# creaking bathtub - Spray foam?



## wnabcptrNH

the spray foam in a can is not closed cell insulation and is soft when it cures. spraying it under there may or may NOT help.


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## Thurman

One of my favorite repairs with fiberglass tub/shower sets. Is this unit fiberglass also? Can you access the bottom of the unit from any wall? I have done these by removing a baseboard, then cutting the sheet rock up within 1/2" of the top of the baseboard, and removing this piece of sheet rock. If you can see the bottom of the tub/jacuzzi then you can do this: I use a wooden yard stick to place a heavy-duty garbage bag under the unit. Then I have a can of Great Foam (low expanding) with about a 36" length of tubing on the nozzle, and the end of the tubing taped to a stick of some type. Using the stick, I place the end of the tubing into the garbage bag, then start squirting the GF into the bag and moving the stick/tubing around. When this swells it will add support to the bottom of the unit. I also fill the tub/jacuzzi about 1/2 full for this. It's a tedious process but has worked well for me. David


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## Jim F

Where do you buy 36" tubing for the spray foam?


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## gaffshot

Thurman said:


> One of my favorite repairs with fiberglass tub/shower sets. Is this unit fiberglass also? Can you access the bottom of the unit from any wall? I have done these by removing a baseboard, then cutting the sheet rock up within 1/2" of the top of the baseboard, and removing this piece of sheet rock. If you can see the bottom of the tub/jacuzzi then you can do this: I use a wooden yard stick to place a heavy-duty garbage bag under the unit. Then I have a can of Great Foam (low expanding) with about a 36" length of tubing on the nozzle, and the end of the tubing taped to a stick of some type. Using the stick, I place the end of the tubing into the garbage bag, then start squirting the GF into the bag and moving the stick/tubing around. When this swells it will add support to the bottom of the unit. I also fill the tub/jacuzzi about 1/2 full for this. It's a tedious process but has worked well for me. David


Yes, it's fiberglass and i have complete and easy access to the underside of the tub b/c it is a jacuzzi tub with removable side plate. So you are using the gap filler designed to not bow window and door frames (low expand)? Why the garbage bag trick? What does that do? :thumbsup:


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## COLDIRON

I used spray foam under a shower a couple years ago, I just sprayed it all around under the fiberglass pan(it was open under where the drain is) when it expanded it just came out under where the drain is. I do not recall what can it was but it was great stuff. The best thing could have ever done under there, no more creeks and solid as a rock, it was getting ready to crack the fiberglass when I did it.


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## the_man

a customer of mine last year was having this happen with an ADA shower pan, it eventually cracked the base. rather than pay me a huge amount of money, he called in someone who drilled a bunch of holes in the base, sprayed a small amount of foam into each hole, then fixed the gelcoat so you couldn't see after he got done. looked great and was very solid. my only concern with doing it from the side is over expansion causing cracks or waves in the 'glass. i'd go slow, and do a couple passes (don't try to fill it all at once). Good luck, let us know how it works


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## gaffshot

Should the plumber guy who i paid to install the tub 4 years ago have put something down there when it was installed? Are there rules or generally accepted installation practices for things like this? Did this guy do it wrong from the get-go? Seems like if there's nothing under the fiberglass to support the weigh of a person (or tub full of water) then of course it will eventually flex and crack, right? 

Wonder if Holmes on Homes would rip my whole bathroom out to fix the problem? :thumbup:


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## the_man

I'm pretty sure he only "makes it right" for canadians, so probably not :laughing: I generally put mortar under every tub i install, to give it a level base. There was a thread on it a couple days ago if you want to go looking for it


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## Michael Thomas

FWIW, some manufacturers now allow minimally expanding structural foam as a support, for example Jacuzzi specifies support by "The use of materials that provide a level installation are allowed provided the method used will insure a level bath that is supported from the bottom. Materials that may be used are a floor leveling compound, mortar, plaster or minimal expansion structural foam having a density of a minimum of 5 lbs./cubic feet".

