I had some water issues in my shower and finally got fed up enough to remove the miss-cut plastic back-splash that previous contractor had tried to install using thin-set.

Upon removal I found a moldy rotten backer panel, so I began to sledge hammer it out with the intent to replace it with cement board. However, as I got further away from the rot, my sledge hammer would occasionally bounce off the wall instead of punching though and it became apparent that there is a very hard plaster over what appears to be blue board.

I continued the demo to the edge of each panel abutting the tub, and tried to stop there, but occasionally some of the joints shattered in a way that removed the plaster covering the blue board above it.

How do I fix the shattered plaster so that my cement board will be flush with the the entire run of plaster coated blue board?

I'm only asking because I've gotten a bunch of mixed answers from various hardware stores

  • The most common is "I don't know" which at least is better than miss information

  • Some say Spackle; but my previous experience is that it doesn't want really want to adhere to the plaster and occasionally will fall out

  • Others have told me joint compound, but I'm not convinced it will be much different than Spackle, nor will it be as hard and water proof.

  • Finally, after insisting that I didn't want to use Spackle, one other associate told me to use Plaster of Paris, which Google seems to tell me is different than veneer plaster, and might set up too quickly.

1 Answer 1


I'd use veneer plaster. Your instinct about joint compound and spackling is on target, and you might get Plaster of Paris to work if you get the mix perfect - but why bother.

My guess is that the people you've been talking to at hardware stores either don't have a clue what you are looking for or want to direct you to something in stock. I'd check at a building supply store (you might get lucky at a big box store, especially if they carry blue board) that contractors in your area use.

Veneer plaster is extremely uncommon in my area, and I can get it when I need it from any of the big chain stores (although I usually have to order it - they never stock it).

  • I thought there might be a reason they weren't giving me veneer plaster. Spackle and joint compound work so poorly I've been using painters caulk to fill some dips. For the project mentioned above, I decided the type of thin-set I bought is cement like enough that I could just use it instead of plaster when I skim coat. It's drying now; I'll let you know how it looks later.
    – virtualxtc
    Mar 21, 2014 at 12:15

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