2 Bathtubs in 2 years

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Enak85

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Hi,

Just like the title says... we have gone through 2 acrylic tubs in 2 years. Both have developed hairline cracks in the bottom of them within a year of installation. The first was installed by a professional plumbing company and they placed the tub in Durabond 90 compound. The second was installed by the company we bought the tub from and they placed the tub in a sand mortar mix as well.

We have had the second company come back to inspect the cracking and they are claiming that the floor joists are not strong enough and are flexing when stepping in and out of the tub causing the cracking. The joists are 2x8 on 8ft span. Could that really be the problem?

Of course neither company would ever admit to an incorrect installation.

I would love to hear any other ideas you guys may have.

Bathroom Before.jpg

Bathroom During 1.jpg

Bathroom After 2.jpg

DSC_0497.jpg
 
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How thick is the subfloor?
Reason I ask is lot's of older homes used just 1/2" which is not enough.
 
Thanks for the quick reply. The subfloor is 1/2" plywood. The home was built in the early 70's.

Do you think that thickening the subfloor will help stiffen it enough? The installer is recommending to rip out my living room ceiling below the tub and sistering the joists.
 
Don't know who makes the ones we see up here that the builders use but the bottoms are reinforced with plywood like the one in this video. they are installed with out anything under them.
[ame]https://www.youtube.com/watch?v=5dXMGDRWpqg[/ame].
 
Acrylic is the material they vacuum form that is the shiny interior. Same way they make hot tubs now. That thin shell has no strength but is a form that they can spray chopped fiberglass over to give it strength. In hot tubs there is a big difference between brands how much glass the use and how strong the tub ends up being. You didn’t mention who made the ones you have had trouble with and as Neal pointed out there are other ways they can add strength in. Coming from an age of iron tubs the first time I saw someone putting big glob of mortar under a tub I asked what the heck are you doing. It was explained they are so weak you have to do that. I would say if you had the same brand twice do some research into other brands and find a stronger built tub. If there is room to add a thicker layer to the sub floor that wouldn’t hurt also. I would think 2x8 16 OC 8’ long should be ok. Just my guess.
 
We always built the skirt around soaker tubs and tile guys could make sure they were straight when they tiled around them. We had one where the plumber wanted to set it in mortar and the tile guy said, don't trust the plumber.
So we screwed blocks down so the tub would only fit in one place, tile guy was happy and plumber agreed "that" will work. Tile guy called us back, the tub was installed 1/2" out of square, the plumber said, well I had to remove the blocks to wiggle the tub into the mortar.:mad:
 
NEVER. NEVER EVER, NEVER EVER EVER

set a fiberglass/acrylic shower/tub with out a mortar bed

I dont care what you tube or uncle louie says.

it is common since, fiber glass will move up and down and eventually crack
not to mention the drain leaking. because it is stationary but the shower floor moves up and down.

I have been setting tubs and showers for over 30 years.

I know just a little bit about it


on some of the plywood reinforced tubs, you STILL have to add mud.

all depends. you FIRST set the tub in the hole and LOOK under it.

is it sitting on the floor 100% ? have you built a tub surround/steps for the tile

and raised the tub to accomadate the tile/surround ?

if it is not 100% supported, grout it.

NOT EXPANDING FOAM, that **** breaks down with time, mice make nest. etc etc


if you step in the tub, it moves ANY AT ALL grout it!!!!!
when you get thru, a 10 year old kid should be able to jump up and down, laugh, squeel, and beat his sister up with out the bottom moving
 
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here is the deal on the reinforced tubs. yes, they are reinforced

yes they have wood under them.

but, the bottom of the wood is NOT in sync with the lip of the tub.

so, when you install the ledger board to level the tub.

you raise the tub to do so. and leave a 1/2'' or whatever gap under the tub.

the tubs are not leveled then the wood attached at the factory.

