How do I repair wet plaster?


this Is plaster covering a brick fireplace. Behind some of these areas the plaster is soft and indents when you push on it. No roof source of water entry have been found. How do I repair the wet plaster as it has not hardened overtime and I am concered for mold

q how do i repair wet plaster
  13 answers
  • Oliva Oliva on Jul 24, 2020

    What is the relative humidity in this room/area? Have you tried running a dehumidifier? The chimney may need repointing, or you may have cracks in the crown area of the chimney, which will require a mason's expertise for repair/rebuilding. The chimney may have damage in an area you yourself cannot see. A chimney repair company will have access to a camera, for this purpose.

  • Dee Dee on Jul 25, 2020

    It may be that the plaster was mixed with too much water. You may have to remove the plaster with a scraper or by sanding and red0 the wall.

  • Redcatcec Redcatcec on Jul 25, 2020

    Looks like water is seeping in somewhere above the puffy areas, is it worse after rain? I would scrape off the affected area removing any wet plaster and see if there is any wetness above it or mold starting. If not let it dry thoroughly and re-plaster. If there is you may need to call in a professional.

    There might be some hairline cracks in the chimney (assuming this is brick and mortar) or the flashing is beginning to leak.

  • There must be water coming in from somewhere. Plaster will dry over time. Unless it is just soft because it is powdery from not being mixed properly.

  • Robyn Garner Robyn Garner on Jul 25, 2020

    Yes, water MUST be coming from somewhere!

  • Nan W. Nan W. on Jul 25, 2020

    The water IS coming from somewhere!! Scrape off the plaster and have a good look!

  • Oliva Oliva on Jul 25, 2020

    Your water infiltration is most likely due to cracks in chimney mortar, flashing, or the cement "cap". Due to the length of the chimney, you may find damage far above your indoor sightline. When was the last time this chimney was professionally inspected?

  • I would remove that plaster and see what is behind it. It wouldn't just stay moist like that for no reason. Better to check it out sooner than later so you don't get mold.

  • Agnes Chrzanowska Agnes Chrzanowska on Jul 25, 2020

    I would not try to repair ...There is most likely issue that is why it is wet. Open up that area and see what needs to be repaired there before

  • Ken Erickson Ken Erickson on Jul 25, 2020

    Remove it to see if there is a water source. Plaster and sheetrock mud should always be put on in thin coats so it can dry properly. I have tried to put too much mud or caulking into a gap before.

  • Kmdreamer Kmdreamer on Jul 25, 2020

    You should be able to sand down and patch it with plaster don’t push to hard it sounds like it’s hollow underneath.then paint it

  • Betsy Betsy on Jul 29, 2020

    Hi Kelly: Mix up a small batch of setting-type joint compound and use it to fill the crack and all the holes. Smooth the wet compound with a trowel; then, as it begins to harden, wet it and smooth it again. After the compound sets, sand the area lightly, then prime and paint. Good luck