The reason "it seems like a good test" is because it is a good test.
there's no "assuming" going on here, it's called experience...unless
the plaster is in terrible shape, a push pin won't push in.
Depending on where the house is & the quality of construction it could
go either way. I've seen lots tract houses from the 50's & 60's, some
drywall, some plaster, some skim coat plaster.
Drywall (at least in SoCal) pretty much took over the market by the
end of the 60's.
Why the curiosity about wall type?
My house was built somewhere in the 40's if not earlier.
When I had the bathroom remodeled in 1978 (I think)
I saved all that gorgeous lath that they took out of the walls.
Have used it for so many little projects! Like building a screen
n front of the trash area in back, and building screens for under
the back porch. Sigh! They don't make 'em like they used to...
Take a receptacle cover off and you can usually see. If there is lath, you
can probably see the edges.
Age will give you a hint. If the house is 100 years old, chances are it is
plaster unless it was re-done. If it is less than 50 years old, 99% chance
it is drywall. It was invented in 1916, but did not become popular until
Take off a couple of electrical receptacle covers and look at the edge
of the opening. If drywall,
there are most often, but not always, some sign of what it is ... an
edge of a seam showing or a
nail pattern along a seam.
I thought for quite some time that our condo must have plaster walls, as
I could not find any sign
of nail pops or other of the usual defects. I was wrong - just a darn
good job in a part of the
building which hasn't, apparently, settled at all.
I just knock on em. Drywall sounds like knocking on drywall, knocking
on plaster sounds like plaster. But if you are not sure, go to an
unconspicuous place in a closet and scratch down through the paint
with a nail or pick. If you hit paper then you have drywall, if you
hit hard white plaster with no paper then its plaster.
Is there such a thing as plaster board? While renovating the upstairs of my
1942 home, I could see the back side of the walls in the stair case. There
was no lath and the stuff crumbles when I try to nail into it to hang a
picture. It seems to be a plaster sheet product. It may have had a paper
backing, I don't recall.
Old version of what they now call 'blue board' plastering. Instead of
lath, they nail up panels with a rough surface, or even a grid of small
holes o give a key, and skim coat that with plaster. Much less labor
than nailing up miles of lath a strip at a time, and doing 2-3 coats of
Very durable when properly installed, but not real DIY friendly for
modifications, repairs, or hanging pictures. Would have been quite
common in a 1940s house. Sometimes still used in high-end custom houses
and restorations- TOH used to show it almost every year.
As to how to tell- I always use the knuckle rap and warm palm tests.
Drywall almost always sounds very hollow in the middle of stud bays when
you rap on it, plaster usually doesn't. And drywall feels warm under
your palm in seconds, since it has a paper surface. Plaster sucks the
heat out, and feels cooler longer. Failing that, pull an outlet cover
and probe outside the edge of the box with a tiny scewdriver- the paper
surface layer will be easy to see.
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