Thread: Newbie - Need to build a platform for a bathtub

Most house construction is simple butt joins and nail guns, so there's nothing tricky there.

Over here (Australia) the solution would be standard 90x35mm pine wall framing with studs at 450mm centres, top and bottom plates, and some braceboard to eliminate the chance of diagonal movement.

That frame would be supporting whatever bearers and joists are required by your local building code for domestic flooring loads. Doesn't matter that you are never going to fill the tub with water, it's still a floor and has to be built to the applicable standards for trafficable flooring.

Depending on the span, you may be able to do away with the need for bearers, or add a third stud wall in the middle to reduce the span to acceptable limits for whatever size joists you use. That'll depend on which way the underfloor support runs, though.

Your local building code may also require that you have a direct load path from the studs to the joists - ie the bottom plate of each stud wall should be directly above and parallel to the joists so that there is maximum load transfer rather than point loads over the middle of an unsupported floor section. This'll require checking to see what exactly you can get away with (here they have to be no more than 1.5 times the joist depth away to be considered as suitably supported).

Your local codes may also stipulate that since it is over one meter from floor level, it requires a compliant handrail, compliant stairs with non-slip covering as it is in a wet area, waterproofing membranes to all surfaces and so on......

Are you sure you can't just dig a deeper hole and recess the pipe a bit more?????