From: jeffz@cray.com (Jeff Zais)
Subject: Re: Patching Ceiling Plaster Cracks
Followup-To: misc.consumers.house
Organization: Cray Research, Inc
Date: 7 Jan 93 08:07:05 CST

Here's the summary of responses to the reqest for hints on
patching some ceiling cracks.  First, the original posting:

|>
|> I'm about to paint the parlor ceiling in my 100-year old Victorian.
|> There are some minor cracks in the lath and plaster that I'm going
|> to patch before painting.  Any suggestions on how to proceed?  Any
|> products that you can recommend or warn everyone about?
|>
|> Some of the books I've read suggest enlarging a crack into a
|> dovetail shape so that they'll hold the patching compound better.
|> This seems counterproductive to me since the cracks that exist
|> are really pretty small right now.  Any advice is welcome.  I'll
|> summarize mail responses, but feel free to respond here on the net.
|>
|>
|>                                                Jeff

Here are the three responses that appeared on the net:

============================================================
NET #1 (Patch with Fixall, or apply 1/4" sheetrock over all)
============================================================
You can patch (and keep patching), or you can sheetrock over it and
get no more cracks. If you haven't sheetrocked before, there's some
learning involved there too, and you may not want to make a
(presumably) high ceiling your first sheetrock project! Neither of
these alternatives is much fun; consider getting used to the cracks. :-)

If you patch, enlarge the crack until you reach the point where the
plaster is adhering decently. Clean up the edges with a utility knife.
Brush out the dust. Spray the area with water to help your Fixall
adhere. Dab in Fixall somewhat BELOW the level of the surface,
beveling the edges up toward the surface. Let that dry. Then mud over
it, and feather it like a sheetrock joint.

If you choose sheetrock (which I do now, having tried both
alternatives), use 1/4 inch. Locate and mark the joists. Have some
extra friends and ladders to help you lift the sheets. Some people
recommend a sheetrock 'jack' which lifts the sheets up for you. I will
unquestionably try to find one of these next time.


============================================================
NET #2 (Patch with mesh tape and drywall compound)
============================================================
Here's what I've done in my 90 year old lath/plaster house...

I don't enlarge the crack.  I scrape any lose stuff out and then cover
it with dry wall tape.  I use the fiberglass screen type (not the
paper type).  I go over that with pre-mixed drywall compound.  I treat
it just like a drywall joint -- feathering it out and
sanding/sponging.  The crack won't come back through the tape.  If you
do a good job with the feathering, it looks great.

Where my plaster was really pulling away from the lath (it moves in
toward the lath if you push on it), I replace it with drywall.  In
some places, I just replaced a section of the ceiling.  Again, you
have to use drywall compound to make it look just like the rest of the
ceiling.

I have to add that doing a good job with the drywall knife requires a
lot of practice.  It's very frustrating at first.  But it can look
real nice once you get good at it.


============================================================
NET #3 (Not really patching cracks, but a useful idea for plaster repair)
============================================================
A fellow who was working for me on the rehabilitation of an 1870 house I
own
came up with an interesting technique to save some of the plaster that was
a
bit loose.

He took simplex roofing nails -- the ones with the big plastic disks (used
for
attaching roofing felt) -- and replaced the nail with a drywall screw.  He
drove the things into the loose plaster, reattaching it  to the lath. 
Then, he
applied several coats of drywall mud to mask the screw and disk.  Where
there
were cracks, but the plaster was solid, he used drywall mud over mesh tape.

In this way, we were able to save almost all of the plaster, including some
curved surfaces that can't be duplicated in drywall.  I much prefer plaster
to
drywall.  Besides better sound-deadening qualities, it just has more
character
than a perfectly-flat surface.


Now, a summary of the mail responses:



============================================================
MAIL #1 (Patch by scraping and applying plaster into crack)
============================================================
Hey Jeff,

I've been doing the same on my 62-year-old bungalow.  I've been
scraping first to get a somewhat level surface, then applying plaster.
After it dries you just sand it smooth with fine sandpaper.  You can
even smooth it with a wet cloth.  It's been working well for me.
I can't see making a small crack larger.  Good luck!


============================================================
MAIL #2 (Use mesh tape if the crack is large enough)
============================================================
Prepare for a stiff neck, back, etc.
Seriously, I found ceiling work to be the worst.
It helps if you have a scaffolding that can position
to a reasonably comfortable point.

I would recommend enlarging the crack unless its
"solid" -- you don't want to patch over loose plaster.
Also, it helps getting the patch material in as far as
possible.  Also, if the crack is large enough use
fiberglass mesh tape for this purpose (I've found
you have to search around for a place that carries this).
On the other hand, if the cracks are *really* small,
you could probably get away with just painting them.



============================================================
MAIL #3 (Use mesh tape and three coats of drywall compound)
============================================================
Hi, here's what I've done on my 110-year-old cracked plaster walls --
use a self-sticking fiberglass mesh tape and drywall compound. Place a
piece of the tape over the crack and then do the old three-coat (over
three days) application of the drywall compound. It's worked like a charm
for us, and so far no cracks have reappeared (the tape is supposed to
help minimize this problem). In the past I have tried opening the cracks
and applying regular plaster, but the end result for small cracks is that
the plaster fell out.

For plaster moldings (rails) around the ceiling, I've used a mixture of
drywall compound and latex paint and brushed that into cracks. Our
plasterer recommended this, and it's worked pretty well. Takes a few coats.

Good luck!




============================================================
MAIL #4 (Just put in some white caulk)
============================================================
On advice of the Boston Globe's Handyman (daily column, people call in
with questions and he answers them in print), I used white caulk to
fill in a crack in one ceiling.  We suspect that the crack in the
ceiling was caused by either the shifting of the building or the
vibration from our heavy outer doors.  Since the caulk is somewhat
elastic, it really did the trick.  Also we were able to easily control
the application of the caulk and wiped away the excess with a rag.  We
caulked about 1 year before painting (laziness) and the ceiling has
been painted for 1 year, and it looks great.  The plaster cracks in
the wall that we had spackled before painting are back (in 2-3 years).
I went back over them with white caulk (the walls are white) and
filled some in.  I didn't have to repaint, and they also look great.
I'm planning to use caulk in the future for most thin plaster cracks.
However, I suspect that over the years the caulk will shrink in size
the way it does in the bath.  I'll probably just reapply caulk at that
point.



============================================================
MAIL #5 (Enlarge to a V-shaped crack, and patch it)
============================================================
  Jeff,

   I've heard the same thing about enlarging a ceiling crack so that
  it has a V shape to it.  My brother followed this method, and his
  ceilings look great.

  You said you had cracks in the lath?  My lath (in my 98 year old
  colonial) is 1/2 inch below the plaster, that would be more than
  minor in my book.  If you really meant the lath (wood slats) have
  cracks, and are therefore sagging, you have a whole different
  problem.

  Good luck!


============================================================
MAIL #6 (a brand name recommendation)
============================================================
        try "FIX ALL" for your cracks. The stuff dries pretty fast, doesn't
        expand, and can be sanded/painted, etc.


============================================================
============================================================
Thanks to all who replied.
Newsgroups: misc.consumers.house