I am an IT guy and have ignored the plaster problems in my old
townhouse-style home. The previous owners white-washed everything
prior to the sale. 6 years later I need to repair the plaster.
Essentially there are cracks where the ceiling and walls meet in about
50% of the corners in
wait for it
my entire house. So easily 20 cracks if not more.
I also have a major 4 foot crack with some folding/bulging in an
upstairs hallway and a large 2 ft bulge/crack in my basement.
3 years ago I repaired drywall (not plaster) after electrical work and
overall the repairs worked and still look good.
I have no experience with plaster and my parents had recurring problems
with plaster, plaster repairs and leaks, so I'm hesitant to start.
Would Crown Molding be a reliable way to cover up these corner cracks
or should I be concerned that in a house like this, with known
shifting, crown molding could become an issue. I have never seen
problems with crown molding in my neighborhood, fyi.
But what about the other cracks? can I repair a 1x4 ft patch with
reasonable success or the 2 ft square patch? I also don't believe
these cracks were caused by water. I believe it was shifting between
my house and the ones attached on either side.
I found instructions like:
Do those make sense or are they leaving out critical details?
Thanks for any advice and other info.
First of all, I'd like to commend you for wanting to fix the cracks
rather than wanting to tear out the plaster and drywall the whole
thing. Some people will tell you that you are better off drywalling
because you will always have problems with plaster. That has not been
my experience. Unless the entire wall is falling in, I think it is
better to fix the plaster than to rip it out and drywall it. And it
sounds to me like your house it not at that stage. And besides, if you
want to live in a house where everything is perfect, then you shouldn't
be living in a 100 year old townhouse.
Ok, editorial opinion over.
Putting up crown moulding will certainly hide the cracks between the
walls and ceiling, and if you are willing to do the work and will like
the look when it is done, then go for it. A quick and easy option,
assuming the plaster is not pulling away from the lath, and the cracks
are narrow (say < 1/4 inch) is to just caulk the crack so that future
flexing will not reopen the crack. Another way is to finish the joint
as if it is drywall by applying drywall mud and tape in the usual
For areas where the plaster is pulling away from the lath, but is
otherwise reasonably sound, the use of plaster washers is highly
recommended. Try to sink screws through the plaster washers into studs
if possible, if not possible, then at least sink the screw into the
lath rather than into the key between the strips of lath. Then you
will need to put drywall mud over the plaster washers to hide them when
you are done.
For cracks in the wall or ceiling surfaces that are not at a corner,
then cutting out with an inverted V and filling with plaster is the
usual fix. Again, if there is any plaster pulling away from the lath,
then use more plaster washers. If the section is badly cracked and
pulling away, then it is usually best to just rip out the section of
plaster and redo the plaster starting at the lath. As you are ripping
out unsound plaster, you need to know when to stop ripping, because if
you don't, then before you know it, you have ripped out a whole wall.
Your 2x2 section all of a sudden turns into a 4x4 section. Redo these
sections with a basecoat and a finish coat of plaster. It is also best
to use a bonding agent such as Larsen's plaster weld:
http://www.larsenproducts.com/plasterweld.htm When you plaster a whole
section like your 1x4 or 2x2 sections, you may need to practice a bit
first. And if the final result does not have a satisfactorily smooth
surface, then you can just put drywall mud all over everything and sand
it smooth. Even though that is "cheating", there's nothing wrong with
doing that (assuming that you have keyed the new plaster properly into
the lath), it will hold up just fine and no one will be able to tell.
Wow! thanks for the speedy and detailed response.
Yes, all the cracks are thinner than 1/4 in.
To clarify, when I used the term "bulging" I now know I meant the
plaster was pulling away from the lath. That occurs in one noticeable
spot along a 4 ft crack.
Some of the plaster effects in my house are curved and appear modified
during the Art Deco era, so yeah, not going to drywall the entire
I'm going to start small and work from there.
Some hints, based on suffering through the first room in my house, and then
getting smarter as the work progressed:
1) Not sure if all plaster (powder mixes) act the same, but the stuff I used
got warm and began to "set" in the pan if I mixed it too much. So, work in
small batches, and mix ONLY until it's all moist. Then, apply right away. It
helps to have two or three pans. When you're done with one, set it aside and
let the plaster residue dry, while you continue with a clean pan. You don't
want dry chunks of plaster mixed in with the fresh batch you're about to
mix. The pans will dry quickly if you scrape out most of the residue. For
the remainder, hold upside down over a trash can and smack them.
2) If you find that you need to remove big chunks right down to the lath, be
sure to apply the plaster in thin layers, and then wait at least a day for
it to dry. This might take longer if the wall you're working on is cold.
And, trying to help it along with lamps or hair dryer will not go well.
Don't ask how I know this. :) Just be patient. Watch the color change as it
3) Sanding will obviously create dust. Buy or borrow a shop vac that can
have a hose attached to the exhaust. Put the hose out the window if
possible, so the exhaust doesn't blow around the dust you haven't gotten to
yet. Or, at least aim the hose away from the area you haven't vacuumed yet.
4) If some cracks are in areas where you feel there'll be more flexing, or a
door slamming nearby, prepare the crack according to the instructions on the
web site you already looked at. Fill the crack with plaster, but leave a
groove 1/8" deep. Cover the crack with a piece of mesh drywall tape,
pressing the tape into the groove with your fingernail or the blunt end of a
small tool. Flatten the rest of the tape against the surrounding area. (The
tape's sort of waxy, and will stick without help, assuming you remove any
dust first). Finish the patch job with drywall mud.
5) If you end up using screws for some repairs, be aware that lath can be
very weird to screw into. It's gummy and dense (or something), and will
sometimes want to bend away from the screws, rather than allow them to dig
in. So, pick up some long drill bits in the appropriate sizes, and drill
pilot holes. Incidentally, this characteristic of lath is one reason why
people who slam nails into plaster walls should be fed to the sharks. The
pounding can make the lath bounce inward and separate from the plaster, and
then you have the mess that you've already seen.
6) When the plastering's all done, be sure to give it at least a week to dry
before priming. As mentioned earlier, you'll be able to see the color
change. On interior walls, you can often FEEL the temp difference as one are
dries before another.
Sure. But be prepared for some headaches trying to line up the edges. If
the house settled enough to crack the plaster, it also settled enough to be
out of square.
What shifting? This is an old house, it should be done settling by now. If
these are new cracks then you need to find out what's started moving.
Rectify that problem before you waste your time patching what's only going
to crack again.
What're we talking about here? An actual town house or row house? I'm from
Baltimore originally so I know the difference. Calling those tiny little
houses "town houses" doesn't elevate them into the more solidly built as
'houses in town' for folks from the country. Row houses are often made from
inferior brick and rather lacking in engineering. If you've got problems
because of the houses next to you then your next call should be to a
In my place there were developing cracks between the wall and ceiling.
One (ok a couple) tubes of latex caulk applied to the corner fixed it
right up. The caulk flexes so the cracks have not opened up again.
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