Repairing plaster veneer over drywall

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  #1  
Old 11-22-07, 06:12 PM
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Repairing plaster veneer over drywall

I removed the paneling that was covering the lower half of my kitchen walls and discovered (a) the paneling was lightly glued, and (b) the walls are drywall (blueboard) with a plaster veneer. (House was built in 1969.) Along the glue lines, the glue pulled off pieces of the plaster in some places. And a section of drywall under the kitchen window needs to be replaced entirely due to some old water damage.

If this were "normal" drywall and joint compound, I could do the work myself in a heartbeat, but I'm intimidated by the plaster (especially after reading some earlier threads in this forum).

Here's the question: Can I use regular drywall (non-blueboard) under the window, mud it and tape it "normally", and use joint compound/spackle to repair the glue damage to the plaster,

OR, do I have to continue using plaster (which means that I probably won't be able to do-it-myself)?

Thanks.
 
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  #2  
Old 11-23-07, 05:33 AM
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Welcome to the forums!

Hopefully one of our plaster pros will be along later with better info

I've patched a little of the old tradional type plaster [w/lath] using drywall materials but I've never had to repair any blue board plaster that I recall.

You should be able to replace the damaged portion with regular drywall but you would want to shim the drywall out so it's almost level with the plaster veneer. That way you only have to skim a thin coat over it to level it all out.

I've had good luck repairing tradional plaster with durabond and would assume that would hold true for plaster veneer.
 
  #3  
Old 11-23-07, 08:21 AM
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I'm not a "pro", per se, but I've sure done my share of repairs of all kinds, in old (1800's) and new rentals that have seen old plaster fall off walls, bulges, cracks, college student fights with holes put in sheetrock or plaster walls, leaks through ceilings - you name it. Small and huge areas. I have years of experience doing all this and don't feel intimidated by any of it. I actually enjoy it, to see how perfect I can get it without having to sand it, nor to be able to see the repair when done. I have done lots of experimenting with techniques and methods.

If you use the powder-in-a-bag Durobond 'setting type' mud, that actually has Plaster of Paris as one of the ingredients. It sets up by the same principle that concrete sets up (with water and the releasing of heat), as opposed to simply curing by air, the way the readimix sheetrock joint compounds are that are in a pail. So, you can actually apply a heavy fill coat and not have to wait an eternity for it to dry, and then shrink, the way the pail stuff does.

I find that Durobond 90 (90 is the setting time in minutes, with variables to that, of course, due to heat and humidity and the temp water you use, etc.) is good. The Durobond 20, for example, can start to set up on you before you are through mixing (if you are a novice.)!

Clean the loose plaster off with perhaps a wire brush at those bad areas and use a duster brush on end of vacuum. Then mix and apply. Be sure not to gob it on to where it is raised. Bear down on it with your mud knife. Better to add a 2nd and 3rd coat rather than attempt to have to have to sand off this type Durobond, because unlike the pail stuff, this stuff gets much harder.

If you want, you can also do this: Do the first fill coat in Durobond. Then do the topcoating with pail mud. That way you CAN sand it.

Expect to get small air bubbles that surface, especially when you go over the repair for a 2nd and 3rd time. If you keep trowling with the knife, as it starts to dry, you can pop the tiny bubbles for the most part. Then when dry, just scrape down the bubbles and tightly skim with more mud or even use lightweight spackle. I personally like to use the spackle. I actually even put it in my mud pan and trowel it on with my broadknife, just where needed, the way I do mud. It costs more than mud, but it is very effecticve and fast, and doesn't shrink back down into those pock marks (bubble pops).

If you have to section out and replace that sheetrock, just replace it with any type. Too many theories abound out there. The theory is that it is good to use green treated sheetrock in kitchens and baths. WE have put up regular sheetrock in even the most steamy college bathrooms that are small, and have never had problems. Sheetrock and latex paint breathes, and you really don't have a problem, IMO. [There also is advice, based on theories also, on how to prepare engines for the winter. Well, every year, I do nothing and my lawnmower starts up the first pull. So I take many theories with a grain of salt. I look at actual evidence. Another one are theories on taping sheetrock for repair work, and I've done lots of experimenting with leaving the tape off, in certain circumstances, successfully.]
 
