Insulate a Bathtub?

Discussion in 'Shower & bathtub Forum & Blog' started by BS, Feb 18, 2007.

  1. BS

    BS New Member

    Messages:
    50
    Location:
    Central Ohio
    In the course of my bathroom remodeling research the past month or so, I've come across only a couple references to stuffing fiberglas insulation in the voids around the tub: one was to cut down on tub noise, the other to retain heat.

    How many of you pros do this? Are there any tricks for maximum effectiveness? Are there any potential problems to consider (like what happens if the insulation gets wet from a leak?)

    My tub (Swanstone Veritek) is already permanently installed, but I have access to the voids because I haven't installed the drywall or Swanstone wall panels yet.

    - Bernie
  2. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    It can't hurt, the cost is minimal, and there is no negative to it so go for it.
  3. leejosepho

    leejosepho DIY scratch-pad engineer

    I am no pro, yet I would say the same as Cass. And, I will probably do that at least at the back of our new tub where it sits next to an outside wall.
  4. dense foam

    if you don't like the noise the tub walls make now (if it feels hollow or flimsy, when you are in the tub), then you'll need denser stuff than fiberglass. Something like polyisocyanurate foam (spray-on Great Stuff) which makes a bond to the tub wall. Combine that will some rigid foam scavenged from anywhere. Or you could press the soundproofing kind of batts that go between studs, tight.

    For heat insulation anything is good if it blocks empty air from moving. Bubble wrap is good. Foil faced anything is good too. Fiberglass is good there since no big air currents or pressure there.

    david
  5. Randyj

    Randyj Master Plumber

    Messages:
    1,047
    Location:
    Alabama
    The pic posted below is from a recent tub replacement that I did for a customer. The back wall is against the kitchen. The end wall on the right is against the outside wall. I'm not an expert on insulation but this looked like a really good job done about 25 years ago.
    Pic was taken after I removed the old fiberglass tub.

    [​IMG]
  6. Randyj

    Randyj Master Plumber

    Messages:
    1,047
    Location:
    Alabama
  7. Dan Pick

    Dan Pick New Member

    Messages:
    62
    Location:
    Speedway, IN
    Yes Insulate

    For the cost of a roll of unfaced insulation I think it makes good sense. I have insulated enamaled steel tubs in (2) homes I have owned in the past and it makes for a quieter and warmer tub.
  8. condodweller

    condodweller New Member

    Messages:
    4
    Yes - I recently insulated my 2 new tubs (Kohler Sterling) and I noticed a huge difference. The bath water stayed warmer longer, and the tub itself was not as cold. These are both on interior walls.

    In addition, the noise was noticeably quieter, but not as quiet as if I had used sound proof insulation.
  9. bctile601

    bctile601 In the Trades

    Messages:
    12
    Location:
    Johnson City, NY
  10. BS

    BS New Member

    Messages:
    50
    Location:
    Central Ohio
    Sound Levels

    Brian -- I have no experience with that type of tub. But I can't see why you couldn't or shouldn't insulate it. Any cavity resonates sound, and insulating it cuts down on sound transmission.

    Everyone -- Based on your answers to my question, I insulated my tub the other night. I stuffed fiberglas insulation around the tub (already installed) and I could tell the difference just by tapping on the walls of the tub.

    I actually took before and after sound level readings of a straight stream of water coming out of the shower stem into the tub. :D It wasn't a rigorous scientific comparison by any means, but I wanted to get a sense of the sound-deadening capacity of the insulation. The background sound level reading AFTER insulating was about 3.5 decibels (dbA) higher than it was BEFORE insulating, but the AFTER reading with the shower on was about 2.5 dbA lower than it was BEFORE. These differences were fairly consistent among the various test locations in the bathroom and hallway.

    This may not seem like a lot, but decibels are on a logarithmic scale. My decibel math is very rusty, but basically this means that a difference of 3 dbA represents a doubling or halving of sound intensity.

    Insulation works! Thanks for your input.

    - Bernie
  11. The old college try

    The old college try Engineering Technician

    Messages:
    104
    Location:
    MO
    I'm actually at the same place you were. I'm about to install my tub and I'm contemplating insulating around it with fiberglass. I stayed in an apartment this past summer that had a plastic tub and the noise from the shower was unbearable. I think that everyones contributions and your final comments have convinced me. Thanks everyone! By the way, what type of insulation did you use? Does it matter if it has the paper on it? I noticed that my local lowes only sells rolls of r13 with the paper backing.
  12. BS

    BS New Member

    Messages:
    50
    Location:
    Central Ohio
    In my attic were many large remnants of vinyl-backed wraps of hot water heater insulation just waiting for me to find a good use for them. It took 20 years (! :D ) but the new bathtub presented the perfect opportunity. I simply peeled the vinyl backing off and stuffed the 1" thick fiberglas around the tub between the open studs. To insulate the front I had to poke a hole in the drywall at one end and use a stick to push the insulation into the void, making sure to get it into the top of that space. By tapping on the tub wall I was able to locate spots that I had missed.

