[CharlieR]

Hey all,

Question. For a acrylic/fiber glass bath tub, not sure what exactly it is, how recommended is the mortar underneath for support? It has 4 feet, but I'm more concerned about the rest of the area where there isn't feet. It is a Kohler Archer tub if that is any help. I really want to do it, but a plumber has told me not to bother, should I see if he'll do it anyhow?

THanks in advance for any advice.

Charlie

 

[Alan]

While the base may be strong enough to support the weight of the tub, we usually put mortar around where the legs sit, to prevent the tub from shifting horizontally after installation.

If it's your tub, and you want mortar under it, he should do it.

 

[jaydevries]

unless it is full contact bottom and sits level . i always set in piles or full bed set of mortar or speed set just due to the amount of units i have seen crack due to not enough support or over weight persons

 

[joecaption]

What's the directions say? Go online and check. If it says morter there's a reason for it.

 

[funfool]

When the plumber says do not bother with it, that skeers me and want to know more about the plumber. :huh:

For the couple of dollars and few minutes it takes, I would.
And once the tub is sitting in the wet mortar, I fill the tub with water for the weight.
This means dragging a hose through a window somewhere, or fetch it with 5 gallon buckets if needed.

But yeah, if I set that tub, is getting mortar and then filled with water while the mortar cures.

 

[CraftsmanConnec]

Craftsman Connection - Do it right.

I'm a kitchen and bath remodeling contractor for nearly 15 years. I've been a former building inspector and home inspector. Licensed General contractor in California and Texas, Angie's List Super Service Award winner in 2010, 2011, 2012.

The reason for the mortar bed is two fold:First the feet (aka shipping blocks) are not going to make the tub sit level, so the mortar also may be needed under the feet. Sometimes you won't see feet, there will just be a piece of OSB plywood.
Secondly, the vinyl/fiberglass will dry out and crack over time if it it stressed without support. I've seen hairline cracks in these types of tubs that are 10-20 years old. I don't think I remember seeing a mortar bed in all the tubs I've pulled out. Just because some builder or plumber is being or was lazy, doesn't mean that you should be. The mortar bed isn't easy for a beginner, but start by putting blocks under it to prop it up to get it level so you have an idea of how much mortar you will need. Don't make the mortar too wet or it will sag away from the tub as your setting it.

 

[jaydevries]

i do not recommend filling tub with water after setting in mortar bed due to the weight of the water will flex the tub pushing mortar down. which when water is drained will flex up causing a slight gap which causes a flex point in tub.
i am sorry to disagree with another post but this is what i have seen.
also if it is a full contact bottom ridgidized foam tub i use about 2 tubes of silicone underneath to prevent squeaking

 

[funfool]

Is why we have forums and discussions.
How much do we think that new tub deflects when adding water?
I think a brand new tub is not much, adding mortar under it and filling it with water, is only going to apply pressure in the same way applying pressure to wood glue allows it to have a stronger bond.

water is not required, I do not see a reason to quit adding it any time soon.

 

[Alan]

The other reason for not adding water when setting a tub :


Typically we build our decks taller than the tub itself. This means using something to take up the space. It's never going to be just perfect.

Get it within an inch, and then float the tub in a bed of mortar.

Use shims or chunks of 1/8 plywood between the tub and the deck. This helps keep a uniform gap for caulking.


Now the reasoning : If you fill the tub with water, it will pull all the tub weight down from the rim of the tub. NOT the strongest part of the tub and it can crack.

If you let the mortar set up, then you can pull the shims, and the tub will always maintain the 1/8" gap and then you caulk the tub to the deck.

For alcove installations it's still a good idea, but usually alcove tubs have better support under them. If it was my own, i'd do it.

 

[747]

yes for stability

 

[CharlieR]

Thanks everyone. I had planned to do most of this myself, but I am way behind schedule! Finding out DIY with little kids is not easy!
Anyhow, appreciate all the feedback. I guess I can ask if he'll do it if I want and if not, get someone else, or someone to just do that part with me later or something.
THe instructions mention an either or, mortar, or gluing the feet.... seems a bit difference to me, but what do I know! :wink:

It is an alcove installation. Does the rim still need support? I need to double check the instructions, but for some reason, I don't recall it mentioning that. I know the tub I took out had it. Seems like a good idea regardless.

