I don't know how else to explain it. This is new construction and we have had a tremendous amount of trouble with our builder.

It does not feel like this everywhere on the bottom but it does feel this way towards the center of the tub. This does not seem normal to me. Please let me know your thoughts.

sorry to add to your list of woes with your builder. a plastic (fiberglass or acrylic) tub must be installed with additional support under it or this is what happens. you will need to get access to under the tub and squirt some expanding foam, trowel in some mortar or structolite or at very least push in some shim shingles to remedy this improper installation.

If it's a non-metal bathtub and it wasn't set on Structolite, mortar mix or whatever the manufacturer
suggests, unfortunaltely you may experience movement which will lead to problems, (cracking/splitting).

e-plumber
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John William Gardner 10/8/1912 - 2/16/2002

Repair your leaking Plumbing fixtures ASAP [www.theplumber.com]
This slow drip will waste 7+ gallons of water per day.

My boss doesnt like concrete or anything under our tubs because he says it can squeak.

I have been with him for 5 years and have never put anything under the tub and never had 1 complaint.

Lasco and sterling both say you dont need anything under them.

I dont know about National, kohler, or Aker.

Kohler tub/shower modules have always been absolutely horrible quality.

Aker(what I install) is having problems the past 6 months. They were bought out by Maax and are now 1/3 lighter. I recently gave up complaining about how thin the walls are. We have sent back 1 whirlpool tub which was cracking under my feet.

what brand is the tub and is it a whirlpool or tub/sho combo?

National is usually the best quality in my opinion. Also alittle more expensive. I like lasco for the lower end.

I'm assuming you have a fiberglass tub/shower unit. The "squishy" feeling you describe is the tub bottom flexing.

Before setting a fiberglass tub, a good plumber will take the time to place mortar or plaster of paris underneath the tub to give the bottom some support.

Chances are, this wasn't done in your case, as many (but not all) new construction plumbers are mainly concerned with speed and won't take the time to do something like mix up some mortar or plaster to put underneath a tub. Instead, it's "set it and forget it."

If the tub is on the first floor and you have access from the basement, you may be able to shove some mortar underneath the tub through the hole in the subfloor that was cut out for the tub drain.

If the tub is on a second floor, then there's no access (unless there is a closet next to or behind the tub and you are willing to cut open a closet wall).

Even with this type of access, it's going to be difficult to push enough mortar deep enough under the tub. Some people on this forum have suggested using expanding spray foam, but you have to be very careful not to shoot too much foam, as it could over-expand and possibly damage the tub. (Personally, I'd go for the mortar.)

This is a perfect example of how it's much easier to do something the right way the first time (when the tub was orginally installed), than attempt to correct a problem after the fact.

Good luck, let us know how you make out.

-Ken

Wisconsin plumber,

I agree it's tough to find a well-made fiberglass tub/shower unit.

I've never heard of National brand, apparently, it's not common in my area.

I've never installed Kohler (I figured they would be good quality, however).

I've seen a Maax unit where the gel coating was wearing away on the non-skid bumps on the bottom of the tub in a house less than 3 years old.

I don't like Aquaglass - their designs are ugly, in my opinion, and I don't like the spongy feel of their fiberglass.

The brand I've most installed is Lasco. I like their looks/styling, and their prices are fairly reasonably. However, I think their quality has dropped dramatically in recent years. One plumber I know complained of thin spots in the fiberglass. On a recent remodel I did, I had a heck of a time finding a three-piece Lasco tub shower unit that didn't have a substantial defect (many had poorly formed drain openings, I inspected at least six units). And the unit I eventually selected had a thin spot that I didn't discover until the tub was set and the bathroom drywalled (I was in a closet behind the tub and saw the thin spot, which was revealed by a halogen worklight in the bathroom).

-Ken

the big orange box stores sell lasco around here.

Go with the mortar trick. I'm not a fan of expanding foam for anything other than sealing wall penatrations like crawlspace wallsl or basements.

