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Repairing plaster walls. HELP!

GaryD's picture

I'm about to paint some walls in my fathers house, and it is plaster walls. Can I repair plaster cracks with fast setting drywall compuond? As well there are a few bad patches that need to be cut out, again, can I patch larger holes with drywall and then coat with compound? Any assistance would be helpful, as I am a carpenter who has done enough drywall work but I have done no plaster work. Thanks, Gary

(post #92052, reply #1 of 8)

Durabond is your friend for little splits. For big holes, you might look into poor mans plaster, aka structolite for filling the deep holes. If you can run a DW knife, you can run a trowel. Durabond sticks to that too. Not the best solution, but it answers what you're asking.

" Blessed are the forgetful: for they get the better even of their blunders" - Nietzsche

Real trucks dont have sparkplugs

(post #92052, reply #2 of 8)

Gary,

You'll have no problem at all with Durabond, or any other setting type compound.

There are commercially available gypsum bonders that will make this stuff stick to plaster, paint, or pretty much anything else on the wall except dirt and grease.

Rock on. <G>

DRC

(post #92052, reply #3 of 8)

I would like a bit more info on Durabond.

(I did go to their web site).

Is Durabond used as a repair/patch basecoat ?

In another words, can it be spread and smoothed/textured as a final repair coat if the walls are to be painted over ?

I bought several cans of PlasterWeld and would like to know if I should still apply it and then use Durabond for patching.

And, finally, is Durabond commonly available at places such as Home Dump ?

I don't recall seeing it or maybe I never paid attention.

Had to go to a specialty house for the PlasterWeld.

Thanks !

Alan

(post #92052, reply #4 of 8)

The hard durabond is getting hard to get.  It's the best too.  Final coat stuff you can use the easy sand or even ready-mix but for the patch coats you want the old hard 90 minute durabond and use some glass tape too.  The most important thing about repairing plaster cracks is too get the delaminated and pressure stressed finish coats knocked off.  The best way to do that is to use a small hatchet (shingle hammer works good) and chop into the surface of the wall chipping out the areas around the cracks (light quick chops, not too deep, chipping the finish coat only).  The soft areas will be obvious and the pressure ridges will sound hollow when you tap them.   Make enough space to bury your tape in most areas and also remove anything that is too soft or ridged up too high.  At the ends of the cracks you will have to taper off and just finish them with mud (no tape).  If the brown coat is crumbly surfaced it is best to use a rewettable glue to help hold everything together.

(post #92052, reply #6 of 8)

I would like a bit more info on Durabond.
(I did go to their web site).

Is Durabond used as a repair/patch basecoat ?  Because it's pretty tough joint compound, it can be used for plaster repair.  It technically isn't a basecoat plaster, though (because it's not plaster).  For that there are a number of different varieties on the market.  I use USG Red Top Wood Fiber basecoat plaster, since I can use it in a lot of different applications (i.e. metal lath, wood lath, gypsum lath, masonry, etc)



In another words, can it be spread and smoothed/textured as a final repair coat if the walls are to be painted over ?   Since it's a joint compound, yes.  Durabond is a little difficult to sand, but if you use a heavy grit first (100), it'll knock high spots down well.  The trick is to apply it needly, don't leave huge ridges, boogers, and the like.  Prime it before painting, however (I prefer oil-based Kilz, either regular or low-odor).  For a finish coat, though, I prefer "Easy Sand" setting joint compound because... drum roll... it's much easier to sand.


I bought several cans of PlasterWeld and would like to know if I should still apply it and then use Durabond for patching.  You could, but I don't know if I'd bother.  When I repair plaster with plaster I do, but for a crack I'm filling with Durabond, just wet down your basecoat/finish coat plaster with a plant sprayer or brush dipped into a cup of water.  PlasterWeld and/or water help keep the Durabond/plaster from drying out too quickly, due to the old plaster sucking out the moisture.  This premature drying will cause the repair to be weak (the plaster/compound will tend to crumble). 

