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Remove lightweight joint compound before plastering?

DrBecks's picture

My question is: do I need to insist that the contractor remove all lightwieght joint compound before applying hardcoat veneer plaster?  if not all, then how much? where?

Here is the problem:  the sub that installed the blueboard has also incorrectly put lightweight joint compound all over my original 1956 hardcoat plaster walls and one foot onto the previously deeply textured hardcoat ceiling. My original plaster walls that had a rich paint color are now entirely white under the thick layer of joint compound. (He also taped and floated all the blueboard joints in preparation for paint--not plaster.) 

I have read in a Fine Homebuilding article on veneer plaster that it should not go over lightweight joint compound.  It makes sense to me that this is because the plaster won't stick properly and could fall off, or delaminatein the future. I foresee putting up a picture hook and a 2" chunk of plaster falling off (instead of just dulling my bit, haha!)

Any known techniques of removing unwanted joint compound would be most welcome.  Many thanks for your advice!

Drywall compound will come (post #215443, reply #1 of 4)

Drywall compound will come off with water and ALOT of work.  Won't be much problem to get it off of plaster but you can't get the new board soaking wet...

of course you could also demand the new board be pulled down and the plaster then be cleaned of all the remaining compound.

good advice (post #215443, reply #2 of 4)

Thank you so much for your reply.  That is what we will do, remove the board and start over, and remove the joint conpound from the plaster wall.  It is good to know how easy it is to clean up.  

I'm not sure why removing the (post #215443, reply #3 of 4)

I'm not sure why removing the joint compound that is on the old plaster and covered by blue board is necessary. I can understand replacing the blue board as being easier than trying to remove joint compound from it's surface though. That part makes some sense. 

Lightweight joint compound is (post #215443, reply #4 of 4)

Lightweight joint compound is being over-used! It lacks the hardness and the glue-like properties of USG "green" taping compound. I suspect (though I have no personal experience) that lightweight jcompound will, with time, react adversely to plaster. You can rent a vacuum-attached power drywall sander to clean most, but not all, of the offending jc off areas where it is not wanted. The remainder is sponged off. This won't be easy work, but with patience and sweat you can do it. Rip out and start over in other areas.

If you did not do so, always make sure you discuss your concerns and wishes in depth with your gen. contractor. Repeat, repeat with subs. It is ultimately the gen. contractor's burden to make sure details are accurately conveyed. These kinds of details should be appear in the proposal. I wish you a good outcome. 

Mel Fros froscarpentry.com