thanks in advance for your thoughts.

I recently purchased a 1920s house that suffered water damage to a third floor (attic conversion) bedroom. The slate roof has been repaired--the chimney is on the damaged wall and the flashing was replaced--and I now want to get started on repairing the wall/ceiling water damage, particularly so I can know for certain if the roof repair was successful.

I have a Klein Pinless Moisture Meter that shows the wall is still wet--I put it on the drywall setting even though the walls are plaster (to my knowledge) since that's the closest match. Since it's been a week since the last rain/roof repair, I decided to cut out an area to see what's going on. (Note: The exterior walls that I have drilled into thus in other places far have been plaster on brick. I haven't had a chance to see how the interior walls look but I believe it's the usual old style lathe/plaster).

Before I go any further, I figured it's best to post on here to get some expert opinions. Note that the left side of the wall is an exterior wall and the right side that I've cut into has the chimney on the other side so it should also be plaster on brick. Any thoughts on the situation and next steps? Keep cutting or call in a pro? Is mold a valid concern?

Photos: https://ibb.co/album/v1TY0w

  • 3
    1920s will need to be aware of the possibly of lead paint and asbestos in building materials. Lead is a concern if young children are around(no dumping just in the back yard). Asbestos will need a mask at least. Both need tests to prove they there or not. Moisture needs the air to move to dry out, inside of a wall is just like a bottle/container with the cap/lid on.
    – crip659
    Aug 16, 2022 at 22:05
  • So you suggest that I keep cutting some holes to let it breathe, right? Would you JC/mud it after that?
    – Aaron
    Aug 16, 2022 at 22:11
  • 1
    Holes will help to dry it out, but be aware of the lead paint and asbestos that might be there. A decent mask should be enough to protect you. The room should be sealed to prevent dust going everywhere in the house. Small fans will help also.
    – crip659
    Aug 16, 2022 at 22:29
  • There's no lead but I haven't had a chance to test for asbestos yet, though I've read it's not common in 1920s houses (that said, I can't confirm if this wall is original). What would be the next step after drying?
    – Aaron
    Aug 17, 2022 at 19:56
  • Next step is to see how bad(soft,loose) the plaster is, and repair/replace as needed..
    – crip659
    Aug 17, 2022 at 20:02

1 Answer 1


Taking appropriate precautions re lead/asbestos, get rid of all the existing plaster that you're going to replace eventually.
That will be a few tons less material to dry out. You'll also not be trying to evaporate it through the paint & artex, both of which are somewhat impervious to water.

  • Keeping in mind my goal of minimal replacement, how much removal would be suggested? I was initially thinking I would wait for the area to dry then scrape off the damage (bubbling/raised parts) and joint compound/mud, prime, and paint. Is scraping off the damage, waiting for it to dry (may take a while if I don't go deep), and then JC/mud/paint a viable course of action? Or do I have to get rid of all plaster that has gotten wet? I've never dealt with plaster before so I don't know if it's usable after it's wet then dried. Also, is mold a factor if it's just brick and old plaster?
    – Aaron
    Aug 17, 2022 at 20:01
  • You have to take off whatever's not still firmly stuck to the wall - that's something you find out as you start to remove it. Be prepared that on a house of that age, most of it might already be loose, damp or no damp.
    – Tetsujin
    Aug 18, 2022 at 7:52
  • @Aaron: "I was initially thinking I would wait for the area to dry then scrape off the damage". Instead, get rid of the damaged stuff now, that will speed the drying of the rest of it by allowing airflow all around. The damaged stuff will have to come off anyway, so may as well save yourself some time.
    – FreeMan
    Aug 18, 2022 at 14:08
  • Fair enough, I will do the removal of at least the bubbled up parts now. Is this a situation where I can use joint compound/mud to fill in the removed areas or do I need to have it replastered?
    – Aaron
    Aug 19, 2022 at 19:44

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