to be easy to replace the drywall once everything is glued down. Use something durable.

  4. Expert Member
    BILL WICHERS | | #5

    I would insulated right up to the pipes, and slip some thin rigid foam behind them if you can. Basically do the best you can to cover as much concrete as you can and call it good. I like tapcons and big plastic "insulation washers" to secure the foam to the wall.

    Regarding future maintenance, what I would do is just cut the foam panels so that the ones in the immediate area of the pipes have sections that could be removed. The advantage to tapcons is that they can be removed and reused (although you have to be careful, they tend to strip out the holes). Think of the foam insulation a bit like drywall: you can always rip a hole in it to do maintenance and replace/patch it as needed when you're done.


  5. Expert Member
    NICK KEENAN | | #6

    With pipes in an insulated wall you have to be careful not to put the pipe in a part of the wall that gets below freezing. The safest thing is to insulate only between the pipe and the exterior, no insulation on the interior side, so the pipe will be close to room temperature. In basement walls there is a little more leeway because part of the wall will be below the frost line.

    Consider putting a piece of 2x wood at the top of the wall from the edge of the mudsill to the edge of the insulation. Then you can hang the drywall from the wood. Still use glue on the foam and drywall, but this way the weight of the drywall isn't on the glue. This also provides fireblocking at the top of the wall, which may be required. And it allows you to keep a gap between the bottom edge of the drywall and the concrete floor, which helps keep it dry, without putting a lot of weight on the glue.

    You also end up with the bottom of the joist bay covered with flat wood from the rim joist to the interior wall. Put a piece of foam board over that and you're all set.

  6. tommay | | #7

    First thing I would do is correct that plumbing. You have 3" piping heading out the foundation when it should be 4", though it may be tough to change it now. There should be a 4 x 3 wye there with a full size cleanout. What is that pipe coming in from the left? No cleanout there either and it ties into a t-wye instead of a wye. What about that abandoned t-wye? If you correct the drainwork, you may be able to arrange it so you can suitably insulate it.

  7. thegiz | | #8

    The left pipe is for a washer machine. I don't know much about plumbing, not my strength so I will have to look into it.

    The 2x on top would work for half the wall but the sewage pipe also runs along the top of the wall for most of it's length. I was also considering gluing or attaching 2inch eps to wall and then using 2x4 on the flat furring strips every 24 inches on center. Then between furring strips gluing 1.5 inch eps making the wall flat and my drainage pipe would be recessed or equal with wall making everything flat. It would leave me with a 3.5 inch insulated wall. Furring strips would hold first layer of eps and drywall firmly in place. The eps between furring strips would be held in by drywall and glue. On bottom I would cut my furring strips at least 2 inches up from floor and slip in a piece of eps on bottom. After leaving a 2inch gap for drywall use the bottom of furring strips to nail in pvc bottom trim. My drywall would be off the ground. I could still use a 1x on top in line with everything but I could go thinner since it is not supporting the drywall anymore.

    I don't know if it is worth saving the interior room but since the bottom of pipe and top runs along the wall I would have a strange box out to gain maybe 2 inches of wall space. Not sure how much of a difference that makes in a small room but I'm thinking minimal and a flat wall would look better. I was trying to make this easier but it seems like getting everything to stay in place with glue without wood is complicated with a obstruction on top and bottom of wall. On opposite wall is nothing so maybe I can just glue there.

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