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Discussion Starter · #1 ·
I have a shower with a fiberglass pan and ceramic tile surround. The pan is very springy since I assume there is nothing underneath it. I am afraid of two things: The pan may crack, and or the drain assembly may break.

Has anyone ever fixed this problem from underneath? Like cutting a hole in the ceiling below and injecting an expanding foam?
 

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Foam is about the only thing I can think of is there is no access. But be careful with expanding foam, especially is you can't see what it is doing. It will expand until it uses up its chemicals, regardless of what is in the way. It can push out walls or raise the shower pan. Maybe you could use the minimal expanding foam. Might require another application, but safer.
 

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The problem with expanding foam is that it contains air space. Once it gets compressed, it stays there. While I admit that a smaller flex is better than a lot of flex, it is still not the total answer. If you can cut a hole from below, I would try doing so from one side and packing some very dry (just moistened) mortar mix under the pan. A mortarbed should have been installed originally. If you use the foam, get the minimal expabsion type. You do not want to create a bow in the pan.
 

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Discussion Starter · #4 ·
Thanks very much guys! Since I really can't see what is going on under the pan, I think the cement mixture is the answer. I sure don't want to make the problem worse! Problem is I don't know what kind of sub floor was installed until I remove the ceiling.
Thanks again for some sound advice.
 

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Foam

Hi CC I had the same problem about a year or two ago, I had plenty of room under the pan where the drain line went down I shot a can of foam in there and WA la problem fixed.

No more flex. Note as long as you have an opening for it to expand to it will not hurt anything the problems happen when it has no where to go.

Good luck

EDIT: My shower was over top of Oriential strandboard if that helps.
 

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Finally, someone else HAS the problem I HAD. My fiberglass tub/shower enclosure had that spongy floor feeling since day one in this house, the house was two years old and they did not use this bath. I had access to the bottom of the tub floor from two separate wall, one a bedroom wall, the other the wall between the bath/toilet and the room with the sinks and mirror. I removed the baseboards within each room, then cut a section of drywall about 1/2" less in height than the baseboard out, say about two feet long, so I could re-use it. I found that the tub floor was not sitting on anything as it should have been. I placed heavy duty contractors garbage bags underneath the tub floor perpendicular to the length of the tub, with the opening to the back wall of the tub, the bedroom side. Then I got me a piece of clear tubing that would just slip onto the plastic nozzle of that "Great Foam" stuff, about three feet long. I placed one end of the tubing into a garbage bag and blew the Great Foam into it as I pulled the can back slowly. It worked, the foam spread out until it reached the floor of the tub then spread sideways. I wasn't trying to fill the entire void, just enough to add strength. I did, I think :whistling2:, four of the bags like this and when they had finished spreading and solidified, I had the support I needed. The it was just a little drywall repair, replace the baseboard and things have been fine ever since. Good Luck, David
 

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Discussion Starter · #7 ·
Thanks all for the replies. Well, I used the expanding foam and it worked very well. Only problem is I think the sides are resting on wood and now it squeaks! lol Can't win for losing.
 

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Guys, did you use the Great Stuff Gaps & Cracks foam (red can) or the Great Stuff Window and Door foam (blue can)? Apparently the Gaps & Cracks is rigid foam while the Window and Door foam stays flexible...
 

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Guys, did you use the Great Stuff Gaps & Cracks foam (red can) or the Great Stuff Window and Door foam (blue can)? Apparently the Gaps & Cracks is rigid foam while the Window and Door foam stays flexible...
The Gaps & Cracks would expand too much and likely bow or crack the base, it's pretty strong stuff. The Door & Window is the right stuff.
 
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