I have a 1950's brick home in Virginia with true plaster interior walls and
it's time to repaint a stairway wall. The paint is in pretty bad shape. It
flakes off easily with the blade of a chisel, with all layers of paint right
down to the plaster skim coat coming up. It's as though the paint never
really bonded to the original plaster. This failure to bond seems to have
occured only on the exterior walls so I wonder if the lack of housewrap and
thus colder surfaces might explain the peeling. The task before me is to
either scrape all the old paint off or perhaps to paper the wall. But I'm
also wondering about adding a layer of 3/8" sheetock directly to the
plaster. The plaster wall is quite cold to the touch and I wonder if I'd
gain some insulation, especially if I added a layer of some sort of very
thin insulation before adding the sheetrock. Back when our home was built,
contractors just put lath directly on the brick or block without any
additional insulation. I know I'd have to remove molding around windows and
at the baseboard, but that's not a huge project. I'm not sure how I'd handle
the joint where ceiling meets wall because the ceiling goes off at a 45
degree angle, not the normal 90 degrees.
Would I gain much feeling of warmth with the additional sheetrock? What
product would be best for the thin foam insulation? Any new products better
than plain sheetrock which I know doesn't have much of an R factor?
I would blow insulation in walls, you will need 2 holes one near
bottom one near top of each stud cavatity, remove all the lose
plaster, prime area with kilz oil to help adhesion, then skim coat
with drywall compound. it adheres great.
this elminates all the moulding issues, can result in a excellent job
and insulation saves energy.
I would look into closed cell foam for that wall its a self vapor
barrier, about R6 per inch, theres a minimal expanding type for this
I would take a close look for water problems in this area that may be
causing the peeling plaster, either wall siding or some sort of roof
flashing problem. Mght be worth popening the wall at the worst place
and taking a look, you might find a leaking drain pipe or something. I
did this recently here for the same reason and found a bath leak,
actually 2 that were somehow migrating into this wall nearby and
causing plaster peeling
cavities)- they were still being built in that era. OP's comment that the
lather may be directly on the brick or block would tend to support that
MDB, please enlighten us- Stick frame or masonry walls?
Yes, the construction is all masonry. Brick facing with a block core.
Plaster lath attached to the block interior surface. The only voids are in
the blocks. I did go up into the attic to see if I could see any leakage
issues. Nothing. Nor is there any obvious leaking happening on those
interior walls. It's the entire cold wall surface where the original paint
flakes away from the skim coat. So I don't think injected insulation is an
option for me.
During the 50's, it was very common to build without insulating.
I get the impression that the lath and plaster are applied directly
to the brick face. Have you considered easing a small drill bit
through to the underlying brick to determine thickness, removing
the plaster and lath, using an adhesive to secure the right thickness
of Tuff-R to the brick, and then similarly attach 3/8 drywall?
The Tuff-R is foil-backed on both sides, would give vapor barrier and
insulative property, and you wouldn't have to change trimwork. And
the nonflammable materials on both sides of it would satisfy its
terms for installation.
Sorry, I had intended to mention nails or screws to attach
the drywall to the strips the lath was attached to, but said adhesive.
Ya know, if you remove the plaster and lath, and put Tuff-R
between the strips, you could cover it with 1/2" drywall and have a
comfortable wall ready to be painted.
I'm really not interested in tearing out that entire wall. Just too much of
a job when the benefit would really only be seen if I did the entire home
But what about my original question, the wisdom of applying thin foam (maybe
the 1/2 Tuff-R Michael B mentioned) with a 1/2 inch layer of sheet rock on
top. Adding that full inch does create issues for windows frames and
baseboard moldings but I could probably work it out. Would still like to
find something even thinner than the 1/2 inch Tuff-R though.
OK, this is how I see it.
The paint was serving the function of a vapor barrier.
And it failed.
As the vapor migrates, so goes the heat.
Whatever you do, make sure your inner wall surface can
get at least 2 coats of latex semi-gloss, so that it has a
perm rating of 0.99.
foam board topped with 3/8 in. drywall. That should be easily installed
although you would have to build out your window frames and baseboards. Be
aware that plastered walls can be very unlevel and out of square.
Of course, the thinner your insulation, the less R-value you are
gaining. When you get below an inch, I would start to question
whether it's really worth the extra trouble. That being said, if you
want something very thin, you might look at the stuff they sell as
underlayment for hardiplank type floors. I think it's a closed cell
foam, it comes in rolls about 4 feet wide and it's about an eighth-
inch thick, IIRC. Dunno what the R-value would be, or even if the
package would tell you. -- H
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