Plaster Crack Repair

[tylerlongpt]

1930's home with plaster walls. Cracks in ceiling and walls in living room. I have done quick fixes twice in the past but after a few years the cracks return and the joint compound crumbles out.

This time I am planning on drilling holes on the sides of the crack and injecting adhesive, then snuggling to the underlying lath with drywall screws and metal washers set in the crack.

Many posts state removing the screws after the glue has cured before applying your plaster. Is there a need to remove these screws? Or would it be more secure to leave them in? I understand I would have to sink them slightly and it may mean extra skim coats for smooth finishing. I want to prioritize long-term stability over a slight possible hump on the fault line after finishing.

 

[DGersic]

If you can sink them, I’d be tempted to leave them. I’ve had good luck with fibre tape on plaster crack repairs, but mine is on rock lath not wood like you have.

 

[P0234]

FWIW, there are a few Ask this Old House episodes on this very issue, might be able to find them on youtube. I think your plan is solid, leave the screws in, use fiber mesh, lots of it. Also make sure you address any movement, if the house is moving, nothing is going to stop it from cracking. Also I've had good luck with the 3M fiber re-inforced drywall filler, maybe a possibility here.

 

[tylerlongpt]

Great insight! Thanks to you both, I will use that compound. I'm wondering if I too have Rock Lath? How would I know?

 

[tylerlongpt]

Great insight! Thanks to you both, I will use that compound. I'm wondering if I too have Rock Lath? How would I know

 

[tylerlongpt]

Attempting to attach pictures

 

[jabin]

I have a 1920's plaster home, once the plaster pulls away from the lather it's very difficult to stop cracks, until that is addressed. There is a product that you can inject to reattach it. I've use to pulled it down, screw the wood lathes to the studs and re-plaster. I've had good success with the fiber tape also. Just beware, the plaster isn't smooth so any repair will stand out smooth vs Plaster texture if you aren't careful..

 

[four.cycle]

^ if it's old lath & plaster:

OPEN the crack with a CAN OPENER. (the punch-type with the pointed end.) Use it like a claw, pulling it toward you. Open up the crack so it's at least 1/2" wide (generally I'll go 5/8" - 3/4" width.)
WET the area down good. Use a spray bottle and wet the plaster along the crack.
Apply new plaster (or joint compound or "Fix-All") into the crack and work it in with a knife. Level it off to minimize required sanding.
WALK AWAY FOR TWO DAYS to let it dry.
Sand it down, apply texture as required. (Texture in a spray can is wonderful stuff - practice on a piece of cardboard first.)
Prime and paint.

 

[ycgoat]

When I had a 1920's built home I put 3/8" drywall over the plaster.

 

[jonesg]

look at the roof ridgeline, if its not straight check the foundation.
something is moving.

 

[egdede]

My house is 100 years old. I have a crooked Ridgeline but nothing is moving. 100k of foundation replacement later : ). But jonesg's point was that if you are having movement in your house your repair will soon fail. Without said, I screw my plaster down with these:

Amazon.com

I use a few of these to anchor large sections of plaster. You leave them, and they cover EZ (they are nicely convexed). I then use spray foam to glue that large section to the lathe. They were shipping a bad batch that had the holding dimples (around the screw dimple) punched the wrong way (they were opposite the screw dimple). This meant there was a 1/16 or so lip poking up through the mud. Even so, I could cover that without most people noticing.

 

[jabin]

https://plastermagic.com/

 

[75gmck25]

Your house is probably fine overall. Plaster is very inflexible, so any minor expansion or contraction of framing can lead to a crack. It it so hard that it can't give in any way other than to crack.

The repair techniques recommended above will work fine. One key point is to open up the crack enough (i.e., with the can opener blade) and wet it so the new plaster has something to bind to. If you want the fix to be more like plaster, then plaster of Paris is a good solution. However, drywall compound is more forgiving for drying time and sanding.

Rock lathe (looks a lot like drywall) was usually sold in 2x4 sheets, and it often has a standard pattern of holes to let the plaster seep through and help the plaster layers adhere. It's nailed to the joists, and then several plaster layers are applied on top. In my house the total thickness is about 1 1/8". If you have a place where you can see the back of the wall framing (crawlspace, plumbing access, etc.) you will see the back of the rock lathe.

