Hello all

I am in the process of redoing my very old house. I am ready to finish up a bathroom I recently gutted. The floor is quite unven. I took care of the floor in terms of shoring up the joists and such. But I want to level the floor while adding strength to the floor.

My subfloor is 3/4" fir flooring tongue and groove, the joists are supported every 5' by a large beam. The floor is uneven up to an 1" in spots. I want to lay slate down. The use of deck mud sounds like it might be the best fit.

Does anyone know if using deck mud and slate will be to heavy for my floor. Also do I have to lay the tile down on the mud floor directly on it before it dries out. The idea of having to lay my tile while keeping it square scares me if I have to do the whole bathroom and if it has to be done quickly. If I use a grid system and lay out the mud in different regions would I have to worry about the contact joints between the different mud areas and installing a membrane over them.

Parts of my bathroom would have the mud quite thick 1 1/2" while other parts would only be 1/2" thick. Since the floor is so uneven

Any feedback on thickset beds would be great.

Cheers

Toubob

If the low areas are a small percentage of the total area fill them in with a few shallow layers of thin-set. Then sheet over it with
plywood. Just be sure your t&g has no movement. You have to fix that underneath, not on top. Beware of raising the floor so much that you don't create other issues, such as when you set the toilet or transitioning to the next room.

Your mud floor must be fairly consistant with thickness in order for it to work properly. Be sure when you mud the floor that you place a vapor barrier on the wood floor the add a layer of expanded metal mesh overlaping at least three inches and nail every six to eight inches to secure. As far as if the floor can handle the weight, cannot help you with that, but you must understand that if the floor can flex underfoot, it will fail. so if you find that you feel movement on the sub-floor before you place your mud down, you must increase the strength or place additional joists under the sub-floor to prevent this movement.

Why not cut out the old T & G and figure out why this floor is so unlevel in the first place and fix that instead of trying to do somethig that very well may fail.
I also agree slate is a very poor choise for a bathroom. It's brittle, poris so it stain easly and will need far more maintance then tile would.