Hi all,
I need to fill a hole in a plaster wall in a house built circa 1955, and wanted some advice. There was some water damage, and after carving out the soft plaster I ended up with a hole about 6″x12″, as can be seen in the photos. (The source of the water was a leaking roof vent flashing and has been rectified.)
There are two layers in the hole: the first one appears to be a lightweight cement about 3/4″ thick, applied to rock wall, and the second one I think is plaster, about 1/8″ thick. Could I just fill the entire hole with plaster of paris or joint compund, in one or two layers, or would it be better to replicate the original two layers?
Thanks for any advice. I’ve done a fair amount of drywall, but never plaster.
Kyle
Replies
Photo size
Is there any chance you can resize those photos, Kyle?
At least on my screen they are too big to make any sense of. That danged putty knife pretty much takes two full screens to scroll across for example.
But I've had pretty good luck patching/matching old plaster using hot mud.
Thanks for the reply, Jim.
Photos now resized! What is hot mud?
Hot mud is the stuff in bags that has a time on the bag. You can buy 5 minute, 20 ,imute, 45 minute, etc. The time tells you how long you have before it sets. Teh hot mud will fill the hole nicely. Just fill it in at least 2 coats and tape the edges with mesh tape first.
The concrete-like material would be "scratch coat". One formula I find Googling for it is 1 part type S mortar to 2.25 parts sand (though I doubt that many plasterers are that precise). And of course you probably don't want to buy an entire bag of mortar for that hole, so you'll probably want to improvise. Probably some sort of concrete patch material (perhaps with sand added) would work.
Hot Mud
Yeah, like florida said, you buy it as a powder and mix with water. I've heard it referred to as "setting compound" but on the job we call it hot mud. It builds really nicely and leaves a much harder, more porous, surface than regular drywall compound but you use it much the same way. Experiment with it a little though, it's very hard to sand after it dries.
Hey. That hole you're patching is inside the building, right? Around here we usually see that three coat plaster (brown coat/scratch coat/finish coat) outdoors. But there's usually a layer of chicken wire over felt paper too. If it is outdoors, forget I mentioned hot mud.
Thanks for the replies.
I've used hot mud, but didn't know that's what it was called.
Sounds like that would be the easiest way. And yes, it's inside the house.
Kyle
there's two types of setting compound out of the bag-
USG is what I use- Durabond-dries HARD comes 5, 20, 45, 90
Easysand-dries more like compound-easily sanded-same times
Both would work for you quite well.
Kyle,
This might be too late, but hopefully not.
The "rock wall " is the 1st generation of drywall, and was known as "rock lathe" , and came in 16"x 48" sheets.
The scratch coat is the next layer, to patch that I would suggest using the Dura -bond compounds, A.K.A. setting type or hot
mud,(don't use the E-Z sand type ) I would suggest the 45 min. mix which would give you time to work it, but it will still set up
fairly quickly. Fill the 1st coat flush with the scratch coat surface, then use Veneer plaster to finish the final layer flush w/the
existing finish surface, this plaster surface will blend and finish more easily to the original surface and when it comes time to
prime/paint the area, that surface will take the paint/ primer more similarly to the original finish than the E-Z sand type
compounds will.
Hope this helps and is "in time"
Good Luck!
Geoff