I’m helping someone remodel a bathroom. He’s got Hardibacker up and wants to paint the section of the ceiling rather than tile it. How well will plaster adhere to the Hardibacker? Can we use a setting type of joint compound for this? I’m the supposed expert on this, but I haven’t got a clue. Has anyone tried this or heard of it being done?
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I don't remember if I've skimmed compound directly onto hardibacker, but I've painted it successfully and I've skim-coated over paint.
So I can't see how you could go wrong by priming it (I would use 100% acrylic or oil) and then skim-coating it. Prime it again using the same primer before painting.
DCD,
Won't oil primer react with cement products in the hardi and soapify? (lack of better term)
Seems like someone mentioned in old thread to only use Acrylic latex on Cement board products.
I don't know.
I've always used acrylic (latex) paint on cementitious material since it works so well. I probably should not have recommended oil-base primer as an alternative since I don't have experience with it on this kind of material. The reason I thought of it is because this is a bathroom where high moisture may be present and oil blocks moisture from penetrating much better than latex.
Maybe someone else will come along and contribute additional experiences.
Good point--the word you were probably looking for is "saponify" and it makes sense that since soap is made by reacting oils and fats with base, and that since concrete is basic, it may react with the oil based paint, it might be a problem; but it seems like I've heard of people painting concrete block and concrete slabs with oil-based paint without problem. Don't really know--maybe if the o.p. asked at a paint store, they could advise him.
Can we use a setting type of joint compound for this?
Yup. Have used both durobond and easy sand lotsa times when the tile layout changes. Use the mesh tape and just float it out.
Jeff
Buck Construction
Artistry In Carpentry
Pittsburgh Pa
Plaster should work just fine over the cement board. A bonding agent like PlasterWeld would be a good idea, especially in a shower. Moisture and cement usually ends up in efflorescence, but maybe not on cement board since its made to be in wet environments. Don't know for sure.
Had my neighbor just skimcoat plaster over some painted drywall that was all messed up, cracked, sand textures, and full of holes. Painted on the pink stuff and he white coated it and trowelled it out.
Pete Duffy, Handyman