And, finally, is Durabond commonly available at places such as Home Dump ?
I don't recall seeing it or maybe I never paid attention.  In my area (Detroit suburbs) it is available at Home Cheapo/Dumpster, as well as BLowes.  Look for the grocery bag-colored bags in the aisle with the drywall and joint compounds, stacked alongside the white "Easy Sand" bags.  In my area they no longer stock the 20-minute set, only Durabond 45 and 90 (45 and 90 minute set).

Had to go to a specialty house for the PlasterWeld.  Yup, me too.  For the plaster there's only one or two places that carry even the more frequently used stuff (i.e. USG Diamond finish plaster, etc)

 

Anyway, FWIW, I've done hundreds of plaster cracks (not really a source of pride, however).  Usually unless I have a gaping hole (bigger than quarter size, with no gypsum/wire lath/wood backing), I do the following:

1.  Go at it with my handy-dandy utility knife, the type that you can easily swap out blades.  Gouge out the crack to the bottom, and taper it out so that it ends up a V-shaped channel.  You go through blades quickly, but this seems to work better than a hammer and chisel, power grinder, etc.

2.  Wet down the basecoat/finish coat plaster once or twice pretty well.  Note that sometimes the latex on the wall may start peeling when you do this.  To avoid peeling, pre-prime with oil-based primer around the repair.

3.  Mix up Durabond 20/45, press it deep into crack

4.  Apply mesh drywall tape.

5.  Repeat 3 and 4 depending on the depth of the hole.  Because the Durabond sets up pretty quickly, these steps can be repeated about every hour (I go about an 1/8" or so at a time) such that a 3/4" deep or so gouge can be almost perfect within a few hours.  Make the last application flush with the finish surface of the wall. 

6.  Wait overnight, since the Durabond will shrink, albeit minimally.  (A deep 3/4"-1" crack will shrink enough that an overnight wait is needed).  Sand any goobers that are sticking proud of the wall. 

7.  Apply Easy Sand (to make getting the final finish easier) to make the patch flush again.  Let dry, hit lightly with fine sanding sponge, etc.

8.  Prime with Kilz oil-based.  If I'm doing a smaller crack, I love the spray-bomb Kilz. 

9.  Hit refrig for beer, stand back and admire. 

PS... Gaping holes call for metal lath, basecoat/finish coat plaster...

Enjoy!

(post #92052, reply #7 of 8)

Can't thank you enough, Burpnboy.

Since I have a house full of walls/ceilings to deal with, I want to dive in fully prepared without having to run to the store every couple of hours for this-and-that.

I will add your note to my collection of plaster related messages I've squirreled away.

thanks again,

Alan

(post #92052, reply #8 of 8)

I've had to do a lot of plaster repairs in my 1840's house. Here's what works for me.

For cracks take a screwdriver or knife and open up the crack a bit, undercutting it. If the edges are loose the keys have broken and you should use plaster keepers (essentially a drywall screw and a flat washer) to screw the edges back down firmly to the lath. Apply some fiberglass mesh tape (this will help prevent cracks from coming back) and apply thin coats of joint compound til it is no longer visible.

For larger openings I screw down any loose plaster and use MD90, a bonding agent, to cover all the exposed lath and adhere the plaster edges, then I finish with joint compound.

Seth

(post #92052, reply #5 of 8)

Are these cracks fine hair line cracks?  If so they will always come back.  Unless you do what I do, repair them as you would usually, scrape, fill with what ever, sand.  Then get Good Bye Cracks(the same people that make Goof Off make it), open some windows and spray as directions on the can.


Used it on sereral jobs the stuff works, go over the areas with a good primer like kilzs. As for large patches I some times use stucco patch for areas down to the lath. Prime with cement bonder first then patch. If it needs to be smooth I  top it. I find the sand in the stucco patch is like rough plaster and it fills faster the difference almost between unsanded grout and sanded grout.