We have a wall with some long cracks. Simple spackling doesn’t help; the cracks come back in days. At first I figured that some taping was needed, but then I thumped along the wall and heard differences.
I’m guessing there used to be a passageway that was later closed off. So, what appears to be one solid plaster wall is actually a plaster section extended with drywall. Most (although not all) of the cracks are along the transition from plaster to drywall.
What is the best way to fix cracks between different substrates?
Janet
Replies
just a bump to move this along. I do a lot of sheetrock repairs but have never had to join rock and plaster. You're at the right place for an answer and I'll keep watching for a reply to learn how to join these.
Never fear the want of business. A man who qualifies himself well for his calling, never fails of employment.
Thomas Jefferson
3rd president of US (1743 - 1826)
There is a type of fabric that you can apply over the wall in a similiar fashion to wall paper then you can skim coat over it.
I have no idea of what it is called generically or by brand.
"When the spirits are low, when the day appears dark, when work becomes monotonous, when hope hardly seems worth having, just mount a bicycle and go out for a spin down the road, without thought on anything but the ride you are taking." — Sherlock Holmes, 1896
Or, I could use paper tape or mesh tape. But will that prevent cracking?
I would open the cracks up a little with a can opener or the corner of a scraper.
Prefill with hot mud. Tape with hot mud and paper tape and coat as needed.
If there is structural movement, that must be addressed first or else it will reoccur.
I have done lots of sheetrock/ plaster patches, not really the right thing to do but it works if done soundly.
Mike
Small wheel turn by the fire and rod, big wheel turn by the grace of god.
When I was in business we did a fair amount of this. We scraped out any loose plaster/mud debri. Then carefully shot some screws directly on either side of the crack to make sure the material was solidly fastened to the lathe. Bump the screws in as it will split the lathe easily. Also on the plaster areas counter sinking the heads using a 3/8 drill bit will help.
Then using hot mud and mesh tape (I know no one likes it but in this case we simply had more success with it) finish the cracks in the usual fashion. Last two coats we used bucket mud.
If the cracks are wide or you have multiple cracks in a small area you can get on line and buy mesh tape in different widths up to a 24" wide. We kept a couple of rolls of 6" around the shop for the occasional situation such as described. Hope it helps! DanT
Like others have said, hot mud and tape. When patching cracks in plaster (or between plaster and drywall), open up the crack enough so the patching material can get a good grip on the lath underneath.
Here's a tip -- I've never seen anyone do this but me, but it seems to work pretty well. When mixing the hot mud, use thinset admix instead of water, or at least instead of part of the water. This makes the mud stickier and lets it move a bit after setting. It will take overnight to dry tho', and you can't smooth it out like you could regular mud -- too sticky -- so you'll need at least one topcoat. Makes one heck of a patch tho'.
Mike Hennessy
Pittsburgh, PA
Everything fits, until you put glue on it.