tub platform

freez · 11-13-2012, 10:32 AM

i am building an 8"(approx finish height) 'wet' platform in my bathroom that will have shower and tub on it.
what is the best (and strongest) was to frame it?
should joists (2x6) be directly on the existing 5/8" t&g subfloor and should i just toenail joists into subfloor or use 'L' brackets OR should it float off of the subfloor with a ledger etc in order to ensure perfect level?
it will have two 3/4" layers of plywood, quick slope on one side leading to a linear drain and no division between shower/tub.
platform size is 5'wide by 6' long towards tub area which is approx 6'x6' with a curved edge mimicking tub shape

hand drive · 11-13-2012, 11:16 AM

maybe frame it so your joists are in line with the joists in the floor, this allows access for the plumbers to put drains, etc without blocking open joist bays and also gives your floor more solid connection to the floor below.make sure the 5/8" subfloor is nailed down real good before you build on it and if you have to shim use construction adhesive along with solid shimming to the floor below. a few angled L brackets can be used too.

mae-ling · 11-13-2012, 11:17 AM

where you from?
Never heard of such a design.

joecaption · 11-13-2012, 11:24 AM

Just attaching the outside rim joist to the studs would keep it in place. There also would be no holes going in the subfloor.
Just using a single layer of Advantec subfloor would be more then strong enough to support a tub and be far more stable and water proof then plywood.

freez · 11-13-2012, 11:33 AM

Quote:

Originally Posted by hand drive

maybe frame it so your joists are in line with the joists in the floor, this allows access for the plumbers to put drains, etc without blocking open joist bays and also gives your floor more solid connection to the floor below.make sure the 5/8" subfloor is nailed down real good before you build on it and if you have to shim use construction adhesive along with solid shimming to the floor below. a few angled L brackets can be used too.

thanks. i always thought one was supposed to run joists across existing but i will consider that. i will be doing plumbing and its over a crawl space so access not that bad
good call on the adhesive and shims!

freez · 11-13-2012, 11:34 AM

Quote:

Originally Posted by mae-ling

where you from?
Never heard of such a design.

toronto. but live in arkansas now. go on houzz.com. lots of 'wet' platform ideas there. i had to raise it because i am sloping to a linear drain and didnt want to go lower than subfloor now.

freez · 11-13-2012, 11:39 AM

Quote:

Originally Posted by joecaption

Just attaching the outside rim joist to the studs would keep it in place. There also would be no holes going in the subfloor.
Just using a single layer of Advantec subfloor would be more then strong enough to support a tub and be far more stable and water proof then plywood.

thanks i will do the rim joist the. good idea. so if rim joist is attached to studs, all the other joist just 'sit' on subfloor? no chance of shifting or movement or flex?
im going to check out advantec. never heard of it. am waterproofing the whole stage and walls with nobleseal but if its deflection is better than ply i will try it

joecaption · 11-13-2012, 11:56 AM

As long as your joist are making full contact with the subfloor, and shimming if needed if there's a low spot it's not going anywhere.
Advantec has been around a long time. It's all that used around here for subfloor. It was designed so as a house is being built if it gets wet the waters not going to effect the subfloor.
I've had to do samples of it as well as reguler OSB and plywood to prove to customers how much better it was.
I took 12 x 12" pieces of each, drilled a hole in them and tied a rope to them and threw them over board at the dock.
The plywood swelled up and delaminated, the reguler OSB swelled up and fell apart, the Advantec looked like brand new.

freez · 11-13-2012, 12:05 PM

Quote:

Originally Posted by joecaption

As long as your joist are making full contact with the subfloor, and shimming if needed if there's a low spot it's not going anywhere.
Advantec has been around a long time. It's all that used around here for subfloor. It was designed so as a house is being built if it gets wet the waters not going to effect the subfloor.
I've had to do samples of it as well as reguler OSB and plywood to prove to customers how much better it was.
I took 12 x 12" pieces of each, drilled a hole in them and tied a rope to them and threw them over board at the dock.
The plywood swelled up and delaminated, the reguler OSB swelled up and fell apart, the Advantec looked like brand new.

thats awesome. thanks for the info. it looks like lowes carries it. i will get that instead

joecaption · 11-13-2012, 12:08 PM

DO not cheap out and fall for there store brand that looks just like it. There not the same!

freez · 11-13-2012, 12:28 PM

Quote:

Originally Posted by joecaption

DO not cheap out and fall for there store brand that looks just like it. There not the same!

ha! i wont!. need to do this right as its the foundation for a lot of tile in shower and under tub

freez · 11-14-2012, 03:45 PM

hey joe. one more design question. when leveling the stage. would you go by actual level or level to the room. actual level will make stage crooked to window and ceiling by 1/2" over 12'
im thinking visually stick to room or tiles will butt up crooked? or i have to make the first course crooked to straighten where they land on winoiws etc