"Newser" wrote in message
...
Interesting thought. But would thinset be able to be feathered and sanded
to get a really smooth ceiling??

"beecrofter" wrote in message
oups.com...
On Feb 13, 12:16 pm, "BobAtVandy" wrote:
The ceiling in my outdoor lanai in Florida is drywall with papered and
compounded seams. The paper is coming up in places and there are signs
this
has been repaird in the past so I want to eliminate the problem. The
ceiling is exposed to outdoor humidity, but completely protected from
rain.

I've investigated various solutions, including vinyl beadboard sheets,
wood
planking (v-joint or beadboard), and hardipanel. By far the least
expensive, is hardipanel, but the problem is how to handle the seams.
An
easy solution is to cover the seams with a batten and try to make it
look
decorative, but I'd prefer a completely flat ceiling as I have at
present.

Hardie Products recommends caulking seams, but caulk shrinks, can't be
sanded smooth, etc. So, my thought is to leave, say 1/8" (or less)
crevices
between panels and using plaster (no joint paper) to fill them, and sand
it
smooth. (Hardipanel is very little thermal expansion/contraction.) The
Hardipanel comes in a smooth finish, but it's pre-primed, including the
edges. My questions therefore are primarily as to whether the plaster
would
do the job.

1. Will the plaster adhere adequately to the pre-primed hardipanel?

2. If not, if I simply roughed the edges with a coarse file, would
that
solve it sufficiently?

3. If you think the plaster will work, and assuming it gets a good
coat of
paint, will there be any other long-term issues using plaster?

4. If, instead of intentionally leaving gaps into which plaster could
fill
(and hopefully adhere), I butt the seams and just use plaster to fill
the
fine remaining crack, does that make the solution better or worse?

5. Do you have any alternative solutions that will give me a ceiling
that
has very low long-term maintenance?

Many thanks in advance.

Off the top of my head I'd do the seams with thinset.



I do not think you can get invisible seams. Even if the hardipanel does not
expand or contract any, what it is secured to does. I would give excellent
odds that any non-flexible seam filler will crack. Plaster/stucco or drywall
with taped seams are about the only choices for a continous smooth surface.
I would seriously consider battens in a uniform pattern.

Don Young