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Hello! I have read the thread on adjusting floor elevations between different rooms while trying to tile a bathroom floor. I also have the same problem. The distance I can live with from top of floor joist to finished surface is 1 5/8″
My bathroom is 10′ x 10′ that flexes when you jump on it (joists underneath are long span, on 16″ centers in a 100 yr old balloon frame structure.) I have sistered all joists with new lumber and added cross bracing to stiffen things up a bit – but it still moves maybe 1/16 – to 3/32″ when a 200 lb man jumps up and down on it. ( I should have sistered with 1/4″ steel – then it wouldn’t have flexed! 🙂
I would like to lay down either a 1″ mosaic tile floor or 6″ marble tiles. My concern is having tiles pop because of floor flexion. I only want to do this job once. I’m getting too old and the wrists aren’t what they once were.
I will take out the subfloor (again) and install 3/4 ply between joists. I can put another layer of 5/4 ply on top of this. I am then left with 1/4 to finished height. Tiles or marble will both be about 1/4″ over 1/8 thinset. But will this system flex and pop the tiles?
Or – would I be better off using some type of concrete floor system?
Several months ago, there was a FHB article where the author laid a thin mud bed by using expanded metal lath over roofing felt and stapled to 3/4 subfloor and troweled over with concrete / thinset. Again, raising the floor height with moor subflooring was not possible. What if I used this system, but made the concrete reinforced floor a full 1 1/4″ thick. Is this thick enough to stop flexion in the subfloor, or will it still crack?
Am i better off starting over ( I still have no finished floor down) and putting in steel sisters to stop flexion?
I just don’t want to do it over again in 10 years. How did those old timers do it? I have seen many examples of entry foyers with beautiful 1/2″ mosaic tiles – in wood construction houses.
Thanks for your help!
Robert
Replies
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Rob,
I wouldn't go any thinner than an inch with a mud floor and then use reinforcing and an additive to strengthen the mix.
Another alternative ( which I did in my own house) seeing as you are prepared to pull up the existing floor is to install your ply between the joists ( keeping it down a good 2 or 3 inches to form a floor for a pour right amongst and over the joists ( again reinforce etc ), this should give you a good stiff floor to tile onto.
Rgards
Mark
*Wow, Robb, you really want a "tight" floor. You ask some interesting questions, but I believe you are somewhat misleading yourself. I think with all the work you are considering, you should be concerned with the dead load of the subfloor. Deflection of the floor of 1/360 of the span is standard. 3/32" is not in excess of that, so beefing up the floor to remove even that amount of deflection is not warranted.As Mark has stated, a cement mortar bed of 1" T is the minimum. I would second his proposed method of building your subfloor. And, I wouldn't worry about all the other stuff.I am concerned about your intentions of using only 1/8" thinset to set tile or marble. I suppose if the floor were really, really flat, you could get away with using such a thin layer of thinset, but I suggest a minimum 3/16, preferrably 1/4". For marble, I use a 1/4 x 1/4" square notch trowel and backbutter (skimcoat) each tile. Especially for polished stone.For what you want, I would suggest you disregard the installation method of troweling a thin coat over metal lath. You want something thicker.
*... I'm even less industrious, and would consider using something other than tile! How about a solid sheet of 1 1/2" granite? (Just kidding.) Terrazzo might be pretty cool. A nice wood floor with proper moisture protection? Or set stones in construction adhesive for a slightly flexible connection? Or Pergo? And no jumping in the bathroom.Mark's idea is pretty clever. But the weight? Is the bathroom at midspan?
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Hi. Thanks to everyone for their responses.
Yeah - I got to think about the dead load in that room. The floor joists are only 2X8 and they span 14' . And of course the bathroom is at midspan. (Yeah I know, the max span for that size joist - Doug Fir - is LT 12'. But somehow, 100 yrs ago, they didn't know that.
"Hey, and you want to add 13 psf on top of that - plus an old ball and claw bath tub filled with water with your 200 pounds floating in it??!....See you in the dining room on your way to the basement!" :-)
Got to think this one over some more. Maybe I'll tear out that sagging ceiling underneath and sister on some 1/4 " steel to those joists. How badly do I want that floor?
I saw the greatest floor in Jersey City, NJ last week. Old tesserae marble chips with a Greek pattern around the perimeter. Got to have it.
That's what I was hoping to put in on top of the mud bed. But I might just settle for a Pergo floor and be done with the weight and the worrying.
Hey! What about 3/4 T&G plywood, glued and screwed, covered with 1/2" Wonderboard, with marble tesserae on thinset. That would only be about 4 psf finished. Think that would hold up without cracking?
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No. Not if you can't eliminate the bounce.
*I admire your stubbornness! But i bet you could put all the time this will take into something else in your house that really needs it. There's always something.
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Hello! I have read the thread on adjusting floor elevations between different rooms while trying to tile a bathroom floor. I also have the same problem. The distance I can live with from top of floor joist to finished surface is 1 5/8"
My bathroom is 10' x 10' that flexes when you jump on it (joists underneath are long span, on 16" centers in a 100 yr old balloon frame structure.) I have sistered all joists with new lumber and added cross bracing to stiffen things up a bit - but it still moves maybe 1/16 - to 3/32" when a 200 lb man jumps up and down on it. ( I should have sistered with 1/4" steel - then it wouldn't have flexed! :-)
I would like to lay down either a 1" mosaic tile floor or 6" marble tiles. My concern is having tiles pop because of floor flexion. I only want to do this job once. I'm getting too old and the wrists aren't what they once were.
I will take out the subfloor (again) and install 3/4 ply between joists. I can put another layer of 5/4 ply on top of this. I am then left with 1/4 to finished height. Tiles or marble will both be about 1/4" over 1/8 thinset. But will this system flex and pop the tiles?
Or - would I be better off using some type of concrete floor system?
Several months ago, there was a FHB article where the author laid a thin mud bed by using expanded metal lath over roofing felt and stapled to 3/4 subfloor and troweled over with concrete / thinset. Again, raising the floor height with moor subflooring was not possible. What if I used this system, but made the concrete reinforced floor a full 1 1/4" thick. Is this thick enough to stop flexion in the subfloor, or will it still crack?
Am i better off starting over ( I still have no finished floor down) and putting in steel sisters to stop flexion?
I just don't want to do it over again in 10 years. How did those old timers do it? I have seen many examples of entry foyers with beautiful 1/2" mosaic tiles - in wood construction houses.
Thanks for your help!
Robert