Do any of you put any plastic sheeting between the mortar and the tub? I've read that is not a bad idea in case you need to remove it later, that it's not stuck to the mortar, just supported by it....

 

[CharlieR]

So follow up question. Can you put in Mortar support, after the tub is already installed? Kind of push it under for some added support? Once the tub is level already?

 

[Alan]

So follow up question. Can you put in Mortar support, after the tub is already installed? Kind of push it under for some added support? Once the tub is level already?

Kinda depends on what the bottom of the tub looks like. Might be easy in some cases, but more difficult in others. I'm assuming you're asking because he refused to set it in mortar? :whistling2:

 

[CharlieR]

:whistling2:
Wouldn't say refused... lets just say strongly didn't think it was necessary and I'm unfortunately easily swayed / like to avoid confrontation and am behind schedule so the wife just wants things done :jester:

I can take a picture. Essentially there are 4 feet... integral skirt. However, I have access both from the foot of the tub, and slightly lesser access from the head of the tub... so I could scoop some in there and push it in... at least add some support in places other than the feet... provided the consistency of the mortar is such that this is a possible task?

 

[retired guy 60]

I agree with joecaption. Go online and see what the installation instructions call for with regard to your particular model tub. I came up with this from the Ask Me Help Desk:
"If the manufacture does not provide support ... then the installer must bed the tub himself.
If the tub isn't bedded with mortar, cement or Structolite then it will 'flex and give' a bit every time someone steps into it. In time this can rupture the drain seal and develop a leak. It can also put a strain of the fittings below the drain. And now you know the rest of the story."

 

[Ghostmaker]

According to the manufacture install instructions the tub must rest on it's feet. They do not say to use any concrete additives. Make sure it is sitting on the floor and not supported by your deck. Also make sure you DO NOT install your faucet through the tub itself.
Kohler fiberglass has always been a top brand tub with thick over all construction. Follow the manufacture install anything else may void your warranty.

 

[Alan]

sure you DO NOT install your faucet through the tub itself.

L O L ? :whistling2::whistling2:

 

[Ghostmaker]

L O L ? :whistling2::whistling2:

Really, I read the instructions and they specifically say not to drill through the upper lip of the deck tub. And install the faucet through the deck itself. So may I ask what is so funny?

 

[Alan]

To the OP : It looks like they give you two options for setting the tub.

For mortar bed installation, set
the basin area in 1" (25 mm) to 2"
(51 mm) of mortar cement.

For adhesive installation, apply a
generous amount of construction
adhesive to the bath feet.

He should have done one or the other. I would have strongly requested that he did. Since they are giving you the option for adhesive, it looks as if they don't think their tub needs the extra support, and the mortar is just to lock the feet in place.
Your two options at this point are to pull the tub and put down some adhesive where the feet are, or try to shove enough mortar under the tub to lock the legs in place. If there's no tile on the walls yet, i'd vote for option A. It really would be a lot simpler. Mark one of the feet, pull the tub... measure for the rest of the feet...squirt some construction adhesive where your marks are, and put the tub back. Furthermore, since you made the request, he talked you out of it, and now the tub is moving around, he should come back and do it, IMO.

 

[CharlieR]

So yes, the tub is shimmed/resting on its feet. However, from my own opinion, the feet... seem somewhat inadequate compared to had mortar been used, but... it's done. It is sitting on shims, and the shims are screwed in place (from when the tub was put in place), and essentially the shim/feet are surrounded with PL glue. so although it's not "glued down", it is glue surrounded and I figured just as good?

I mean, it feels generally fine standing in it, but ... Im an over-worrier

What do you guys use to protect the tub while working in and around it?

Somebody on another thread of mine suggested it's ok to stick the front legs of a ladder in the tub to reach up for higher work... should I stick something under it? Is that safe considering the tub is on it's feet and not mortared down?

Thanks for all the help everyone.