Repairing a hole in old plaster wall (1940's house)

12 years ago

I'm looking for some help in the best way to repair a hole that's ~3" x 7". The house was built in 1945, and the walls are plaster, but not with wood lathe. The wall appears to be made of 3 layers: right under the paint is a very thin (I'll describe below how I'm thinking of approaching the repair, but please tell me if something won't work well, or if I'm WAY off base with this idea. As I'm sure will be obvious, I don't know a ton about home repairs, but so far I've managed with other, smaller holes/repairs around the house. (No problems yet!)

I was hoping to use the drywall repair clips to attach a support to the existing wall--I don't know if they'll fit over such a thick wall though. So if that won't work, then I'll use a couple of small pieces of wood and screw/glue these as supports to the inside of the wall. Then, I'll place a piece of drywall (or sheetrock?) as the base support and screw/glue that to the wood supports. Then use patching plaster on top of that, anticipating that I'll need a few layers of it to completely fill in and reach the same level as the rest of the wall.

At any point in this, do I need to use that self-adhesive tape to cover the gap between the patch and the existing wall? I'm always afraid to use the tape, because i expect that it will make my patch into a more visible raised area after I apply enough patching plaster to cover the texture of the tape.

If anyone has any suggestions for this repair, I'd really appreciate the input. I've read lots about drywall repair (and I really envy those with drywall now)... but tips for plaster walls are a bit more elusive. I'd like to do a decent job with this repair though--the last thing I want is to have to redo it a year from now.

Thanks!

Comments (11)

sombreuil_mongrel
12 years ago
The wood backer is you better bet. You have three coat plaster over "rock lath" your original finish coat was apparently a colored plaster effect.
Instead of "patching plaster" I'd suggest Durabond for the initial steps to fill just below level, then ordinary green-lid mud and mesh tape to effect the final surface and smoothness.
Casey
brickeyee
12 years ago
Avoid the "patching plaster" it simply does not work well enough to be worth the trouble (inadequate retarder).

Durabond makes a great base material, with Easysand for the finish layers.

Mesh tap and pre-mix mud are NOT a good combination.
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woodbutcher_ca
12 years ago
Hi, I've patched just a few plaster walls. My goal was to cover the hole and make it look good. 3x7 is a small patch. This is how I would do it. Cut a piece of sheetrock 5x9 (thickness isn't important). Score the back of the 9x5 piece 1 inch all around then break the 1 inch piece off the back then peel the 1 inch piece off the front paper. You should now have a piece that is 3x7 on the back and 9x5 on the front. Fit the patch to the hole . It may take some scraping you don't want it too tight. Spread some mud on the edge of the hole and patch and the paper on the patch. Set it in the hole a use a 4 inch blade to set the patch. Let it dry. Most times the patch will be a little lower than the original surface let the patch dry finish as needed.
Good Luck Woodbutcher
brickeyee
12 years ago
"peel the 1 inch piece off the front paper"

This is an amateur method that creates a huge patch area to feather out the paper thickness.
woodbutcher_ca
12 years ago
Hi Brickeyee,
I don't think it is any different than using sheet rock tape. I never had a bad experence doing it that way, so maybe I'm doing something wrong. Thanks for the tip.
Woodbutcher
brickeyee
12 years ago
"I don't think it is any different than using sheet rock tape. "

The tape is significantly thinner than you will be able to reduce the cardboard layer to.

It is a 'quick fix' that relies on excellent feathering skills to conceal the patch, even more so than the thinner paper tape.

I would almost bet money I could find every patch with a light across the face of the wall very quickly.
inox
12 years ago
The Colonial Williamsburg Foundation uses Flex-Tec to repair plaster. The repairs have held for ten years. There is no tape to show.

Here is a link that might be useful: Wood, Concrete, and Plaster Repair using Flex-Tec HV Epoxy
sombreuil_mongrel
12 years ago
$75/tube for flex tec (and I am a big advocate and user of it for it for wood rot) seems like an expensive solution for plaster cracks. The gel epoxy is not quite as sand-able as most of us would prefer for repairs. To put it plainly, it cannot be feathered out by sanding. To overcome that problem, I suppose you could wipe down the area with solvent before it sets, but you would probably have a crack that was somewhat under-filled, and would be visible when painted.
Okay, I watched the video. The demonstrator had to reach behind the wall patch to successfully align the plug. This is not a real-world option, so that application/product claim fails.
Casey
inox
12 years ago
You need a power tool (several are shown):

Here is a link that might be useful: Sanding Flex-Tec epoxy demonstration
brickeyee
12 years ago
"The Colonial Williamsburg Foundation uses Flex-Tec to repair plaster. "

While I have done work in historical buildings (some predating Williamsburg) Williamsburg is not a 'normal' repair by any stretch of the imagination.

They are still building a few houses (as their budget allows) using manual labor completely.

Down to the pit saws to cut up trees after hand felling and retrieving them using animals.

They are pretty far from a reasonable example of repair methods.
inox
12 years ago
The name of the company is Advanced Repair Technology, not Normal Repair Technology.