I got smart one day and decided I would insulate behind some drywall with it around a skylight/roof window in my old house. I drilled two holes. One on each side and squirted in the foam. Foam oozed out of the holes for hours making a total mess of the walls around it. Then to make things worse, it pushed the drywall away from the wall!

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a while back, i had a call for a leaking shower drain. it was one of those compression drains. the shower base had nothing under it. i repaired the leak and thru the opening in the plywood was able to stick the extension from the can all around and spray some foam. so, while mortar or strutolite may be preferable, spray foam as an afterthought works better. IMHO..

Yea, Its definitly cheaper than tearing out and resetting it.

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I installed a Gibralter enamel coated steel tub last year. I emailed Eljer as to if mortor or stocolite was needed underneath, they said, no.

Would any of you folks layed some down anyway??

Possibly if requested by the owner only, to take that hollow sound of steel bathtub away.

e-plumber
-----------------------------------------------------------------------------------------------------------------------------------

"The society which scorns excellence in Plumbing as a humble activity and tolerates shoddiness in philosophy because it is an
exalted activity will have neither good Plumbing nor good philosophy: neither its pipes nor its theories will hold water." -
John William Gardner 10/8/1912 - 2/16/2002

Repair your leaking Plumbing fixtures ASAP [www.theplumber.com]
This slow drip will waste 7+ gallons of water per day.

americast tubs are steel and they don't recommend anything under them either.
i should know why but i don't.

just curious - exactly how much plaster/structolite do you put down? on a tub, you're only trying to fill the void between the skid legs on the frame, correct? or is the trick to lay it down under the whole frame, so the whole thing is sitting in the mud?

Packy,
Our company had been putting Gypsum under the Americast tubs for years, then one time (about 2 yrs ago) the steel popped loose from the "cast" on the floor of the tub (after the tub had been in use for a few weeks) it would act like the center of the game "trouble" when it was stepped on, so we had to replace it free of charge. AS refunded the cost of the tub replacement and said they had a problem with the adhesive that holds the steel to the plastic and said they corrected it. It happened again a few tubs later and again AS refunded the cost of the entire replacement process, but said that would be the last time and to NOT put anything under the tub anymore.
None of the tubs that I had installed (at least 50 of 'em) with Gypsum ever had a problem. In fact the Americast Tub in my home is set in Structolite Gypsum and is perfectly fine. I attribute the problem to poor workmanship (stringer, skirt support etc.) and/or mixing the Gypsum too dry. But I'm not allowed to set them in Gypsum anymore for liability reasons. Especially since AS started disallowing it in their paperwork. It's a shame because I think the end result is far superior when set in the Gypsum.

I'd say its a damned if ya do, damned if ya don't situation there. Okay on one way they say it caused a failure but the other way the drain bounces around and that causes a leak. So what to do... Pick out a different tub? seems logical to me.

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We're having this issue with the fiberglass tub/surround my nephew installed for us. When I step in the tub it creaks and I see the caulk give. What to do? I can't see taking up the beautiful new floor tile and we're out of money!! The only access we have to the tub underside is temporary - only until we finish the ceiling repair in the kitchen below. He did tell me he poured in one 60lbs bag of sand under it - this hardly seems like enough. I've been reading the advice of plumbers for hours tonight and it seems like spray foam is NOT the best but I wonder how we can put mortar or something else in from below. Looking up through the current 1 foot deep hole (hole through dropped ceiling and original wainscoat ceiling) I can see the end wall (drain end) of the tub and a 1/4 inch or so of sand resting on a subfloor. Any ideas how we can get mortar up there? There is already the bag of sand filling the small space between the tub and sub floor and I can only see the very end. With the plumbing, ceiling joists and floor joists crossing there isn't much room to get at the space. It seems like whatever the substance we use it would have to be in liquid form to be able to fill the full space under the tub. I have put a call in to a plumber but I want to be prepared in case he has not encountered this before. Thanks for reading a post from someone stupid enough to have a non plumber do plumbing!