old plaster, old tub [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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barry pdx
11-01-2005, 11:01 PM
i'm inching closer to the tiling portion of my bathroom remodel and have some questions before proceeding.
the plaster walls are about 80 years old. where the plaster isn't well bonded to the lath i'm tearing out and replacing with sheetrock.
tile will be 3x6 ceramic.

1. lots of the plaster is unpainted. (the original primer coat came off with the mastic that was holding tiles from a remodel). should i prime before applying VersaBond? i'm thinking yes, with latex acrylic primer/sealer. i worry the plaster will be too absorbent if i don't do this.
2. there are sections where the topcoat of plaster came off with the mastic. the topcoat layer is about 1/16" thick. recommendations? i'm thinking either patching plaster and primer OR possibly just use extra thinset when setting.
3. can i use 1/4" sheetrock over the lath for very small sections (say less than 1 sq ft) where the plaster is too damaged?
4. the tub has no flange. i'm going to add a shower head. i plan to improvise a flange with a strip of felt and silicone. the edge of the tub is just about even with the wood lath.
any reasons why i can't leave the lath in place as my furring for the felt and cbu?
5. generic question - must sheetrock really be taped w/ thinset? would primed joint compound fail? i'd like joint compound to be another option for item #2.

thanks all

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11-02-2005, 07:09 AM
1) You don't weant to tile on paint if you can avoid it. Dampen the plaster a bit with a sponge before you apply the thinset.

2) Skim coat with thinset, let cure, then tile as usual.

3) It the area being repaired is not in the "wet area." The wet area is defined as the area behind the shower curtain.

4) You can leave the lathe in behind the CBU and felt.

5) If sheetrock is suitable for the area you are tiling, then drywall tape and compound are also acceptable. See question 3.

Having answered your questions, I offer this unsolicited advice: Go ahead and remove all the plaster and lath, then install backerboard around the tub, and drywall everywhere else. I do not think plaster is a good idea in a shower, and the transitions between repaired plaster and sheetrock will be a pain to do well.

barry pdx
11-02-2005, 12:30 PM
thanks bb.

the demo has taken me much much longer in trying to preserve the plaster on the dry walls (at least where it's still in great shape) than if i'd done a complete tearout. but i strongly prefer it to wallboard and i'd like to think that going to all that trouble to preserve what i can will reduce my karmic debt. or at least make my next project easier :) also by preserving good plaster i'm avoiding extra plaster/sheetrock transitions (assuming that the tearout would otherwise only have been the areas to receive tile)

i've been reading this forum long enough to know how to do the tub/shower area, but i've been feeling a little unsure about how to proceed on the plaster.

i'll probably need to remove a bunch of the lath from the tub/shower anyway for niches but i suppose i can still use some of those pieces vertically along the studs for my furring.