What kind of wall do I have?

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Smythers00

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Hi all.

I'm looking for some knowledge/wisdom here.

I live in an apartment building that was build back in 1967. It's got walls made from some building material that I'm unfamiliar with, see picture attached.

To me, it's reminiscent of drywall in that:

- there's a thin veneer - in this case, a plaster like substance. I say plaster, and maybe that's what it was back in the day. Now it's more like 500 layers of paint and thin layer of drywall compound on top of what's left of that original 'plaster'

- there's a core of a aggregate-based substance. It's definitely NOT drywall. It looks more like cement board. Maybe that's what it was? OH! And around the corners, embedded in this material is expanded steel lattice, which makes me believe this was like a lathe and plaster thing. Except that's definitely NOT plaster!

- followed by a backing of something almost like a thin sheet of rubber.

In any event, the base of these walls around the bedroom windows have this weird thing going on where the 'plaster' tends to get fuzzy or fluffy and falls off (typically over the winter months, so I assume it's a moisture thing), creating a mess that I have to vacuum. Of course the "plaster" cracks and if touched, will fall off too, revealing that cement like core.

I get that this is a problem for the landlord, and I'm not looking for any advice on that.

What I would like to know is:

What kind of wall material is that? I've genuinely never seen anything like that before.

How would one go about repairing that? Specifically, what kind of material would you use?

Thanks in advance.
 

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bud16415

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Hard to say exactly. My guess is a two-coat plaster system over what they used to call plasterboard. They put on a heavy first coat called the scratch coat and then finish coat over that of a finer material. Before the plasterboard they might have used a felt paper or even a tarpaper. Sometimes they used metal lath over the plasterboard. What you are showing is a metal lath/corner bead used for an outside corner.



Then of course all the layers of paint and stuff used over the years. :coffee:
 

Snoonyb

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Walk panels are designed, and by their design, as shear resistance, and the expanded metal lath could have been a design requirement, for shear enhancement.

There are standard gypsolite products for the repair.
 

ChrisAtTech

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I had the same thing at my house. It's what was used after traditional lath and plaster but before just using drywall. Generally, from the 40s-60s but that can vary. The backing is like drywall, called rock lath in this case, and the top layer is plaster. The metal is only used at the corners and joints, so outside corners as well as transitions from wall-to-wall or wall-to-ceiling. It's a pain to remove!

To repair it, the first thing is to remove anything loose and make sure any exposed metal is bent into the wall enough that it's not going to stick out when you're done. Then, ideally you'd do a backing of drywall and go on top with plaster again. Although, you can also use a double layer of drywall and joint compound on top in a pinch. It will never blend quite as well as plaster but is not noticeable for small repairs. For little nail holes and such, I found that joint compound works just fine. If there's a wall or section that has a bunch of cracks/repairs needed then you can also just cover the whole thing in new 1/4" drywall or a skim coat of watered-down plaster (after knocking away the loose pieces).

I also found that a thick nap on any paint roller really helps blend everything together and get into all the divots in the rough plaster surface.
 

Smythers00

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I had the same thing at my house. It's what was used after traditional lath and plaster but before just using drywall. Generally, from the 40s-60s but that can vary. The backing is like drywall, called rock lath in this case, and the top layer is plaster. The metal is only used at the corners and joints, so outside corners as well as transitions from wall-to-wall or wall-to-ceiling. It's a pain to remove!

To repair it, the first thing is to remove anything loose and make sure any exposed metal is bent into the wall enough that it's not going to stick out when you're done. Then, ideally you'd do a backing of drywall and go on top with plaster again. Although, you can also use a double layer of drywall and joint compound on top in a pinch. It will never blend quite as well as plaster but is not noticeable for small repairs. For little nail holes and such, I found that joint compound works just fine. If there's a wall or section that has a bunch of cracks/repairs needed then you can also just cover the whole thing in new 1/4" drywall or a skim coat of watered-down plaster (after knocking away the loose pieces).

I also found that a thick nap on any paint roller really helps blend everything together and get into all the divots in the rough plaster surface.
Very helpful, thanks!
 
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