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  1. #1
    Join Date
    Jan 2008
    Posts
    10

    Default fixing cracked plaster ceilings

    I have large cracks all over my upstairs ceiling, which are plaster, I've heard of drilling holes & gluing it back to the lathe, does any body know what to use or where to get these products, or have any better ideas to fix this problem? Any help would be greatly appreciated.

  2. #2

    Default Re: fixing cracked plaster ceilings

    The product you are looking for was demonstrated on Ask This Old House show #603, the web site is www.plastermagic.com

  3. #3
    Join Date
    Dec 2007
    Location
    Corvallis, Oregon USA
    Posts
    37

    Default Re: fixing cracked plaster ceilings

    If the plaster is only cracked and not sagging, you can clean each crack of any loose material, then treat each one like a drywall seam. Use joint mud to glue down the paper tape, then skim coat the ceiling. It will probably take at least two and probably three coats. A big job, especially if you haven't done it before.

    Another approach I have used is to overlay the ceiling with 3/8 drywall. Use 1 5/8 inch drywall screws, go for the joists and where you can't find them, screw into the lath. (You will have to probe and measure to locate the joists.) You can also put some adhesive on back of each sheet for extra insurance.

    With drywall, you have a permanent fix. I do lots of this. Of course, the big thing is to do a good job finishing and texturing the drywall. But done well, it makes a nice solution to ugly old ceilings. Good luck.

  4. #4

    Default Re: fixing cracked plaster ceilings

    If you rake out the crack in the plaster and its pre-1930 you will weaken the plaster by ripping the fibrous binder. Putting paper tape and joint compound on plaster cracks is like painting a water stain on your ceiling to fix a roof leak. Paper tape is superficial reinforcement for the crack and what is needed is fundamental stabilization. Plaster repair is all about stabilizing your plaster, not layering more material on top. Once the wall (or ceiling plaster) is stable the rest is cosmetic. Laminating sheetrock on top of plaster is taking the quality of your surface down a notch besides usually being completely unnecessary. I have yet to see a sheetrock taping job last five years before the seams show up again. The permanent fix it to use adhesive stabilization using the lath behind the plaster the bridge the crack. After the plaster is stabilized the rest of the repair is cosmetic.

  5. #5
    Join Date
    Dec 2007
    Location
    Corvallis, Oregon USA
    Posts
    37

    Default Re: fixing cracked plaster ceilings

    Just some further comments on dealing with badly cracked plaster ceilings.

    While I recommend cleaning the bad cracks as a first step, I am not talking about raking them out down to the lath. That is foolish and unnecessary. Just some gentle pressure or scraping with the edge of a taping knife or some such tool to remove ridged or loose paint.

    If the plaster is sagged in some places, then stabilization of some sort needs to be done. One way is as already suggested - drilling small holes into the sagging plaster and injecting glue into the holes then re-attaching the plaster tight against the wood lath with special screws until the glue dries. You are still left with a cosmetic problem of cracks and holes to hide.

    Another way is to remove the sagging plaster entirely and fill in the gap with thin drywall glued and screwed into place. Fill in around the edges of the patch with hot mud, then apply paper drywall tape over the edges to tie the patch securely into the surrounding plaster. Then tape the rest of the cracks in the ceiling and skim coat the whole thing.

    This may be more labor intensive than most people want to do, but it is a permanent fix for sagging plaster when it only occurs in spots here and there in a ceiling.

    If you are planning to overlay the whole ceiling with thin drywall, then you can first nail furring strips over the joists where they are exposed after the sagging plaster is removed. Then go ahead and put up the drywall.

    It is true that drywall seams can show if they are not done well. However, I have hung and finished drywall over really bad plaster ceilings for over 35 years, and I have yet to have a single callback because the seams showed up later. So it depends on your skill level, whether the drywall option is one you want to consider. You could always hire a professional to do the finish work after you install the drywall overlay.

    The advantage of a well-finished drywalled ceiling is that the plaster underneath can never again be a cause for concern. But, with taping the cracks and then skimcoating, there is always the risk that vibration caused by upstairs foot traffic, sonic booms, earthquakes - you name it - can cause new cracks to form where they didn't exist before.

    For me and my clients, the drywall option is usually the quickest and least expensive way to go. And I can finish it so you would never know it is not plaster. So, really, there are lots of factors to consider in how you approach an old damaged plaster ceiling. There are NO simple solutions, just do-able ones.

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