wood is slapped on as they spray..they do not deal in close tolerance

column.jpg
 
I didn't mean to say, I wouldn't use mortar, just that all tubs are not equal.


i got you, not argueing, just throwing out their my experiences

they get cheaper and cheaper each year
 
I have seen some strange things. In a reno a few years ago we took one out it had mortar under it but there was still a gap. I think they fill the tub with water while the mortar was wet. There was a crack in the fiberglass on the bottom and when you stood it up to the light you could see light thru the weak area. They put it back in.:rofl:
 
I got 500 gallons of water in my acrylic and fiberglass hot tub and don’t have any grout under it. I know its different but also the same in how they are made. No reason a tub can’t be made to support itself except they don’t want to. I have no idea if anyone makes one good enough.
 
I got 500 gallons of water in my acrylic and fiberglass hot tub and don’t have any grout under it. I know its different but also the same in how they are made. No reason a tub can’t be made to support itself except they don’t want to. I have no idea if anyone makes one good enough.

Your tub has foam under it.
Most of the builders here use the same locally made tubs and they seem to get away without mortar. I haven't heard of any cracks but I have heard of plumbing leaks like Frodo mentioned. I bought mine thru the plumber doing the house next door so it could be delivered with his order and he said no need but I mortared mine anyway.
 
Thanks for all the responses and suggestions guys.

I originally thought that there could have been a gap between the mortar and the bottom of the tub but both installers claimed they filled the tub with water to set the tub in the mortar bed.

Perhaps the mortar mix was too wet and flattened out too much before it hardened. The only way I can think of to check that is to remove the tub. The tub has to be replaced anyway because of the cracking so we will see once the tub is removed if there was a gap under the tub.

We are considering the following options at this point.

1. Bath Fitter Insert
2. Double up the subfloor and replace tub with same or different tub model
3. New drop in style tub
4. Steel/Porcelain Tub
 
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Thanks for all the responses and suggestions guys.

I originally thought that there could have been a gap between the mortar and the bottom of the tub but both installers claimed they filled the tub with water to set the tub in the mortar bed.

Perhaps the mortar mix was too wet and flattened out too much before it hardened. The only way I can think of to check that is to remove the tub. The tub has to be replaced anyway because of the cracking so we will see once the tub is removed if there was a gap under the tub.

We are considering the following options at this point.

1. Bath Fitter Insert
2. Double up the subfloor and replace tub with same or different tub model
3. New deck mounted tub

My thinking is you are trying to stop it from moving with mortar so weighing the tub down is kinda giving it clearance to move up and down.
So when you pull the plug the tub goes back up and you have a gap.
I think it should be pushed down only so it sits on the back 2x4 and the floor in the front.
When I did mine we fit the tub and attached another 2x4 above the flange so when we put it in we knew it was down on the back 2x4 and weighted down the front till it sat on the floor.

The MISTAKE we did make is we put that 2x4 in the back level and we should have checked the tile edge for level, we ended up with a half in difference from one end to the other, who knew?
 
the problem a lot of rookies have is just dumping crete on the floor then setting the tub.

the mix will squish out from under the tub. you must use a small form to hold the crete in place

you also use tar paper on a wood floor,


thats how i do it, i dont have problems, so i think its the right way



my personal opinion, i would not use a fiberglass tub in my house.

cast iron or cultured marble only
 
Thanks for all the responses and suggestions guys.

I originally thought that there could have been a gap between the mortar and the bottom of the tub but both installers claimed they filled the tub with water to set the tub in the mortar bed.

Perhaps the mortar mix was too wet and flattened out too much before it hardened. The only way I can think of to check that is to remove the tub. The tub has to be replaced anyway because of the cracking so we will see once the tub is removed if there was a gap under the tub.

We are considering the following options at this point.

1. Bath Fitter Insert
2. Double up the subfloor and replace tub with same or different tub model
3. New drop in style tub
4. Steel/Porcelain Tub


#4. steel tub :2cents:
 

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