Hi guys
It’s been I while since I was here but that’s good cause it means I’m busy.
Anyway, I got a job coming up where I need to drywall over a plaster ceiling in a house built around 1930 or so.
As usual I found the “Advanced Search” feature less than helpfull but I know some of you guys here in the northeast have been doing this for some time. I need some basic do’s and don’ts for installing DW over plaster on ceilings. I’m sure weight is an issue so I was figuring to use 3/8″ DW but I thought I read some time ago that there is 1/4″ DW also for architechtural type applications. Am I right about that, or is it only a wish?
Anyhow, any help would be greatly appreciated.
Thanks Dan
Replies
Pretty straightforward. If it's loose, secure it. 3/8 is fine, but the thinner you go, the more opportunity you have for irregularities in the surface you're attaching to to telegraph through, so if it's smooth, you're fine, if its not . . .
Find and mark all your joists. After that, make sure you've got long enough screws to go through the DW, the plaster, and into the wood. If you've got fixtures up there, problem solve dropping them beforehand.
"If you pick up a starving dog and make him prosperous, he will not bite you. This is the principal difference between a dog and a man." - Mark Twain
I once used the 1/4" for ceilings and the problem is that because it's so thin there is no softer center for fasteners to dimple into. It's brittle.
stay with the 3/8", adhesive is worth using
some might disagree but I have had success in using plaster washers from McFeely's to hang dw -- when I try to smug the dw, the screw pulls beyond the paper -- If I were you, I'd mark the joists (might even fur the ceiling out and just shoot the fur to the joists) glue dw and use the washers on an as needed bases to snug the dw to the plaster until the glue sets but then you have the issue of is the glue going to hold if what you are gluing to is questionable -- Dudley
I'm a big fan of plaster washers but prefer the ones from Charles Street Supply which have more perforations. http://www.charlesstsupply.com/
I don't have empirical evidence to think they're better than the McFeeley's washers, which I haven't used, they just look like they'd hold compound better.
Also, the instruction I've seen say just run a DW screw through the washer to hold the plaster back. While securing loose plaster along the sides of open cracks I've seen how easily wood lath will split. I've also had many screws fail right before the washer gets snugged up. So I keep a drill handy for pilot holes and have a lot less frustration.
Edited 10/21/2005 11:10 am ET by cynwyd
I do not think you need any adhesives or furring. Works for me without. Screws are perfectly capable of holding the 3/8 up. Heck, it's lighter than 5/8, and screws hold that up.
The main thing is getting the underlying plaster secure. If some sections are bulging, and do not push back, they can just be knocked off. There can be voids, but you want what is left to be self-supporting. Often, plaster ceilings are sagging, and pulling away from the joists (or strapping- as the case may be). Plaster washers are ok for securing loose plaster, but fender washers are much stronger, cheaper, and easier to find. You are going over it anyways, so the benefits of plaster washers are wasted.
You can build a t-brace, and use a jack to push a sagging ceiling into place, then put screws with fender washers through to lock it in place. A drywall lift with a couple of 2xs across it is also good for this.
This is counter-intuitive, but it is best not to screw close to wall edges and corners. "Floating corners" reduce the chances of future cracks. In fact, if you used an adhesive, you would lose the benefit of floating corners.
Edited 10/21/2005 11:08 am ET by csnow
WRT using 3/8 DW on an old ceiling... I maybe missing something...
3/8" DW is not usually thick enough to be used for new ceilings, not stiff enough and will sag. When applying it over old plaster, what prevents it from sagging if the framing/straping is 16"oc and if one isn't using adhesive to an already self-supporting ceiling? Shouldn't additional screws be used in-between the 16" spacing that's OK for 1/2" DW? In that case, screws holding into what?
screws holding onto wood lath after adhesive
>>> screws holding onto wood lath after adhesive
Exactly, very good, that's what I've done in the past and would do again if using 3/8" thick DW.
Maybe I was too subtle and should have directed the question directly to those who suggested simply screwing it into the framing, eg "I do not think you need any adhesives or furring" from csnow.
Not trying to be confrontational or challenging what you're saying, but I don't understand the logic that the thinner DW would hold up without sagging, just because there is plaster behind it/above it , when minimum spec for ceilings is 1/2" when attached to conventional framing. I'm not worried about the new DW "falling" as much as the waves that would likely show up after some time unless the thinner material is well bonded to the old ceiling behind it .
Thanks for anyone who can explain this to me.
Thanks to all for your help.I was out today to start job. It had those ceiling tiles on. It had been so long since I was out I forgot about that. So the furring strips were already in place, tho I had to add 3" dw screws to secure in some(most) areas as there was some sagging.I didn't think about the floating ends so I'm glad I checked back. Half the ceilg above is gone, (paster anyway)so the plaster washers are a mute point on this job. BTW are those plaster washers supposed to pull into the plaster like in dw? If not how would you cover it? skim coat the whole ceiling?I'll probably take the 12' dw advice, I hate the weight but it would get rid of the end seam problem. Had that last week and it took longer than it should have b/c of that. Also about a year ago there was a thread on here about best dw tips and I couldn't find it to save my life. Does anyone remember that thread??? especially the tip about wetting the ends and cinching them down with metal strapping to create your own seam? I was trying to recreate it from memory on some test pieces but I'm missing something here.Thanks for your responses,
Dan019
washers don't pull into plaster, because of the hardness, like they do in DW - that' why someone's suggestion of fender washers would work
fenders don't have the perfs to hold compound
yes you just skim over the washer's thickness, feather it down, it won't show
end seams done off a joist tied to a common ply base will help mask the joint
Whenever possible, I use sheets that willl span the width of the room. That usually means using 1/2" SR.
But I've been using 1/2" on ceilings for close to 30 years without any callbacks, so I don't think the weight is an issue. And its strong enough to pull any slightly loose plaster back up.
I used to use 2=1/2" or 3" roofing nails, but I've benn using screws for a while now. Like someone else said, make sure they're long enough and catch the ceiling beams
Seen it done w/ 1/2 " dw and nailed w/ 2" roofing nails (2 at each location). Old timer said that way less chance of a pull-thru on the nail head. He also ordered 12' to span entire width of room. Said butt seams hard to hide w/ a ceil fixture throwing light at a shallow angle on it. he was right, Looks great, 2 years now.....no problems yet.