Renovating Bathroom. House built in 1947.
Took up old ceramic tiles.
There is an old mortar bed underneath, about 1 1/2 inches thick. It is cracked in several places, but seems stable. I can put a great deal of weight on it with no evident deflection.
Question is, do I need to totally take out the old thickset? I am thinking of repairing the cracks, adding a thin backerboard with thinset on top, and laying the marble tiles on top of that. What do you think?
If I take the old thickset out, I am worrying about structurally compromising the floor under the bathtub, since there is no way I want to take the bathtub out.
Comments?
jna
Replies
Thin backerboard ... like 1/4 or 1/2" Hardie .... does not add any strength to the floor. It provides a nice smooth surface for the tile ... and accepts thinset well.
I would sawcut at the edge of the tub and remove the mortar bed. Or, if I was doing a budget job for you, my client, I would remove the loose mortar and fill/float the floor with a high strength grout ... NOT ceramic tile grout, but the stuff that is used for filling floors ... sometimes used for anchor bolt holes. Then set the hardie in a proper thinset bed on top of that.
Just had a second thought ... what makes you think the mortar bed goes under the tub? I bet it doesn't. Can you cut a viewing hole through a wall from an adjacent room?
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
Edited 8/6/2004 11:58 pm ET by Ed Hilton
hmmmm......
Not sure I am after strength, like I said, the floor seems extremely stable, mostly I was thinking to use the cementboard to get a flat, stable surface, and provide something to knit the pieces of the mortar bed together. Seems like some cheap insurance.
BTW, you are right. Ther mortar bed under the tub is separate from the mortar bed under the tile. I took another look. So I probably could take out the mortar bed under the tile, and replace it with plywwod and cementboard. Is it really worth it? Will the plywood be strnager and more stable?
tnx for yr advice.
jna
Under the mortar bed is another loose bed about 4"-6" thick.
If you remove the top mortar bed you have to remove the whole thing down to 1"x6"s that rest between the beams. Then remove the 1"x6"s and sister the beams to gain the hight.In the meant time the tub gets loose and you will need to remove the tub too.
Your best bet is to wet the floor and set your cement board on thinset.
YCF Dino.
seems like you may have saved my life...
jna
I am with YC on this one. But if the stuff seems real crumbly on top that's not good. I would use a sharp points chisel and break what is loose. If you tap on a portion, you can tell if it is separated from the bed below. When you have swept and vacuumed the cr-p out, wet the bed and float a sand mix type mortar with latex admix to make flat and level. If you do a real good job of that, you can put the tile on that and dispense with the backerboard.
ditra.
find some place that'll cut ya a small piece...
Jeff
Buck Construction, llc Pittsburgh,PA
Artistry in Carpentry