bathrooms shower floor question

hey guys,

I have seen countless ideas on how to do this so i'm not sure which direction to go....just which one not to go....(which would be what i just got done ripping out)
Here's the scoop. 100 yo house. upstairs bath was an afterthought built into a bedroom. already know the sources of my water problems, the previous shower was removed because the base had so many cracks it was raining into the kitchen and upon demolition found the plumbing also had minor leaks. the shower area is 36X36. the floor (or subfloor) is 1/2 in thick pine t&g slats. the old base was just slapped in on the t&g, and the floor underneath wasn't leveled (but the base was by screwing to the studs) my feeling is the shower failed because of floor not being properly prepared for the additional weight and towards the door side it wasn't even resting on the floor so all the weight from us stepping in was on the fiberglass. the t&g is surprisingly intact, had my hubby put weight on it in different places and although it's not pretty i don't think it's structurely deficient.
i would give u some pictures but i can't find the usb cord for the digital camera....gonna have to ask the kids when they get home.

our idea is to leave the t&g, use a little self leveling floor compound (looking at roughly 1/2 in difference from front to back), and put 3/4 in treated ply with 30lb roofing felt and then set the shower base. to help from underneath (there is drop ceiling in the kitchen) i could put blocking in between the joists on the sides running perpindicular to give it a little extra stability.
I don't care if the base is a little higher than the existing floor because once the shower is done i plan on ripping out the rest of the luan and sticky tile anyway.

does this sound like a good plan? i don't want to be doing this again in another 5 years...

Steph

The t&g is somewhat unstable and should have plywood over it. But, NOT treated plywood, use exterior grade plywood (Exposure 1). The t&g is unstable in that it will expand and contract on its own in all directions and in this case you want to put a little cement on top for the shower base. So...Install a patch of plywood to suit the location and size of the shower base atop the t&g. Put a layer of plastic or roofing felt on the plywood, just lay it there. Then mix a bag of cement (sand mix) and pile it on the plywood. Set the shower base into the pile of cement and push it down so that the cement supports the underside of the shower base. Of course you'll have the drain to deal with also. Then stay off the shower base until tomorrow so the mix has time to get hard without being disturbed. This will give you a good solid shower base that won't flex and won't be subject to expansion and contraction of the t&g subfloor components.

Bud,

thanks for the quick reply as i am wanting to get the base down here soon. Just want to make sure i follow u. i get the movement of the t&g that makes perfect sense. so I should do the 3/4 ply (NOT TREATED) then the layer of roofing felt, and level after that by sticking the base in regular cement or the self leveling stuff? or does it matter at that point as long as it's level AND good and set in the stuff so it is well supported? this slopey floor has given me fits in several rooms....all fixed using a different method...and...1 more question...as my hubby says "I'm pretty hell bent on jacking this hse up" is there anything i should do different with that in mind? the shower is in the back corner of the hse against 2 outside walls, so i doubt even if we do jack her up that it's going to do much heightwise to the shower floor. most of our issues are relative to the center of the house. i was hoping to wait to do the bathroom, but the poor shower just couldn't make it any longer...

Don't use Self Levelling, that's a different product with a different purpose. Just use cheap sand mix or mortar mix that comes in a bag, mix it with water so that it will stay in a pile when you throw it on the floor. The shower base will then squish the cement into place while filling any voids under the shower floor pan.

The plastic or roofing felt is to keep the moisture in the cement so it can cure properly. Future movement of the t&g from atmospheric changes won't effect the cement and try to crumble it over time if the plywood is there for stability.

Any raising of the foundation can certainly have an effect on the floor positions and elevations.

sounds like a plan to me! this is why i wanted to brain pick before i did something i regretted down the road...i know just enough to get myself in a heap of trouble.... eventually I plan to be leveling out the tub in the downstrs bathroom because the ex leveled that floor..AFTER he put the jacuzzi tub in. Live and learn i guess. I will let y'all know how it turns out, but I'm fairly confident I can follow directions to a successful install