Tub install question

[jbiddle]

I'm about to install a drop-in Jacuzzi acrylic soaking tub. It has 6 support pads on the bottom, but my plan was to support the tub using just the outer 4 pads to make it easier to level. The support will be by two 2" x 6" x 34" laminated oak boards that I can plane down to whatever final thickness I want. The boards will rest on the 3/4" underlayment, span two floor joists, and end a few inches short of the outer wall support structure. My question is that in deciding on a final support thickness, how much of a gap should I leave from the outer flange to the granite surround? My guess was to leave about a 1/8" gap and use a 100% silicone caulk to seal it up.

[hj]

The only support the boards will supply is the greater of the distance between the joists or the pads, so it makes little difference if they are longer than that. BUT, how are you just "using the outer pads" if the other two are between them? And if they are NOT between them then you also need to support them.

[jbiddle]

The only support the boards will supply is the greater of the distance between the joists or the pads, so it makes little difference if they are longer than that. BUT, how are you just "using the outer pads" if the other two are between them? And if they are NOT between them then you also need to support them.

The pads are arranged with a pair at the head, a pair at the foot and another pair between them (a 2x3 grid). The support boards run side to side, one at the head and one at the foot oc the tub. I suupose I can add some support under the center pair. But what about the gap between the granite ledge and the lip of the tub?

[hj]

The lip can rest on the granite, as long as it is NOT supporting the tub. Or it can be above it if you want to fill a gap.

[jadziedzic]

Tubs filled with water are HEAVY; if you support the tub using only the outside pads you'll probably wind up with a nice two-piece tub when it cracks in the middle.