# What types of walls are these?



## jheavner (Sep 1, 2008)

Our home was built in 1947 and portions of it have been remodeled using drywall. However, there are other places that appear to be plaster. Here's the weird thing, in the closets I can see nails, especially in the ceilings, and in the rooms, there is a distinct seam that runs around the room about waist high. I wouldn't think that plaster over lathe would have either nails or a seam but I don't know. Is this likely a drywall like board that has had plaster skimmed over it? If so, would it be relatively easy to replace with regular drywall? Are the studs more likely to be on regular centers and level? The closets in particular look pretty rough. The inside corners are open and the surfaces are not even close to smooth. If I could tear everything out and easily hang drywall then I would go that route.


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## Big Bob (Jul 27, 2007)

Pictures would help. A picture of a hole in the wall would really help...
but don't punch a hole just for us.

take off a cover plate and inspect the material to the side. If drywall mud is tight to the side of the box... try to get behind this to see the material behind. This area could have been patched with joint compound or you may have a (rockover) 

Your plaster walls might have been covered by drywall (rockover).

Know that old time framers knew the plasters would make everything straight.. So they didn't care if the studs had a crown or belly. 1947
you might have rock lathe..and plaster..

If you remove the plaster to studs (can be a lot of work...messy,,,dusty, and lots of debris), but great time to rewire and insulate. You need to check that the studs are straight enough for drywall or fir them out.

The above is why plaster often is (rocked over).


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## jheavner (Sep 1, 2008)

I know the downstairs is straight drywall. I've knocked two holes in the wall to for coax drops. In the upstairs I know the closets, at least, have some type of board material because the nails are clearly visible. I'll see what I can do with the walls in the main rooms.


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## Maintenance 6 (Feb 26, 2008)

Rock lath was installed as a base for plaster and would be nailed in place. Rock lath panels are 1'x4'x3/8", then a finish coat of plaster was installed over them to make a continuous wall surface. Drywall could have been plastered over to achieve the same result. In 1947, before drywall screws, these products would have been fastened in place using what my grandfather always called "blue head" nails. My house was built in 1948 and had rock lath/plaster walls. A selling slogan in the late 1940's for rock lath/plaster was "Knock on the walls". My thought is that by 1947 it should have been built with milled lumber and should be relatively straight. The problem with the late 1940's construction is that the country was in the middle of a building boom. Some of the lumber was rushed through the mills and there was a lot of twisted up junk used for construction. In some cases contractors took whatever they could get to build houses. I'd pull a closet wall and take a look. If it looks like it was surface planed and the studs measure about 1-5/8"x3-5/8" then you are probably not going to have too many issues to drywall it. If it's rough cut 2x4 studs, then who knows?


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## jheavner (Sep 1, 2008)

So if I have rock lathe can I easily remove it (easy being relative to lathe) and replace with drywall?


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## Maintenance 6 (Feb 26, 2008)

Easy is a relative term. . It will be very heavy with the plaster coating, but after you have it started it will come off. Don't stand under it. How tough it will be to hang drywall on your existing studs and joists is impossible to tell untill you know what conditions exist.


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## jheavner (Sep 1, 2008)

That's what I'm afraid of. I'm worried that the studs won't be on standards centers or that they won't be level. The one wall appears to have a bit of a bulge right now. I think the closets should be relatively simple just because of their smaller size. Maybe I'll open one of those to get a better idea of what's underneath.


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## Maintenance 6 (Feb 26, 2008)

you can use a stud finder to get an idea of the centers.


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## jheavner (Sep 1, 2008)

True but I bought the cheapest stud finder I could find and it struggles with the plaster walls, especially when there's HVAC and the like behind the walls. A buddy has one of the fancy ones that detects electrical, HVAC, and studs. I should see if he'll let me borrow it.


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## Nestor_Kelebay (Jun 17, 2008)

JHeavner:

Think twice about removing that plaster and replacing it with drywall.

The mass of a wall is the single most important factor in determining how much noise you can hear from the next room. You see, in accoustics there is something called "The Mass Law" which says that:

a) for every doubling of the weight per square foot of a wall or ceiling, or

b) for every doubling of the frequency of the sound hitting a wall,

the sound transmission through the wall is reduced by 6 decibels, or to 25% of it's previous value.

The reason why is because of the extremely simple way sound travels through walls and ceilings:

The sound wave hits the wall or ceiling and makes it move. The movement of the wall or ceiling recreates the sound wave on the other side of it. You hear the recreated sound wave, not the original.

So, if you have heavy plaster walls instead of light drywall walls, then the wall won't move much when hit by a sound wave, and that means that the recreated sound wave will be of a much lower amplitude (meaning "quieter").

Also, the more mass a wall has per square foot, the more inertia it has, and the less able it is to change it's direction of motion rapidly. This is why heavy walls filter out high and midrange frequencies much better than light drywall walls do. It's also why when there's a party going on in an apartment somewhere else in the building, you hear the low frequencies only, and not the higher frequencies. So, you hear BOOM-BOOM-BOOM, but it's not until you get close to the offending apartment that you hear the higher frequencies and recognize what song is playing.


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## jheavner (Sep 1, 2008)

I understand what you're saying about plaster walls and their ability to filter noise but I don't think I have "heavy" plaster walls. I can see the nails popping out of the walls which would lead me to believe the walls are just skimmed with plaster over dryboard and aren't that thick. 

I really have two objectives and I'm willing to listen to any solution. 

#1, I would like to get structured, low-voltage wiring ran behind the walls. Right now, the coax and phone lines come from the floor and run along the baseboards. It just doesn't look very good. I understand that I can just fish wiring and I would do that except for #2. 

#2, The walls just don't look very good. You can see nail pops, you can see bulges, you can see little "clumps" of plaster that weren't smoothed down, there are gaps in interior corners, and so on. My understanding is that it isn't always easy to find someone to do good work on plaster and my fear is that the cost of trying to improve the aesthetics of the existing wall will exceed the cost of new walls. 

Actually, in terms of sound, I would be more interested in keeping the hardwood floors from groaning and squealing.


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