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To insulate or not to insulate a basement bathroom??

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  • To insulate or not to insulate a basement bathroom??

    I am in the process of doing a basement bathroom.
    It will be connected to an already existing finished basement.

    I have a question regarding what to do for insulation for the bathroom wall on the poured foundation wall. The wall is completely below grade. The sink and toilet will be on the foundation wall. Shower is completely interior. And the pex warer supply pipes that are on that wall are near the bottom third of the concrete wall.

    Originally, I was going to do fiberglass batts in the stud wall cavities.
    Then I did a little research on this topic and found a better way to go is the rigid foam board insulation.....

    Unfortunately, though, I have no way of doing the rigid foam insulation. The stud walls are already up, and are completely fire blocked. So, I can’t even slide the 1/2" Dow Styrofoam behind the studs....

    For what it is worth, the bathroom will have radiant floor heat (Warm Up brand) and a Panasonic Whisper Warm 110 CFM vent fan....so the bathroom will be heated and vented sufficiently, I would assume to remove any dampness....

    Plus, I always run dehumidifiers on both the unfinished and finished parts of the basement in the summer. And my pellet stove is always running in the finished basement in the winter. So the basement is usually around 40-55% humidity.

    Also, I have never got any water through the poured foundation wall that will now be part of the bathroom (knocking on wood right now). Also, one of the previous homeowners put a coat of what appears to be Dry Lock on the wall as well.

    So, this is my question....
    Should I just put some batts in the stud cavities? Or should I just leave it uninsulated?
    If I do fiberglass batts, should I do faced batts toward the warm in winter side? Or unfaced batts?


    thanks.
    mm

  • #2
    Re: To insulate or not to insulate a basement bathroom??

    "warm in winter side" ?
    its a bathroom with a shower so bat insulation no Kraft paper walls and ceiling and plastic vapor barrier walls and ceiling.

    Also you'll need to install an approved bathroom vent. It MUST vent to the outside (not in a wall or stud cavity or between floor joists.)

    Comment


    • #3
      Re: To insulate or not to insulate a basement bathroom??

      Thanks for ther help thus far…..
      still researching….

      I found this at Lowes:
      http://www.reflectixinc.com/basepage.asp?Page=DIY+Wall+-+Masonry&pageIndex=562

      I can staple it right to the studs, which would leave an air pocket between concrete wall and studs, then go over it with sheetrock.

      Anybody have an opinion on that product? Anybody forsee any problems with it?

      Comment


      • #4
        Re: To insulate or not to insulate a basement bathroom??

        What’s amazing to me is that there are so many differing opinions (on this forum and other forums that I have asked the same exact question)....frustrating for a homeowner.
        Yes vapor barrier, no vapor barrier….
        Faced insulation, unfaced insulation…..

        I am wondering though…...... would the safest option to be leave it uninsulated??

        That way if I do get any moisture, it can dry out on its own and I wont have to worry about any insulation retaining moisture…
        Pipes will not freeze….so that’s not an issue….
        Like I said, the bathroom will have radiant floor heating and a Panasonic 110CFM vent fan (with the heater)....
        Plus, I always have two dehumidifiers running in the basement….along with my pellet stove in the winter.
        So the bathroom shouldn’t be damp…

        Unless someone can give me an overwhelming reason why I shouldn’t leave it uninsulated, I may go that route…

        Thanks again.
        mm

        Comment


        • #5
          Re: To insulate or not to insulate a basement bathroom??

          Here are a few pics of what my wall looks like now.

          The gap between the back of the studs and the concrete wall is no more than 3/4”.
          Plus, it is all blocked off and fire foamed, so I can’t slide some 1/2” rigid foam behind it.
          Plus, as you can see, I have all the plumbing and wiring running through the studs…so not much room in the stud cavity.

          Like I said, I think I may go the no insulation route…...

          thanks for the help….
          mm
          Attached Files

          Comment


          • #6
            Re: To insulate or not to insulate a basement bathroom??

            I would do my best to get some ridgid foam in there. Even if it means cutting the foam up so that it fits between the studs.

            Check out this link:

            http://www.buildingscience.com/docum...wner_resources

            Comment


            • #7
              Re: To insulate or not to insulate a basement bathroom??