 

[Pen & Wrench]

I have a 1932 home, and have done some research on repairing plaster cracks. I generally agree with everything above, except that from what I have seen, you have to re-attach the plaster to the lath, or the crack will simply re-appear. That being said, it appears to me the most successful and long lasting repairs are the ones where the crack was opened up sufficiently to remove the loose plaster, the adjacent plaster is re-glued or re-screwed to the lath, and then you will have a lasting repair. We found a guy, a friend of mine who had experience in re-texturing the plaster. Our plaster has a pimply look. First we re-plastered around the window I had rebuilt, and my friend took it from there, he got the texture to match up almost perfectly by using a pretty runny mud with fine sand mixed in and sprayed it on with a texture gun. If you don't know where to look, you can't tell where we made the repairs.

 

[Zeke]

The Plaster Magic looks gimmicky to me but I have never encountered it. The clamps or washers they sell do work and you can get them anywhere.



I too open the crack and use a Fit It All type of product. The previous version of that was called FixAll and it expanded some and didn't sand for ****. It was like concrete. Those that knew how to use it did fine. Then the product got sold to a tile grout company.

Also, there is a very fine mesh that you can cover the whole wall with if you have lots of spider web cracks. In the fiberglass industry they call it angel hair. I'm still looking for even a finer product, and there are a couple, but they are selling way over real market value.

Lots of people do that, take a common product and create a boutique market for it at inflated prices. You can go to a boat supply and buy angle hair by the yard.

And way back when, painters used something called sanitis cloth. It was embedded in primer just as the fiberglass. The fiberglass pattern will transfer though and has to be floated or textured.

 

[four.cycle]

"... a Fit It All type of product. The previous version of that was called FixAll ..."

the first time I ever used it (50+ years ago) it was "Fix-All".
LAST time I bought a box (last November) it was "Fix-it-All".
same product.
dries like CONCRETE. damn near impossible to sand. be sure to level it off when applying.

 

[KenC]

Good info so far. Many, many years ago I too had a plaster walled house. Probably built in the 30s, cracked and repaired more than once before I got it in the early 60s. Cleaned cracks out, repaired with setting compound, then covered the worst wall with cheesecloth bedded in setting compound. Troweled as flat as possible then a light texture. Lasted 10 years at least.

Today, I probably do the same but use fiberglass screen instead of cheesecloth.

 

[Zeke]

the first time I ever used it (50+ years ago) it was "Fix-All".
LAST time I bought a box (last November) it was "Fix-it-All".
same product.
dries like CONCRETE. damn near impossible to sand. be sure to level it off when applying.

Just a typo. Fix-It-All. Works well, it does actually sand better than the original. I mix it as stiff as possible and apply to, as previously mentioned, a wetted out brack opening and drag it off with a damp tile sponge. I try to leave it just a tad high. If it shrinks I apply regular spackle or mud over the repair and feather that out.

 

[four.cycle]

^ To patch dings and dents in painted cabinet work (particularly drawer and cupboard fronts), mix the "Fix-All" (or "Fix-it-All") with MARINE SPAR VARNISH (instead of water).
You can only make small batches. Work quickly. Knife it off level it's not going to shrink much and it is like sanding concrete after hardening. If applied properly (to PRIMED surfaces) it will NOT fall out of those little bumps and dings you're wanting to hide.
Takes a day or two to dry.

 

[Zeke]

^^^In that case I'm using bondo.

 

[four.cycle]

^ yeah... about the same, really. I've used it on old dressers and cabinets on drawers and doors that take more than their fair share of abuse. sanding is definitely challenging.

 

[tylerlongpt]

FWIW, there are a few Ask this Old House episodes on this very issue, might be able to find them on youtube. I think your plan is solid, leave the screws in, use fiber mesh, lots of it. Also make sure you address any movement, if the house is moving, nothing is going to stop it from cracking. Also I've had good luck with the 3M fiber re-inforced drywall filler, maybe a possibility here.

I purchased the 3M Fiber filler- would you recommend using this over mesh tape or without mesh tape?

 

[P0234]

I purchased the 3M Fiber filler- would you recommend using this over mesh tape or without mesh tape?

I'd use both, the tape is going to be the part that really holds it together.