Fixing bubbling plaster (or is it paint?) on vintage sheetrock ceiling.
pizza
| Posted in General Discussion on
Hi. My house was built in 1952 (southeast PA). The drywall is not like the drywall they use today. It is the type that is REALLY rock hard like they made them back then ( i believe they called it sheet rock). I have a small section of it (that I’ve saved) and it seems like it is made of a gray rock type material then has another layer (which faces the interior of the room) of about 1/8″ thick layer of, I guess, plaster? It is very very smooth on that 1/8″ layer. Then there’s the paint/coating on top of that.
The ceiling is sound. The sheetrock itself is not cracked nor has it released from the framing/rafters above. The problem is that the “coating” on this sheetrock ceiling is bubbled in several spots. This “coating” is either many many layers of paint or, in some spots, it seems to be a thick layer of perhaps plaster (on top of the previously mentioned 1/8″ layer of plaster)? When I say thick I mean about 1/16″ to 3/16″. I’ve scraped away the loose stuff as far as that area seems to want to go (until it doesn’t just fall off from my scraping). It peels away easily until it doesn’t anymore (exposing that very smooth layer). Now I have several spots that need to be re-patched. But with what? Ordinary drywall joint compound or plaster? Do I need to seal those scraped away areas first before patching? If sealing, what should I seal them with?
I suspect that that bubbling layer is paint PLUS plaster because I can see the paint layers and the layer below that is more chalky and thick. When I’ve scraped it away there ususally is a very thin layer of brown stuff like maybe a thin layer of I don’t know what. By thin I mean .010″ or less.
Thanks.
Paul
Replies
How large of an area has been scraped? Include photos if possible.
Lots of irregular small areas. I just followed where the looseness took me. Not a big kitchen. By tapping you could hear where it wasn't adhering and where it was tight.
Fairly normal for several layers of old paint to peel off, especially when some of it is oil paint. And if there is any moisture coming from above that could be a factor too.
And what you have sounds like "rock lathe" with a skim coat of plaster -- fairly normal for the era.
First make sure there is no moisture problem (bad roof, leak in toilet on upper floor, etc), then scrape off the loose stuff and re-apply a skim coat of plaster or drywall mud. Then (after the plaster dries) repaint.
Thanks. Will do. No leaks anywhere. I re-insulated that area above that ceiling (there's just attic space) and that sheet rock was as sound as could be. Took out all old insulation, sealed any air leaks, added soffit baffles correctly and brought up insulation to R-39. Nasty job to say the least. It was bubbling even before I re-insulated I just have never got to it till now. BTW, also these sheets do not have lathe above them. They're fastened securely to the rafters. My heating bills were noticeably reduced-yay!
Just curious, what is the difference between plaster and drywall compound in terms of it's makeup and applications and behavior? Where would you use the two interchangeably and where would you use one over the other etc.?
Hi. Another question...After scraping and exposing the previously mentioned very smooth surface, I suppose it would be prudent to sand that smooth surface to rough it up and give it some "tooth" for the drywall joint compound to adhere better?
Hey all, this is really just some context info--not an answer to the problems–but yes it does sound like rock lath. I found an old thread in the forum that talks a little about it and how it was used as a base for a skim coat of plaster (sort of a transitional material between the old full plaster jobs and our modern drywall installations):
https://www.finehomebuilding.com/forum/anyone-ever-hear-of-rock-lathe
Pizza,
I would “prime” the bare spots you’ve scraped with Plasterweld. After it drys I’d use Durabond 90 if the depth warranted and you can apply it real good as Durabond is not hardly sandable. Then I would top coat that with Easysand 45 which allows maybe 20 minutes of working time......don’t use warm water. If you’re not quick enough and have the time, use Easysand 90.
If you don’t want to mix the timed muds, use All Purpose bucket mud.
Kitchen, could be they painted over the old coat(s) without washing the grease or other before hand.
I have this problem, also. Same era of home in NE Ohio. In my house the paint was lifted all through the house a few inches above the base boards. I have just started working with it in the upstairs hallway and just noticed some peeling at the top of the walls. There are only 2 coats of paint then a very smooth plaster wall. When scraping it is very loose and pretty much seems like the whole wall will peel off easily. Could there possibly be lead in what I am scraping off?
The "plaster" does not have a hardness to it. I can rub it with my hand and my hand will be white with dust.
When I get this all scraped off will I need to still skim coat it? I'm don't know how to do that and would rather be able to paint over it with some type of sealer, if possible.
AC,
First, there is a possibility of lead in your paint. Banned in the manufacture in the late 70’s. Encapsulating it and proper work methods while working on it is the usual procedure. The EPA has much info regarding this if they haven’t wiped yet another serious concern off the books. Go to EPA.gov .
Is there a crawl or basement? Damp or wet? What you’re seeing above the baseboard could be moisture from below pushing the paint off or simply breaking the bond between paint and plaster coat.
Upstairs, does this powdering appear at outside walls? Ice dams along eaves can cause efflorescence, suggested by the powdering and release of the bond of paint and plaster to the Rock Lath base.
Once both are cleaned up, powder gone and loose paint, I have had good luck using Plasterweld as a first coat over the bare areas. It’s like a thick milk and will seal and help bond both paint and patch coats of compound.
You will probably have to use joint compounds if there are clear lines on the surface between the built up paint and/or undamaged wall.
Post some clear pictures here for further help if you can.
I think I have 1 pic attached, at least. I'll get a couple more later.
So many products out there. As I am still scraping paint, haven't purchased one yet. I was hoping not to have to skim coat only because my patience level is very low and I don't want to make a career out of painting a hallway. :( so I am trying to get all the paint scraped; not sure if I will be successful.
The more I think about the cause of this peeling paint and referring to the OPs comment I'm wondering if temperature differences caused dampness in the plaster although that doesn't explain the odd places the paint has peeled. What I am working on now is an interior upstairs hallway. I can somewhat understand the walls at the ceiling peeling because the attic was not originally insulated but why at the baseboards on interior walls? Nevertheless, I will be addressing this problem as I paint each room so want to learn the proper procedure because I seriously hate painting!
Regarding your first picture.....
Damp basement, clothes chute in that wall, was there ever wallpaper, what is the room on the other side, so all walls have that texture?
I agree with most of what Calvin wrote except one thing. Do not use all purpose mud, it will not work. I had the same problem on a ceiling. I painted it with Kilz primer and allowed it to thoroughly dry. I followed this with a skim coat of any good mixing drywall compound then sand and repaint with Kilz followed paint. This is a lot of work and is fine for small areas. For large damaged areas, I found it a lot easier to cover the damage with 1/4 inch drywall and finish as as usual.
Thanks for the reply. I'm a bit confused about the different products. Not sure what mud is but will look for drywall compound only. Ha! Really hate the idea of doing a skim coat but I guess I will have to try.
AC
In the bldg trades for over 45 years and have seen your problems more times than I want to remember. Spot problems have a cause. If you can determine the cause, your repair could last a long time. Miss the cause and and the problem returns, you’ll be really cussin up a storm. That’s why I’ve been asking the questions,
Had one customer who liked hair spray a bit too much. Didn’t have too good of an aim.........
If it was my house I'd laminate some 1/4" drywall to the ceiling and start fresh. If it's already bubbling the odds are that as quick as you fix one place another will pop up.