plaster repair

[Haldeman1773 (WavyGlass)]

Based on my observations in old houses, and the scope of my own past work, it seems the typical repair for cracked plaster is to scrape, tape, and spackle with modern joint compound. However, it seems to me that joint compound is much more brittle and prone to re-cracking, than true plaster. Perhaps there's a better way to make these repairs, but where does the average home-owner obtain and learn to use true plaster products?

[Kashka-Kat]

OK I'll bite, but I suggest this thread go into the How-to section. There are numerous approaches and it would be great to have a compendium of approaches for future reference.

I use a variety of approaches depending on what's actually going on with a wall but never spackle or mesh tape. For cracks where plaster is only cracked but otherwise firmly adhered to the wall - if its very tiny hairline crack I solve the problem by redefining it as a non problem and ignoring it.

If its wider and more unsightly - I widen the crack making it wider at the bottom, in an inverted V, taking it down to the lath. Clean out plaster dust & dirt - vacuum, small brush and water, whatever it takes. Apply bonding agent (Elmers Pro-bond is one) to lath and sides of old plaster. Apply plaster pushing it in firmly, into the crack and into the gaps between the lath. Wet-sand it down so the crack filling is flush with the wall surface. You may or may not want to put a light layer of spackle over it to get a really smooth surface. Allow to cure for at least a month before painting.

As my plaster guru explained many years ago, the crack will either NOT come back - in which case the mesh tape is overkill. Or it WILL - in which case the mesh tape won't stop it from re-cracking and then you have to dig out the tape to repair it. Either way - mesh tape is more trouble than it's worth - IMHO - and the bonding agent is more effective at bonding the new plaster to the old.

Where to get real plaster - I find it in specialized building supply businesses that sell mostly to trades people. Never have seen it in a big box store. I have seen Pro-bond though - in Menards.

If the plaster around the crack is loose or falling away from the wall this can be addressed by various other approaches including plaster washers and drywall patches.

[Haldeman1773 (WavyGlass)]

We have a ceiling with a few cracks and failing prior repairs. It is still well-adhered, no sign of plaster key failing at the lath. The proposed fix, for this small room (10 x 18'ish) was to install some anchor screw/washers in the center (more to ensure against future failure after adding an addition few hundred pounds of new plaster), and go over the entire ceiling with new plaster, approximately 3/8" thick. I have many concerns with this:

1. They don't want to remove the crown molding, so this will hide part of the profile of the existing crown molding.
2. They're adding several hundred unnecessary pounds to the ceiling.
3. This is going over several hundred years worth of old paints, including latex. I anticipate a bond failure either between the paint and original ceiling, or the new plaster and old paint.
4. Quoted price of $2500 seems awful high for such a small room. I think I could do this repair myself for $100 and two evenings of work.

Am I wrong?

[csnyder (WavyGlass)]

This thread is in the correct section. The howto section is intended for complete guides (perhaps with some discussion afterward), rather than discussions.

At some point, I'll probably start a sticky post with links to discussions of interest based on various topics.

[Kashka-Kat]

No, OP! I don't think you're wrong at all - what in the world are they trying to accomplish by adding that thick layer? If athe crack is repaired and the failing portion patched, then the thick layer over serves no purpose and as you noted creates more problems than it solves (overlapped crown, possibility of bond failure, etc.)

[phil]

here's what I do.
clean the walls well get rid of any calcimine paint (which is water soluble)
fill any big holes using plaster.
use drywall tape but dip it in yellow glue, (wood glue) I thin the glue a little.
lay the tape over any hairline cracks, use a little taping mud mixed with glue to fill any roughness but don't use much mud at this point. use your knife to draw it down flat to the wall. don't build the seam like you normally would with drywall taping compound, you can do that as a second step if you want. for now just draw it down flat with the knife to keep the tape against the wall.
install drywall corner tape if the corners are cracked, use the corners with paper and use the same technique with glue, and a very thin amount of mud mixed with glue, but draw it down tight and flat like with the paper tape.
primer, use good oil based primer so you have a good bond to what's there.
skim coat with drywall mud.
finish with latex, I like the kitchen and bath paint everywhere because it is washable and pretty durable.

I don't agree that drywall mud is more brittle than plaster, plaster is really brittle but drywall mud is softer. Gluing the tape down provides a good bond to stop the crack from growing. Drywallers don't normally take the time to dip the tape in glue but I have done this a lot and never have any problems with tape lifting.

if you mix drywall mud with glue you get a pretty much unsandable surface, much like plaster, so whenever you use glue mixed with mud make sure you apply it by drawing it down completely. watch for any runs/ dribbles and look after them. if you need to fill, like to hide the tape, don't mix glue into your mud because you can't sand it.

[mross_pitt (WavyGlass)]

I'd say it depends on what a few cracks and some failing repairs constitutes. If you post a picture, someone might come up with the proper solution.

It certainly makes no sense to spend lots of money and resurface the entire ceiling for a few cracks or small areas in need of help.

[plastrr385 (WavyGlass)]

As long as the old paint isnt peeling I woould bond the ceiling bas and finish it. Veneer base goes on thin approx 1/16-1/8 in. Same for finish. If the paint is peeling scrape the peeling paint of and do the same. For hair line cracks cover with mesh tape for venner plaster after bonding the ceiling.
Thats what I woould do. 2 bags of base about $30 2 bags of finish about the same roll of tape 5-10.
Hope this helps...my 2 cents!

[Haldeman1773 (WavyGlass)]

As long as the old paint isnt peeling I woould bond the ceiling bas and finish it. Veneer base goes on thin approx 1/16-1/8 in. Same for finish. If the paint is peeling scrape the peeling paint of and do the same. For hair line cracks cover with mesh tape for venner plaster after bonding the ceiling.
Thats what I woould do. 2 bags of base about $30 2 bags of finish about the same roll of tape 5-10.
Hope this helps...my 2 cents!

Where to buy? Never seen plaster products at the local big box or builders supply houses.

I've done miles of drywall taping and repair. Never messed with plaster outside of hole filling. Would need some videos or guidance to get started.

[mross_pitt (WavyGlass)]

You can buy plaster of paris at any big box store for a few dollars.
Some will say that's not right to use, because old plaster had lime, etc..

It works just fine.

Drywall mud is easier to blend in than any plaster. You have to get the plaster just right in the first place if your just doing spot touch ups.