              "Unless someone can give me an overwhelming reason why I shouldn’t leave it uninsulated, I may go that route"

              you said it yourself "I always have two dehumidifiers running in the basement"

              now add a full bath in the mix and what ya think you'll get?

              the vapor barrier goes on the inside of the bathroom over the insulation and i see no problem at all working fiberglass in and around your plumbing and electrical.

              also i don't see any PT on the cement that can be trouble later on if not sealed right.

              Another good reason to properly insulate that bath is condensation. cold wall and hot shower the shower steam/vapor contacts that cold wall where the foundation is and you have all sorts of water on the floor, inside the wall, and wet Sheetrock. and mold just LOVES wet Sheetrock.

              Never mind the shiny space age "insulation" that you posted a link to , that stuff is worthless at best. go with 3 1/2 inch fiberglass and 6 mil poly with poly adhesive at the corners, ceiling, and along the floor plate.
              Last edited by Arthur96; 04-05-2010, 05:01 PM.

              Comment


              • #8
                Re: To insulate or not to insulate a basement bathroom??

                I would NEVER use fiberglass batt insulation against a foundation wall. Concrete is porous and the fiberglass will wick any moisture from the concrete, thus causing a mold situation.

                If you leave it uninsulated and put drywall up (even water resistant drywall) the back side will absorb moisture from the foundation wall (remember concrete is porous).

                You definitely should insulate the foundation wall, and the water supply pipes need to be insulated to guard against the possibility of freezing. While PEX is flexible it can burst if the water in the lines freeze. And where is your vent stack located? If it is on the foundation wall it needs to be insulated as well.

                I would highly recommend spray-in foam insulation. I use Envirotite Injection Foam for such applications with great success. Here is the link to their web site: http://www.envirotite.com/spray-foam...njection-foam/

                If you're set on using fiberglass insulation, you need to place the vapor barrier against the foundation wall. Adhere it to the wall with construction adhesive. Then you can place batts of foil-faced fiberglass insulation in the stud bays, with the foil facing in. The most important thing is to keep the insulation dry at all costs, to prevent mold. You must also tape/seal around any outlets & switches to keep moisture from seeping into the insulation from these openings.

                Personally, when I do bathrooms, I use spray-in foam with 2 layers of 3/8" greenboard. The 1st layer with the seams running vertically. I then tape and mud the joints & screws. I then place the 2nd layer with the seams running horizontally, again mudding and taping with fiberglass mesh tape and synthetic joint compound (it repels mold). Also I use exterior deck screws (NOT std. drywall screws) as they do not rust and therefore is not a breeding ground for mold.

                As was stated in an earlier post "you must use a vent fan. . .and it must be vented to the outside". The fan should be placed just outside of the shower stall so that the hot moist air (steam) can be evacuated quickly keeping as much of the steam from the rest of the bathroom as possible.

                Hope this helps!
                Last edited by CARPENTERDON; 04-20-2010, 03:58 AM.
                Dimensional Carpentry & Custom Woodworking
                Historic Renovations, Restoration, & Custom Log Homes


                I Beat The Competition Hammersdown!

                Comment


                • #9
                  Re: To insulate or not to insulate a basement bathroom??

                  lol look if he gets so much water in the basement that it will "wick" into the insulation then hes got more problems than weather to insulate or not. roll or spray on some drylock "IF NEEDED"

                  what you describe as your preferred method of doing drywall to me is ridiculous. when i was doing some industrial commercial work we used to double up on drywall ONLY to create a particular timed burn rating and NOT for any waterproofing or mold prevention which it wont do at all.

                  they have a drywall product on the market now with no paper (see its the paper in the drywall that mold likes to eat.....even green board which is long been proved NOT to be water resistant at all)

                  Comment


                  • #10
                    Re: To insulate or not to insulate a basement bathroom??

