Setting tub in mud

[M3]

I'm not sure if this is the best place to post this, but I'd appreciate your comments.

I'm planning to set a drop-in airtub (36 x 66X18), but when the rough plumbing was done the drain pipe (2" abs) only has 2.5" of concrete over the pipe. The concrete is rebar reinforced (drilled into old slab) but nonetheless only 2.5 inches of concrete is covering the pipes. The drain is off to one side so the majority of the slab is 4" thick.

I am also planning to set the tub in Sand/Concrete mix and am wondering if I should raise the height of the tub podium and add another 1.5" of concrete under the tub and then do the mud base, or if the 2.5" slab will support the tub.

Thanks.

[spryde]

I suspect the slab will hold up the tub easily.

If those are the interior dimensions of the tub, your tub will hold 185 gallons of water which weighs around 1500 lbs. 1500 lbs spread over the roughly 12 sqft that your tub touches the floor means you have roughly 125 lbs per square foot or about pound per square inch. If your floor can hold you, it can hold the tub.

Now this is based on logic and some past experience. Someone else may have more experience (and better experience ...) and point out the flaws in my thinking.

SP

[M3]

Thanks Spryde,

The demensions were exterior and the tub only holds 50 gallons and the base of the tub covers 8 sq ft. So using your logic and experience, I really shouldn't have anything to worry about. I appreciate your insights - I just don't want to damage the tub or the plumbing.

[spryde]

No problem. I just set a 60x29x16 tub over a 3/4" plywood subfloor in a 2" mortar bed. The floor didn't budge when the tub was filled. If John Bridge ever came back online, I can finish the research for the tiling.

SP