I am in the process of remodelling a bathroom in an older home. The floor is considerably out of level. We will be installing 12″ marble tile on the floor. The floor joists are a true 2×8″ size. The sub-floor is 1×6 tongue and groove board. We need to level the floor because the vanity requires a level floor, it cannot be scribed to the floor. I was thinking of doing a mud job to level the floor, but we will be installing floor heat underneath the tile. The floor in the bedroom where the bathroom meets is 1 1/8″ above the sub floor. What would be the best way to both level the floor without building it up too high (but making it strong enough so the 12″ tiles won’t crack)?
Thanks for your help! Any responses welcome.
Tom
Replies
we releveled my parents 100 year old + house by scabbing on 2x6 to the exsisting floor joists.
Also helped with the multiple cuts made in the old joists by the many remodles from plumbers over the 100+ years.
I agree with jet.
Clear out the old sub-floor. Then replace any pipes you need to. Sister the largest 2x's to the joists to bring level and try to place at a hight to make the finished floor flush with the bedroom. This will depend on water or electric heated floor. Screw down the new sub floor and thin set wonder board to it if using electric. If water heat then use a mud bed and make level. Install the electric mat and then the tile, mak sure to mesh any joints in the wonder board.
Was hoping to not pull up the sub floor. The bays are loaded with pipes ,wires and recessed cans not a lot of room to sister the joist. What about putting down durock installing the elctric heat and using self leveling mix to cover the floor? Would the floor be strong enough to support the 12" marble tiles?
You told us the size of the floor joists, but that is not enough information. You need to determine if the maximum deflection of the floor system meets the allowable deflection for your marble tile.
Deflection is almost impossible to measure without megabucks in equipment, so you'll need to look up your joist configuration in a span chart. (There are span charts online like http://southernpine.com/ ) You'll need to know the size and the span of the joists, then just read the charts.
In some cases, the maximum allowable deflection for tile is 1/360, but for marble, or for almost anything that is 12 X 12, it is 1/720.
That means that if your floor deflects more than its width or length divided by 720, then there is too much deflection. If thats the case, then you need to bolster the joists -- durock and even floated mud bases won't help if the joists are moving.
But there are a few other things you can do to help. Add a 3/4" layer of good quality plywood, nailed every 8" on the center joists, and every 6" at the edges. Then be certain to use the latex additive in your thinset mortar. (DO NOT buy that premixed stuff, not even if they are giving it away.) Using the latex gives a much stronger bond, while allowing just a tiny bit of 'give' to the mortar layer.
Also, be sure to use the grout additive too. (It's a different additive, and you can't use one in place of the other. And again, don't even think about buying premixed goo.) It has the same effect on the grout -- leaves it a bit spongier, allowing some flex.
And finally, when your almost finished, be sure to use a grout sealer. If you don't, you might be re-doing the job in 4 or 5 years.
Unless you're the lead dog, the view just never changes.
I understand the challange you have with the space in the bays of the floor. For something like marble the floor needs to be stiff and not flex.
The deeper the joists are the stiffer they are. If I were doing this job (I have to stand behind what I do) I would add the the joists either by sistering to one side of the joists or adding 1x to both sides with lots of glue and large headed screws with washers to pull it all tight.
Pulling the floor is often a good idea because pipes are old and later replacement is real tough.