    I definitely compressed the insulation but didn't overstuff it, nor did I leave it light and fluffy as if insulating solely for heat retention. I was going mainly for sound reduction so I knew it had to be somewhat dense.

    A DIY book I looked at recently showed a roll of insulation tied around a tub before it was set in place. I guess that would work for heat retention but I don't think it would be dense enough to help much with sound because there would still be air space.

    If I hadn't been lucky enough to have the remnants, I would have used a roll of unfaced insulation. I bought a roll at Lowe's or HD a couple years ago, so you might have to ask for it if you don't see it. Also, fiberglas is fiberglas and it's simply the thickness of the batt that determines R-value.

    Wishing you quiet showering . . .
    - Bernie
  13. ekins

    ekins New Member

    Messages:
    1
    Location:
    Portland, OR
    I'm getting ready to install a tub and have the same question. What about spraying the tub with expanding foam insulation? It seems that would provide insulation and possibly also help make it feel more solid. I was thinking of coating the sides and back of the tub, leaving the front mostly open for plumbing and the buttom open to set in a mortar bed.
  14. Peanut9199

    Peanut9199 Customer Service Manager Plumbing Wholesale

    Messages:
    875
    Location:
    Ontario, Canada
    Look at post #4 from geniescience

  15. Top Dogs

    Top Dogs New Member

    Messages:
    3
    Location:
    Palm Beach County, Fl
    Whirlpool tub

    Can I insulate a whirlpool tub?
  16. Terry

    Terry Administrator Staff Member

    Messages:
    14,808
    Location:
    Bothell, Washington
    Sure, why not?
  17. Top Dogs

    Top Dogs New Member

    Messages:
    3
    Location:
    Palm Beach County, Fl
    Just wondering if the heat from the motor might burn out the motor if the air can't circulate in the confined space around the tub.
  18. ansman

    ansman General Contractor Remodeling

    Messages:
    1
    Location:
    Florida
    Re: insulating whirlpool tub

    I am in the process of installing a whirlpool tub in my own master bath. I was all ready to fill the cavity with fiberglass insulation, but I reconsidered for several reasons: 1.) the dust from the fiberglass could easily be drawn into the air passages of the whirlpool motor causing it to jam or overheat. 2.) the lack of airflow would contribute to overheating as well. 3.) even the stud wall insulation could leak dust and clog the motor.

    As a result, I am going to use spray foam (Great stuff) to insulate the wall cavities. I am also applying a 2-3" layer to the tub body to help retain the heat in all that moving water. Since the pipes hug the tub, they will be insulated as well. I am going to protect the area around the motor and maintain air flow around the entire tub. I am considering adding a vent to the cavity, but I haven't yet figured out where I would put it ( outside wall, closet, ?)
  19. johnfrwhipple

    johnfrwhipple I love these ACO Shower Drains - Best in Class

    Messages:
    3,828
    Location:
    North Vancouver, BC
    Spray Foam Warning for Tubs

    Careful when using spray foam (expanding) when insulating your tub. What many people don't know is that a can or two under your tub can lift the whole tub off grade.

    I have heard this story many times over the years and lucky for me a master plumber had all ready lived this mistake and taught me his lesson.

    The big rule is to fill that tub with water. Full. maybe two cans under the tub and nowhere close to the front edge. Just for extra insurance stack the tile boxes against the face of the tub in case the foam shoots toward that front edge.

    Leave that water in the tub for 2-3 days.

    You can then pack the voids with Batt Insulation.

    Good Luck
  20. wolfgangsnoopy

    wolfgangsnoopy New Member

    Messages:
    1
    Location:
    Sylvania Ohio
    I use spray foam - closed cell. Spray it in before you set the tub. Not only is it a 100% vapor barrier it has an r value of 7 per inch and it helps with sound. In addition to all of that - it is mold proof and will not break down over time. You can get a spray gun for about $50.00 and buy a case of great stuff. Or you can call a spay foam company to do you crawl or basement and hit the bottoms of the tubs / shower / tubs while they are out.

    Let me know if you have any questions.

    Marc
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