                    Arthur96 wrote: ". . .they have a drywall product on the market now with no paper (see its the paper in the drywall that mold likes to eat.....even green board which is long been proved NOT to be water resistant at all)"
                    I don't know where you're getting your facts from, but greenboard ("greenboard" is the generically used term. The new stuff is blue or purple, but everybody knows it as greenboard) IS water resistant, but NOT waterproof. It is required "by code" (where I live) to be used in all bathrooms, basements, and finished garages (anywhere that has moist, damp or humid conditions or the possibility thereof). And, I'm not talking about the greenboard itself, I'm talking about water vapor getting in behind (into the wall cavity). I've seen it hundreds of times, if not more, especially in bathrooms. The drywall is fine on the exterior surface, it's the backside and insulation that gets the mold.

                    Even though the greenboard is taped, mudded, primed, and painted, water vapor does seep into the openings around light fixtures, outlets & switches, ceiling fans, etc. Keeping water vapor from getting in around these protrusions helps immensely against mold infiltration.

                    AND, using two-layers of 3/8" greenboard in bathrooms is an extra measure of prevention against mold that does work, whether you want to believe it or not. Doubling up is not just for fire rating (which I am very familiar with).

                    Unlike most contractors, I tape, mud, seal, prime, and paint all the greenboard behind one-piece or mount-in-place shower stalls. If it is to be a tiled shower stall I use cement backer.

                    I do every job to code +2 (2 steps above code) standards. Been doing it this way for 28+ years. Guess what, my jobs stand the test of time and I don't have to "go back" to fix any mistakes or problems! My customers are very satisfied with my work and I get many, many referrals from them, so I must be doing something right?!

                    If I wouldn't live with the way something is done, I don't expect my customers to live with it either.

                    Contractors like you, that have the "that's unnecessary" attitude are the contractors that I have to go and clean up after and fix their mistakes. Time and time again, happens all the time!
                    Last edited by CARPENTERDON; 04-20-2010, 05:03 AM.
                    Dimensional Carpentry & Custom Woodworking
                    Historic Renovations, Restoration, & Custom Log Homes


                    I Beat The Competition Hammersdown!

                    Comment


                    • #11
                      Re: To insulate or not to insulate a basement bathroom??

                      contractors like me? listen bub 1 i doubt very much that you have been doing this work for as long as you say. I on the other hand I grew up in it.

                      I've built at least 2 dozen Custom homes, and not subbing for somebody else.countless remodels and yea a lot of drywall and tile work. I know what works and i know whats bull. if you like your way well that's fine but before you go charging a customer double for building whatever it is your going to build because you have to buy double the materials and double the labor try giving them a price for doing the job the regular non anal retentive paranoid way and then your supposed better indestructible way and see which one they pick.

                      and its guys like YOU who I have to go behind and fix stuff for and its always a PITA because of the F%#$^d up way you paranoid guys do things
                      Last edited by Arthur96; 04-20-2010, 10:12 AM.

                      Comment


                      • #12
                        Re: To insulate or not to insulate a basement bathroom??

                        Paranoid??? Are you kidding?!

                        So, it's paranoid to give a customer the BEST job you can? I grew up in this business as well. Started with my uncle, whom is a master carpenter and woodworker, at the age of 10, and been doing it ever since! , At the age of 12 I started learning design, building codes, and structural eng. from my mom's boss; a Registered Architect and Structural Engineer of 58 years (currently). Worked on and off with him over the last 25 years on multi-million commercial projects (hospital wing additions, GM mfg. plants, etc.), so I would say that I have a pretty good grasp of the industry! And I DON'T charge extravagant amounts on any of my jobs. I am NOT a price gouger!!!

                        As well, I have been building custom milled log homes since 1991. I do custom millwork, cabinetry, mouldings, etc.

                        NEVER in all the years that I have been in business have I had a single complaint from a customer about my prices, my work (as in being over built), nor about my work ethics or principles.

                        I believe that all of my clients should receive the a job done to the best of my ability, that will stand the test of time, and is done at least 2 steps above code requirement to ensure that the job will last and be above their (the client's) expectations!!!

                        Now, if that's a bad thing, well. . .I don't know what to say?! And, if you think that is being paranoid then so be it, but I sleep with a clean conscious and conduct my business with one as well!
                        Dimensional Carpentry & Custom Woodworking
                        Historic Renovations, Restoration, & Custom Log Homes


                        I Beat The Competition Hammersdown!

                        Comment

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