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Cold bathroom walls

| Posted in Energy, Heating & Insulation on November 27, 2002 05:10am

Our bathtub is on an outside wall and in the winter the ceramic tile walls get really cold, making it uncomfortable for my wife and 3-year old to take baths.

I’ll be gutting the bathroom soon to do a complete remodel and would like suggestions on how to “warm up the walls.”  The wall construction is: 2 courses of brick (not frame and veneer), 1×2 on the inside with 3/4″ of fiberglass insulation in between and two sheets of 3/8″ drywall.

I know that using something other than ceramic tile on the new walls will not feel as cold.  Moving the tub to an inside wall is not an option.  I’ve seen different products for warming tile floors, but since the are usually electric, I wouldn’t think they would be safe to use behind the walls in a shower/tub area.

Any suggestions will be GREATLY appreciated.

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Replies

  1. User avater
    BossHog | Nov 27, 2002 05:26pm | #1

    Do you have enough room to shift the tub over? If you have 4 or 5" to work with, you could frame a 2X4 wall behind it, and insulate the wall. But the tub would have to slide out a ways to make that work.

    Regardless of which way you go, insulate UNDER the tub. That will help keep the bath water warmer for a while longer, and will, help a bit. Just stuff some fiberglass batts under the tub while things are torn up.

    Would a part-time bandleader be considered a semi-conductor?

    1. Wolf1Daddy | Nov 27, 2002 06:27pm | #2

      Boss,

      It's a really small bathroom--5x7.  Not much room to move the tub, but maybe I can get a couple of inches and add a 2x2 and a bit more insulation.

      What do you think about foaming the bottom of the tub instead of using the fiberglass?

      1. User avater
        BossHog | Nov 27, 2002 06:32pm | #3

        Foaming with what? Don't think it would make much difference what you used, as long as it was insulation.Have patience - It's important to wait for just the right moment before screwing someone over.

        1. User avater
          jhausch | Nov 27, 2002 11:16pm | #4

          I would guess that spray-in icyene (sp) would be the best for the space available. 

          What about radiant heat backed up with thin foil-faced foam insulation?  I am no expert, but maybe there is a way to use the existing hot water line with some sort of mixing valve and pump?Steelkilt Lives!

          1. Wolf1Daddy | Nov 27, 2002 11:38pm | #5

            I thought about using the existing hot water to heat the wall but couldn't figure out how to do it.  This would work great, especially if I could activate it only when someone was bathing.  Anyone have any idea how to do this?

  2. Frankie | Nov 28, 2002 12:03am | #6

    Bad idea. While you are away one cold winter weekend the pipes could freeze. They are at the end of a run and high up in the structure so that there is little protection from the cold. Also, by the time the shower wall warms up you will already be out of the shower. Don't forget that the wall would not get the hot water until AFTER you turned on the shower.

    Bottom line is you do not have any room to insulate other than the 3/4" foam. Be very careful when rebuilding the wall. You must maintain some type of air space between the brick wall an whatever is laid against it. This is for condensation/ wetness that comes with brick. Use rigid insulation only. The fiberglass type will only retain the moisture and create further problems.

    Maybe building an enclosure that is prefab, made of molded plastic, it will heat up from the shower water splashing against it quicker than a masonry wall would. Less mass = less warming req. It would also give you an additional 1/2" more space for thicker insulation.

    1. User avater
      jhausch | Nov 28, 2002 01:04am | #7

      I agree, if it is just an extra 40 feet of piping in the wall on the way to the shower-head it is a bad idea.  He'd never have a hot shower in the Winter again.

      (like I said, I am no expert - however - )

      My thought was if he could tap off of the existing line, go to a circ. pump, then into a mixing valve controlled by a thermostat. . . the loop in the wall would be circulating as required and the water coming out of the "far" end of the loop would be going back to the HWH.  The water at the shower head would still arrive directly.

      I don't know how the t-stat would control the pump and valve, but if it were left off, then you still have the bursting pipe problem.

      Just a thought.

      Maybe something like this - http://www.radiantec.com/opendirect.htm

      Steelkilt Lives!

      Edited 11/27/2002 6:36:13 PM ET by Jim

  3. CAGIV | Nov 28, 2002 11:04am | #8

    I don't know how this would work on an exterior wall, but I have seen underfloor radiant heating systems used to warm bathroom walls, under a tile wainscoting, but you would have to ask a plumber about the possibility of the lines freezing being so close to the outside. 

    If you take showers at regular times a thermostat with timer can be hooked up to the system to turn it on before you get into the shower in the morning.

    1. Bruce | Dec 12, 2002 08:12am | #9

      I'd investigate one of the electric in-floor radiant heating mats.  Haven't used them myself, but considering it in the tile bathroom floors in our next personal house.  You could size it to lay ander the tub and up the wall behind it.  I spose you could sandwich it between some gree board behind the tub.  Then wire it to a timer switch on the wall.  Turn it on a bit before using the tub, and let the timer turn it off so your electric meter doesn't peg.

  4. grassbur501 | Dec 12, 2002 08:25am | #10

    It wouldn't surprise me to hear that, upon taking the inside layers off the wall, you found that all of it has gotten damp, from condensation or leakage, and thus nearly all the R value is gone. Anything you can do to add to the space between brick and inner frame will be just a little bit more insulation you can add. And definitely go with the rigid foam.

    Mac

  5. TLRice | Dec 12, 2002 05:02pm | #11

    Change the fiber glass to rigid foam and that will almost double the R-value of the insulation. Seal it to the 1x's with caulk to reduce the air leakage and seal the top and bottom plates and penetrations for pipes and wires.

    That would be the easiest change to make. Spray-in eurethane foam would do the same, maybe a little better. Might want to consider installing a heating light fixture near but no over the the tub.

    As far as the tile goes, it only feels cold if you touch it. I like tile for bath areas, but I don't have a 3 year old.

    I have installed in my home several different brands of the electric floor heating systems. The one made by NuHeat comes with a GFCI in the controller because it is intended for bathrooms and the like. This version would probably be suitable for a wall because it is packaged with the heating elements (wires) contained within a thin fibrous mat. A thin layer of thinset, apply the mat, a carefule application of thinset over the mat with a notched trowel and apply the tile.

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