How to mortar a whirlpool tub?

[BSAKing]

I have a tub I am putting in - it needs to be supported by stringers on 3 sides (to level the tub only). Then it will need approx 1 1/4" of mortar or so underneath it to properly support the base.

I am thinking of using relatively soft cardboard triangles stapled to the floor to hold the mortar to get the tub on it. I only have access from the back and then only before I slide the tub in.

I am looking for clues as to how to go about this. I can't open up any adjoining walls (or rather am unwilling to), so to me it seems the mortar bed is crucial for proper support on this thing.... The issue will be to get the mortar at the right consistency so it will not run out, but yet can be 'squished' a bit once the tub is in.

They say NOT to fill the tub while doing this, which is a good thing since I have nothing hooked up to be able to do that.

I attached a few pics here of it so you can sort of get an idea of the issue....

Like I say - just looking for /clues/pointers/observations before I get into it...... (no rude comments puhleese! lol)

Thx, BSA

[BSAKing]

A corollary question regards the electrical. I currently have a 15 amp wall outlet with a GFI in it and a separate 10 gauge solid wire dragged back to the panel ground and will be tagged to the motor block.

Would I be better server by a GFI 15 amp installed in the panel? Or does it make any difference? The panel one is like $100 and the wall box mounted one I already have.

thanks

[Mikepier]

What does the manufacturer say? The installation manual should say how to accomplish this, but if I had to guess, just throw a mound of mortar on the floor, then lift up tub slightly while pushing it into place so it makes a good form when it sits on the mortar. Does the manual say you need mortar?

As far as the electrial, it does not make a difference to have a GFI outlet or breaker, but I think you need to run a new circuit anyway either way because 1) 15A is not code for a bathroom outlet and 2) a whirlpool bath might need a dedicated circuit.

[BSAKing]

It does not say anything at all about how to accomplish the mortar issue. It does say you need it. Looking at it, the actual tub 'target' area is much less than the overall base area, so perhaps a sizable mound of mortar is all I need to do....

I have already run a separate 15 amp circuit from the panel with a separate ground for the motor assembly directly from the panel. 15 amps is what that motor calls for. I did run 12 gauge wire though because the run is about 30 feet and it is a motor draw, but breakers and GFI's are 15 amp as called for.

[dadiOH]

Right consistency isn't hard. Just shovel it under as much as you can, push it back all the way with a 2x4 or whatever, shovel under more, push, etc. Pack it as solid as possible.

[Bob F]

I would imagine that unless care is used, it would be easy to lift the tub doing this.

I have a hand operated grout pump that I would imagine would work well for this. I used it for leveling a large concrete hottub by jacking up the low side and pumping grout underneath it.

[Mikepier]

If you ran 12 gauge, you should use a 20A breaker . Why not just put in a GFI breaker. It's not that much more than an outlet. How did you get $100?

[Oren]

I'm the odd man out. When my tub was installed I filled the tub and then used expanding foam under the tub. Five years later - no problem!

I let the foam cure a couple of days, before I drained the tub. It is solid, no flex in the bottom of the tub.

[Limp Arbor]

Doesn't the right side panel also come off?

Can you put the tub in place with the panels off then shovel it under through the access panels.

Where are you planning on putting the outlet for the motor?

It looks like from the second picture the outlet would want to be on the floor under the tub!? Can't you just hard wires the motor like gets done with dishwashers?

[BSAKing]

right side panel comes off, but it is above the bottom of the tub, so no good for spreading mortar. The outlet is on the wall recessed level with the joist. The motor is all wired with a plug - not suitable for diy wiring. Iy just plugs in.

[BSAKing]

$108 + tax is the price at home depot on a gfi for my panel. 15a, single pole, 110v.

[BSAKing]

mmm - the motor is rated for 15 amps calling for a 15 amp circuit.

[BSAKing]

Duh! Dummy me - I strung a 20 amp cable, and I have a 20 amp 240v GFI from an old hot tub installation. I should just be able to use one phase of that for my circuit! If I have a 20 amp circuit, whether I am running a light bulb or a 15 amp device off it is irrelevant, as long as I do not exceed the limit of that circuit. (smacking forehead...!). One problem down ....

[Bob F]

Does that really work? I would think that a 240 V GFI would look for different currents in the two legs, causing it to trip. Will it really work with just one leg used?

[John Grabowski]

*I typically install one or two 20 amp 120 volt circuits for a whirlpool tub depending on whether there is a heater attached or not. I mount a regular 20 amp receptacle (Or 2) near the access panel in a 4" square box attached to the wall studs. It is not always easy, but I try to keep the receptacle box from interfering with possible pump servicing while at the same time keeping the receptacle box accessible. I install a GFI switch (Or 2) somewhere else in the bath room such as a closet or behind the door or as a last resort over the countertop to protect the outlet(s) for the tub. I do this so that it is convenient to reset the GFI instead of having to go to the electrical panel or pry open the panel on the side of the tub.

I usually bond the tub with a solid #8 from the pump lug to the nearest hot and cold water pipes. I clamp onto both pipes and if there is a shower head I clamp onto that pipe too. There is no need to bring the equipotential bonding conductor back to the panel.

Read articles 680-71 and 680-74 and also read the manufacturer's instructions.

[Michael B]

I had some slope to the floor, and used grout to even it up, then I put a layer of thinset down, then put a panel of 2" foil-backed foam down, then the tub in place and quickly filled it with two garden hoses, and watched the extra grout get pushed out. I left the water in over the weekend, got back and siphon-drained the tub Monday night, removed the tub and cleaned up the "removed" grout, and there was never a doubt about it being solid enough. I wanted the foam to be at the bottom because I didn't want heat being transferred away. My wife appreciates that. But I like the idea of doing it with expanding foam. It would have been quicker, I could have taped plastic to the bottom to prevent the foam from attaching to it, in case I ever wanted to take it out. Not likely.

Hey, wife prefers a long soaking bath with Epsom Salts. She hasn't even insisted that I connect the pump. Too many have already told her how the water gets cold quickly when the pump is running. Two big pumps sitting in the garage, candlelight and dimmed light in the bathroom.

The world is good.

[BSAKing]

I just thought I would report back that I lumbered my wheel barrow into the bathroom and mixed up the mortar. What I did is trace the tub outline onto the floor since that is where it needed to be supported. Making it not too soupy, nor too solid was not that difficult. I piled it on and then roughly smoothed it with the shovel. Then placed the tub on it. By just sliding the tub back and for a little on the stringers it settled right in and is really solid.

I have the wiring installed and like I said I ran a solid I think #8 back to the panel. To me it does not seem like a great idea to just bond it to water pipes.

Now on to plumb it all in....

[John Grabowski]

I just thought I would report back that I lumbered my wheel barrow into the bathroom and mixed up the mortar. What I did is trace the tub outline onto the floor since that is where it needed to be supported. Making it not too soupy, nor too solid was not that difficult. I piled it on and then roughly smoothed it with the shovel. Then placed the tub on it. By just sliding the tub back and for a little on the stringers it settled right in and is really solid.

I have the wiring installed and like I said I ran a solid I think #8 back to the panel. To me it does not seem like a great idea to just bond it to water pipes.

*Doing what you did with the mortar is how I usually see it done.

The solid #8 wire is not a ground wire. It is a bonding wire installed to equalize the ground potential for the metal surfaces of the tub similar to the bonding for a pool. The ground comes from the outlet. Get some water pipe ground clamps and connect that #8 to the water pipes feeding the tub or it won't pass inspection. This is a code requirement.

[BSAKing]

Ahhh - gotcha - Thanks for the clarification!