  #4  
Old 11-23-07, 10:53 AM
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Smile Thanks!

Durabond 90, it is; thank you both.

(Now I just have to convince the *other* decision-maker in the house that it's OK for me to do this... I had to remind her that I taught myself to be a stone mason a few years ago for a deck project, and that turned out great.)
 
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Old 11-23-07, 03:22 PM
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The only way you learn is in doing. I think doing a little skim coating should be easier than stone mason work. Tell the other half that if she does not think it came out smooth enough that she can sand it to her liking.

You can mix the stuff right up in a mud pan. I use a plastic 2 inch putty knife for mixing it in one. The reason is the 2 inch putty knife fits the bottom, cross ways. I prefer to add warm water as I seem to get less lumps that way, and it mixes creamier, quicker. The drawback is that the warm water sets it quicker. But since I'm quick, it doesn't matter. Everybody has their tricks for mixing. Some put water in the pan first. That method never worked for me that well. The real key is what yo want to accomplish is to permeate the powder. If water is on the bottom first, there it stays; and if water is ontop the powder, there it stays. The key lies in how you first start the permeation. The better you do that, in the beginning, the less lumps you will fight. If you get lumps, you have to mix and mix and mix. Some people wait a bit and then continue to mix. But I never have to much of a problem. I just pour in about 1/2 a pan of the powder, then hold it under a faucet or tub spout with the aerator off. I fill it with water almost to the top. Then I move the mix around in the beginning by just jabbing and twisting the putty knife touching the bottom of the pan, to allow the water to permeate the dry powder along the bottom. But do not actually MIX, as the material will come out too thin due to all the water. Once I have done that, I pour out all the water. I hold my putty knife over the top so that only water/gray slurry pours out and not the bulk of the mix. Then I stir til it's finality and add more water or mix as necessary to get the perfect consistency (many trimes now I get it right, right off the bat (you'll develop that skill after a while); toothpaste like, or even a little thicker for deep fill that otherwise might sag when applied on a vertical surface.

There are a lot of tricks you learn working with this stuff. For example, as the stuff cures, right before it totally sets, the consistency becomes exactly like a bar of soap. You can carve off excess at this stage if you discover sags or bulges. You just take say your 6-10 inch broadknife and carve it in a slicing motion. Don't just push the blade; slice instead.

For large projects, to cut down on the repeated mixing, it's nice to have an empty 5 gallon mud bucket and paint stirring attachment for a drill. That mixes the mud just wonderfully! In fact, that mixes ready mix, as well, to the most beautiful fluff, also! You work at your bathtub or utility tub doing the adding of powder and water.

Important note!!!: If you run out of Durobond mud mix in a pail or in your mud pan, you cannot just mix fresh mud up in it without washing out what is in there! Reason: That mud will flash off in the new mix and will cause sand-grain size pebbles to set up and score your beautiful work.
 

Last edited by ecman51; 11-23-07 at 04:02 PM.
  #6  
Old 11-24-07, 02:45 PM
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Like marksr said, just shim the drywall to the level of the blueboard. drywall comes 1/4, 3/8, 1/2 and 5/8 thick. Maybe a combo of two thickness will do. There is a difference in expansion/contraction from the two materials. I would make sure there is wood around the entire perimeter of the repair. Use plenty of drywall screws (use a scraper and make a countersink dibit in the plaster to avoid cracking the plaster) and paper tape... not mesh. I have never had a problem mixing drywall with plaster as long as there is wood around the repair. Using plaster for repair would be difficult to hide the seam. In time there would be at least a hairline crack. This is what I have seen from other plaster on plaster repairs. I never tried it myself. I myself have had perfect results using Durabond and drywall.
 
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