I have discussed the use of "Great Stuff" when used as a tub or shower floor support with Dow Technical support, and their response is a definite "Not Recommend" as: 1) the density (2.2 lbs/cu/ft for the standard product and 1.3lbs/cu/ft for the "Pro" product) is too low, 2) no "GreatStuff" product can be guaranteed to cure properly when used in this type of "spread-out" application, and 3) that such products are not intended for structural use (for example, they may not expand back to original cured volume after repeated compressions).

The bottom line is that that the use of such products as support or re-suport tub and shower floors is approve by neither the plumbing fixture manufacturers nor by Dow Chemical. Such foams are not "structural" products, and even if such repairs are initially successful they may not be durable.

As for alternative materials, far as I have been able to determine there is no site applied 1 part (non-mixed) structural foam product available for this use.

So while I'm not saying it won't work, if the tub is not supported "per manufacturer's installation instructions" might find yourself in this situation.


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## wnabcptrNH

the_man said:


> I'm pretty sure he only "makes it right" for canadians, so probably not :laughing: I generally put mortar under every tub i install, to give it a level base. There was a thread on it a couple days ago if you want to go looking for it


Not true he did a house in California as well.


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## Homerepairguy

Michael Thomas said:


> Materials that may be used are a floor leveling compound, mortar, plaster or minimal expansion structural foam having a density of a minimum of 5 lbs./cubic feet".


Plaster sounds like an ideal material to use for tubs that are already installed. One could build a rectangular frame out of 2x2 inch lumber, line it with a plastic sheet, then just pour a flowable plaster mix in it.

My questions in doing this are:
1. Would the plaster shrink to defeat it's support function?

2. If the plaster surrounds the drain pipe, would it cause major problems later? Seems that plaster would be easy to chip away using a cold chisel if necessary. 

Any comments on this?
HRG


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## Thurman

I did not, nor do I, advocate using any "Great Foam" type product to build up for a new shower/tub/jacuzzi install. I have used a mortar made specifically for this on new installations. The tubing I was referring to was just some clear, flexible, plastic tubing which can be cut to spec at most big box stores, it will just fit onto the nozzle of the GF can. The garbage bag trick is to keep the foam from sticking to the floor and/or the bottom of the tub/shower/jacuzzi. I have had to pull one, only one, out after an application of GF. It sticks well. The procedure I was referring to is to "repair" a bad situation, to say the least. As stated: A new installation should not be done with GF, only use a mortar base designed for this application. I have heard of others using "plaster of Paris" on these also. David


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## Jim F

OK so the tubing is just close enough in diameter to fit over the can tube then I guess it could be sealed with electrical tape so it doesn't leak out around.

The trouble with these fiberglass and acrylic tubs as far as I can tell is that very few of them recommend thin set under the tub during installation and that is the best solution. Unfortunately, if you use the thin set and still have a failure, you have voided the manufacturer's warranty. Of course they only warranty the replacement of the tub, not the installation so you are are in a sort of no-win situation.


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## JCwel

I have a similar shower pan issue with an already installed shower.. I have a Vikrell shower pan (36 x 36) that has structural cross ribs underneath. There is some flex and it has the popping, snapping, creaking sounds. The shower pan sits on a wood floor which has a sheet of tar paper on it (to eliminate creaking sounds :no. I have access to the back of the shower pan but only enough space to get a thin (1/4"OD 3/16" ID) vinyl tube under to push foam or anything else I may be able to get thru it. My question is: there are other foam products out there now for use outdoors for fish ponds, waterfalls, etc. It is typically black in color, low expanding, and I believe it has a higher density than the typical indoor insulating spray foams. Has anyone tried using this under a shower pan? I'm thinking this may not be as apt to compress. Any thoughts would be appreciated. Thanks.


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## Lightfoot

gaffshot said:


> Why the garbage bag trick? What does that do? :thumbsup:


I would imagine the foam inside expands the bag in the shape of the tub so as not to adhere to the floor or your tub. Just a guess on my part.


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