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Does anyone know of any advantages or disadvantages to filling the cavity under an acrylic bathtub with expanding foam ? The plumbers I’ve used on past jobs have always set the tubs in non-shrink grout with good (solid) results. A new guy I’m using swears it’s better to spray foam in after the tub is connected. Any advice one way or the other is much appreciated. Obviously, this is something that would be difficult to fix later !
Thanks,
Scott
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Replies
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do not, absolutely DO NOT go with the foam. throw the bum out! the failures are spectacular! want me to be specific? with both hands and a boot!!!
brian
*Brian, any specifics on those failures ? Scott
*The product that I have used is called Gypsalite. It is like a lite weight concrete. When you light the bag it's like air. It is specifically designed for mud-bed type applications. It holds its form like whipped cream until you smush the tub into it. After it hardens, it's as though the tub and floor were connected.
*The product that I have used is called Gypsalite. It is like a lite weight concrete. When you light the bag it's like air. It is specifically designed for mud-bed type applications. It holds its form like whipped cream until you smush the tub into it. After it hardens, it's as though the tub and floor were connected. Any Plumbing, Drywall or Commercial Supply house should carry it. Let me know if you use it and how you like it.
*sure. i've been servicing the plumbing on a particular apartment complex (circa 1975) in the san diego area for 6 months now. EVERY tub shows stress cracks at the corners. some tubs have shown full 1' diameter holes exposed - probably where repairs where made.my intuition tells me that after repeated filling of tubs or simply weight of occupant or both eventually crushes the foam a mm at a time until the weight of the tub is carried by the corners, creating stress cracking at these areas...and boy is it fun if the foam was allowed to spread and envelope a leaking tub drain...you can always run a search here for "brian" "smith" "foam"brian
*Hi S.D.,You got your answers and they are 100% right. Use Gypsalite...works like a charm...don't use expanding foam...asking for trouble.If this new guy doesn't know how to install any other way than with expanding foam...then ask where he learned his trade. Throw him out and report trade school's name to local plumber's union.Your guy doesn't know his stuff.Davo
*Brian, thanks for the great advice. My first instinct when the plumber suggested foam was that this wasn't the right product for this application. The concern I had was that the floor of the tub between the support rails always seems weak and feels "spongy" under foot. The non-shrink grout always solved that and I haven't had any complaints yet. After reading your last post, I suspect that the foam would eventually feel spongy too.Dustin, I haven't heard of Gypsalite but will definitely look into it. If I find it here (Vancouver) and decide to try it, I'll let you know how it goes. Thanks, Scott
*The acrylic tubs and showers I use most often are Sterling, by Kohler. These units have support ribs built into the bottom of the tub/shower, and the unit sits very flat on the floor. Kohler says they void any warranty if expanding foam is used to set these tub/shower units. They said we could use a cementious type product if we wanted, but they did not recommend it, nor did they feel it would be necessary.I have gotten into them when done, and they feel very solid underfoot. James DuHamel
*Simply have him follow the tub manufacturer's installation instructions. No instructions? Call their tech line and ask.Easy to do. The tub manufacturer doesn't want a failure, and neither do you.
*Scott,We've used good old plaster of paris - gotta move quickly though as it sets in 10 minutes or less - often less, and sometimes much less depending on temperature. The Gypsalite sounds interesting. How long does it take to set up?Cliff.
*A guy I know had a simular situation where his contractor wanted to use foam. I advised him to do what Mongo said and contact the tubs manufacturers tech rep. Therep gave him reconmmended installation instructions which he turned over to the contractor who then used the concrete.