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-   -   Drywall over plaster? (http://www.diychatroom.com/f101/drywall-over-plaster-42173/)

Rob1980 04-10-2009 11:55 AM

Drywall over plaster?
 
How can you attach drywall directly to a plaster wall?

We're currently finishing off a project on our house where we have replaced a drop ceiling with a drywall ceiling, as well as putting in new flooring. In one room we want to put in cornice, but this has thrown up a problem for us. This room is where our stairway begins, and the previous owners installed a layer of drywall that runs up the stairs and into the hallway on the 2nd floor. What this means is that when you get to the bottom of the stairs we have 2 levels of wall depth. Our cornice work would have to run around around these 2 different levels and would look odd. So, our idea is to install drywall so that everything is at the same level. We coped fine putting the drywall up on the ceilings, but that was simply attaching it to the joists, I don't know how to do what the previous owners did and attach it directly to a plaster wall?

It's an interior wall, but I believe that under the plaster there is only cinder blocks, and not any studs. If there were studs then it would be a simple job of making sure we screw through the plaster and into the studs? So, could/should we use concrete screws, or is there some other way to secure the drywall?

pmoe 04-10-2009 06:04 PM

How much thickness are you needing to build out? I'm wondering if you could pay someone to put plaster on plaster and build the wall out to where you need it.

Rob1980 04-10-2009 10:43 PM

The difference is 5/8". We'd really like to avoid having to pay someone else and save some $ since we don't have a lot to spend!

pmoe 04-10-2009 11:22 PM

A google search came up with this -

http://www.diynetwork.com/diy/cda/ar...-PRINT,00.html

I've never used one of those drywall hat/furring channels, so I can't comment. I'm not sure how much thickness they add to the wall. HTH.

Maintenance 6 04-11-2009 07:44 AM

I think I would try some flat head tapcon screws. It would take quite a few to get a good pattern, but in 5/8" drywall it might work.

Rob1980 04-11-2009 08:05 AM

Hmm, I tried google but couldn't find anything! Thanks, but that hat channel looks like it will add too much thickness.

We'll try those screws. Thanks!

Baron 04-11-2009 08:12 AM

If the plaster has some strength also use construction adhesive on the walls first. That way if all your screws don't grab, you will be gaining a friendly glue helper along the way.

bjbatlanta 04-11-2009 01:46 PM

The hat channel is about 7/8" deep. I'm not quite picturing the issue (pictures would help) but if you're going to attach directly to the plaster/concrete block, the tapcons aren't going to work. You have to drill a hole for the screw through the drywall and into the block. Once you break the face paper on the drywall you lose the structural integrity. (The ability of the screw to hold the board to the wall properly.) If you're going to cover it anyway, it would be worth knocking a hole to see if it actually IS block under the plaster. (Not common to have interior block walls.) If it is, in fact block, you can attach the drywall with "tension pins" and liberal use of drywall adhesive IF the wall is flat. Tension pins are small (1-1/8") concrete nails and I think you can get them at HD or Lowes (a drywall supply for sure). Apply your adhesive and just tack enough tension pins to hold the board until the glue sets. If you can't find tension pins, "fluted" concrete nails will work. They are much larger in diameter and you run the risk of the plaster breaking loose from the block before the nail is completely driven in. If the "chunks" if plaster get in between the drywall and the block/plaster you could have a problem. The tension pins are about the same diameter as a regular drywall nail (though a smaller head) and should pull up in the plaster with less risk of "blow out"....

Rob1980 04-11-2009 04:06 PM

Quote:

Originally Posted by bjbatlanta (Post 258374)
The hat channel is about 7/8" deep. I'm not quite picturing the issue (pictures would help)

Sorry, no camera, otherwise I would definitely have added photo's to show the 'issue'. We're basically trying to extend part of the wall out by 5/8" so it's the same depth as the rest of the wall. The reason we can't put up studs (that would be my first choice) is because the wall runs up the stairway, which is already narrow.

Quote:

but if you're going to attach directly to the plaster/concrete block, the tapcons aren't going to work. You have to drill a hole for the screw through the drywall and into the block. Once you break the face paper on the drywall you lose the structural integrity. (The ability of the screw to hold the board to the wall properly.)
I was hoping it would be that easy. We had guys come in to fix up our back door area where we have a foot gap between the back door and storm door. They put up concrete board, right up against the plaster/cinder block. I hoped we could do that with the drywall.

Quote:

If you're going to cover it anyway, it would be worth knocking a hole to see if it actually IS block under the plaster. (Not common to have interior block walls.)
When we took the moulding off there was a plasterless gap and we couldn't see any studs.

Quote:

If it is, in fact block, you can attach the drywall with "tension pins" and liberal use of drywall adhesive IF the wall is flat. Tension pins are small (1-1/8") concrete nails and I think you can get them at HD or Lowes (a drywall supply for sure). Apply your adhesive and just tack enough tension pins to hold the board until the glue sets. If you can't find tension pins, "fluted" concrete nails will work. They are much larger in diameter and you run the risk of the plaster breaking loose from the block before the nail is completely driven in. If the "chunks" if plaster get in between the drywall and the block/plaster you could have a problem. The tension pins are about the same diameter as a regular drywall nail (though a smaller head) and should pull up in the plaster with less risk of "blow out"....
The wall is not completely flat, but is not too far off, so would this still work? Do you think it would be a good idea to do a bit of plastering to get it flat and then do this?

bjbatlanta 04-11-2009 04:58 PM

Quote:

Originally Posted by Rob1980 (Post 258436)
Sorry, no camera, otherwise I would definitely have added photo's to show the 'issue'. We're basically trying to extend part of the wall out by 5/8" so it's the same depth as the rest of the wall. The reason we can't put up studs (that would be my first choice) is because the wall runs up the stairway, which is already narrow.

Kind of "seeing it" now. Sounds like 5/8" board would solve the problem...


I was hoping it would be that easy. We had guys come in to fix up our back door area where we have a foot gap between the back door and storm door. They put up concrete board, right up against the plaster/cinder block. I hoped we could do that with the drywall.

"Concrete board" and drywall are two completely different materials and attachment is not the same for both.


When we took the moulding off there was a plasterless gap and we couldn't see any studs.

Hit it with a hammer and see if it is ACTUALLY block. The "scratch coat" or "gray coat" of plaster looks like concrete. Sometimes on older houses, the trim was put up before the finish coat. It COULD still be a stud wall....



The wall is not completely flat, but is not too far off, so would this still work? Do you think it would be a good idea to do a bit of plastering to get it flat and then do this?

The drywall will tend to "take on the contour" of whatever is beneath it when you fasten it. You will get the same "waves" as the original wall whether it's plaster or bowed studs. The 5/8" is a bit more "forgiving", as it's more rigid and doesn't bend/bow nearly as easily as regular 1/2" drywall. I wouldn't worry about trying to level the existing wall as much as trying to make sure the glue and nails (whichever type you end up using) are hitting the "high spots" of the wall....

bjbatlanta 04-11-2009 05:05 PM

Sorry, some of my response became part of what I was trying to "quote". Should have called my 8 year old for help....


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