# Is this drywall, plaster, or both?



## wrbrb (Aug 18, 2020)

Noticed some/most walls of our 1952 house are about an inch thick and look like they're made up of two layers. About 3/8 of one texture and then about 5/8 of another, no lath to be seen. Is this two layers of drywall for some reason, or plaster over drywall? Was this common? And what would be the best method for patching - 3/8 and 1/2" screwed together and then mud to make the difference?


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## joed (Mar 13, 2005)

It is plaster with gypsum lath. Between wood lath and modern drywall there was stage where 2x4 sheets of what looks like current day drywall were used in place of the wood lath.


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## ClarenceBauer (Mar 4, 2005)

joed said:


> It is plaster with gypsum lath. Between wood lath and modern drywall there was stage where 2x4 sheets of what looks like current day drywall were used in place of the wood lath.


It is Rock Lath System. See attached sheet for info.


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## Let it Snow (Feb 23, 2019)

Rock Lath and Plaster. 3/8" x 2' x 4' lath boards with plaster on top that will vary in thickness. Some places may be 1-1/4" thick. The finished plaster is straight. The thickness varies to make up the difference in studs bowing and other variables. In the Pittsburgh, PA. area, we still have plenty of plaster companies. They all do hard coat now but almost all know how to repair your plaster because the trade has been handed down through family. To patch, most would mount two layers of plaster board and finish using the hard coat system. Raw plaster must be painted with the correct primer before using regular paint. If not, the paint will fall off.


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## ClarenceBauer (Mar 4, 2005)

Let it Snow said:


> Rock Lath and Plaster. 3/8" x 2' x 4' lath boards with plaster on top that will vary in thickness. Some places may be 1-1/4" thick. The finished plaster is straight. The thickness varies to make up the difference in studs bowing and other variables. In the Pittsburgh, PA. area, we still have plenty of plaster companies. They all do hard coat now but almost all know how to repair your plaster because the trade has been handed down through family. To patch, most would mount two layers of plaster board and finish using the hard coat system. Raw plaster must be painted with the correct primer before using regular paint. If not, the paint will fall off.


Rock Lath size Chart.


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## wrbrb (Aug 18, 2020)

Thanks for all the information! Owning a home from 1952 has turned out to be really interesting, from this rock lath to low voltage light switches and EMT everywhere to aluminum siding and galvanized plumbing... interesting time for home building.


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## wrbrb (Aug 18, 2020)

Could this be patched with two layers of drywall or one layer of drywall with wood furring strips or shims, taped, and mudded?


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## ClarenceBauer (Mar 4, 2005)

wrbrb said:


> Could this be patched with two layers of drywall or one layer of drywall with wood furring strips or shims, taped, and mudded?


Two layers of drywall & setting compound.


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## RichieTee (Aug 8, 2018)

wrbrb said:


> Thanks for all the information! Owning a home from 1952 has turned out to be really interesting, from this rock lath to low voltage light switches and EMT everywhere to aluminum siding and galvanized plumbing... interesting time for home building.


My parents had galvanized plumbing then upgraded it to copper in the early 80s.
I bought a fixer upper that was built in 1961. It is very interesting stuff -- I've got vinyl siding ... over asbestos siding!
... and the "bandaid" jobs the previous owner(s) done have been awful! I went to replace a ceiling fan and it was screwed directly into a stud through the plaster in the ceiling -- no electrical box!
Most of the walls are made up with what is in your picture. I gutted the bathroom and installed green drywall and cement board -- it was all double layer stuff like you have. Most of the rest of the house still has that though -- it seems very strong! In places I have had to do what you're asking -- I've done two layers of drywall and setting compound.


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## u2slow (Feb 9, 2012)

wrbrb said:


> Could this be patched with two layers of drywall or one layer of drywall with wood furring strips or shims, taped, and mudded?


I grew up in a house like this, and my Dad was a plasterer to boot. Ours was 3/4" overall mostly.

For patches, he would use 1/2" drywall and mud it right up to 3/4". For wall major changes, he'd feather the transition down to 1/2" drywall with mud over 2-3 feet. No big deal.


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## jeffnc (Apr 1, 2011)

wrbrb said:


> Could this be patched with two layers of drywall or one layer of drywall with wood furring strips or shims, taped, and mudded?


I don't know if it's the "best" way, but I can tell you I've done it with furring strips/shims and it has worked well. I my case the thickness was 3/4" and I cut 1/4" shims from 2x4s on my table saw to get the wall in line for 1/2" drywall.


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## wrbrb (Aug 18, 2020)

For the "setting compound" mentioned, will USG all purpose joint compound in the green container work, or is there a different product I need to look for?


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## ClarenceBauer (Mar 4, 2005)

wrbrb said:


> For the "setting compound" mentioned, will USG all purpose joint compound in the green container work, or is there a different product I need to look for?


Setting compounds are a dry mix & most come in a bag.
Being you have existing Plaster it is best if you use the setting compound.


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