My apartment was built in 1910 and has plaster walls throughout. The wall that separates my unit with that of the neighbor has plaster over brick.

After 100 years the plaster started separating from the brick wall and came loose. I decided to remove the loose plaster and re-plaster the wall using a structo-lite base coat. I applied plaster weld bonding agent than a base coat layer / scratch coat.

I woke up this morning and I realized the base coat has cracks all over it! See photos below.

wall after removing loose plaster

enter image description here


I guess at this point I was planning to apply a brown second coat but with all the cracks on the base coat, I'm not really sure what to do here.

Any tips recommendations would be greatly appreciated!

  • After a 100 years plaster becoming unstuck might have other problems, especially inside. Might need to find those problems before plastering again.
    – crip659
    Mar 15, 2023 at 23:42
  • Have you noticed any humidity problems
    – Traveler
    Mar 16, 2023 at 0:09
  • The original mortar was a wrong mixture and dried to fast, creating cracks leading to failure
    – Traveler
    Mar 16, 2023 at 0:12
  • Here, we have many houses that were built back in the days of case-hardened bricks and lime mortar, and I've been told that it's important that the mortar be able to transpire so sealing it with anything less porous than plaster would be questionable. (My house dates back at least to the 1890's, and I have horsehair plaster surviving over some but not all of the brick-over-fieldstone foundation.)
    – keshlam
    Mar 16, 2023 at 3:53
  • Perhaps your scratch coat was too wet, causing shrinkage and cracking?
    – Huesmann
    Mar 16, 2023 at 13:19

1 Answer 1


Simple answer: YES Let the base you put up dry for several days. Then finish the wall. Just be sure to actually mix the correct amounts or you'll have the same issue again.


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