Any ideas on how to paint celotex?
The shop I've inherited (on the corner of our lot) was finished with
celotex. I've tried painting it, but it is really absorbent. Also, where
there had been water leaks from the ceiling, the celotex is discolored, and
paint doesn't cover the stains.
My intent is to paint it white to brighten up the shop. I've been using a
brush and roller, and I'm considering spraying paint in the future.
You mean the Celotex insulation? If you're talking about the rigid
foam insulation, the manufacturers and code usually require it to be
covered by something like 1/2" drywall. It's basically tinder on your
walls. What exact product do you have? Since your shop is near the
property line (inferring that from 'on the corner of our lot') your
local codes may be more stringent than if it were elsewhere on the
property. Depends on your zoning, etc. More details would be
I think he has a material that was used in the 40s and 50s that was
made from plant residue. In Hawaii (where I was) they used bagasse
which is what's left of sugar cane after being de-juiced. Might have
been spelled "cellutex".
It came in 4x8 foot sheets like drywall and was used a lot for
ceilings. Had a slightly rough surface, very light. I've also seen
it for walls in sheets that had a phony shiplap appearance.
No idea about how flamable it was but I'm guessing it had some sort of
fire retardant incorporated into it.
I have an attached garage with my shop in it. The wall between the
house and the garage is sheathed in 1/2" thick Celotex. Its really
light weight crappy stuff. Holes have been punched in it throughout.
Mice have gotten into the wall and tunneled through the insulation. I
wouldnt recommend it to anyone. But its been painted a very cheery
yellow ever since before I've owned the house for 10 years. So it is
possible to paint it.
BTW, nowadays code requires 5/8" firestop drywall so this past summer
I ripped it all off the wall, did a bit of electrical work in the
wall, and put up drywall. Looks much nicer without the yellow.
I'm pretty sure it's celotex. Not a smoothe surface and very light - it was
white in 1940. It may have been put up for it's insulation value; I thought
it was to provide an interior wall.
I don't know about the code.
It's already been painted with several different kinds of white paint. It
looks better than before it was painted and is brighter but still pretty
I may replace it with wall board, since I'm probably going to rewire the
building, and service to it. If I do that, I'll insulate the walls first.
They aoso made a product called Upsom board which was a white colored
sheet that was commonly used for interiior walls prior to sheetrock
days, and there is also a product called Homosote which came in a
variety of colors but most commonly a grey color which is pretty well
rot proof and was used for sofits and outside porch ceilings as well
as inside walls and ceilings. Both upson board and homosote are
light in weight and available in various thickness when it was made.
Both sucked up paints quick and shellac was a common primer used on it
Bullseye shellac by Zinnser will do it. Available in big box builder
supply stores for about 12-15 bucks a gal. I have used it numerous
times to paint and seal andcover stains on ceiling tiles which are
typical of celotex type material without the asphalt added. Celotex
was an original material put out by Johns-Manville and was made from
processed corn stalks and leaves, and used for insulated sheathing on
homes etc. Usually sold in 1/2 x 4 x 8 sheets but they also offered a
25/32 or 1" thickness in tongue and groove sheets of 24" x 96" as
In the 1940, during the building boom there were a number of products that
competed for the low end market to replace expensive plaster. Most were
lightweight cardboard materials about 1/2" thick, even drywall started out
in this market and won.
The cellulose boards are similar to fiber ceiling tiles that are still sold
today for t-bar ceilings and it is still made as an asphalt impregnated
exterior wallboard to use under vinyl siding or brick veneer, although a
number of better products are in use today.
Thanks for all of the replies.
Since I plan on rewiring the shop (some of the wire is the original fuzzy
fabric coated stuff and some is two wire only) I'll probably salvage what
celotex I can for the ceiling and then insulate the walls and cover them
with dry wall. My wife thinks that's a good idea, I can learn and practice
working with dry wall in the shop. I guess she has plans for the housse that
she hasn't told me about yet.
The shop is 90' from the house and the electric service is under ground. How
deep is anyone's guess. My father-in-law sometimes took shortcuts and
sometimes went way beyond what's necessary for a good job: I never know what
to expect when I look at some of his work. I've been replacing the 2 hole
outlets with 3 hole outlets, but most of the wire is only 2.
I plan on running new service to the building and replacing the 2 glass
fuses with a new service box and probably 4 circuits. The existing 2 means
if both main light fixtures are on, you won't be in the dark if 1 blows.
I'll check with an electrician, but I'd like to have 2 for lights and a
couple of outlets, 1 for my Shopsmith, 1 for ...
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