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Old-House Online » Old-House Tips, Restoration Stories, & More » Repairs & How To » Ceiling Repair » How to Fix Plaster Ceilings

How to Fix Plaster Ceilings

Techniques for reattaching plaster ceilings and easy tips for plaster ceiling repair.
Story and photos by Peter & Noelle Lord

    Delaminating plaster ceiling

    Stained cracks and suspicious shadows—the telltale signs of a delaminating plaster ceiling.

    What old-house owner doesn’t have a cracking or sagging plaster ceiling in need of repair somewhere? Besides the normal wear and tear of living, plaster-and-lath ceilings are at the mercy of gravity, and they can take only so many water leaks and structural movements before they pull away from the framing. The good news is, it’s possible to repair and rescue them from further damage. We have successfully reattached many old ceilings by injecting adhesive between the plaster and lath where the keys (anchors) have broken away over time. Though variations of this technique are not new texts from the 1920s recommend liquid sulfur as an adhesive-we use modern materials that are easy to handle and inflict minimal damage to sound plaster. With these methods and good tool skills it’s possible to restore the integrity of plaster ceilings for many more years of service.

    Sizing up the Ceiling

    After correcting whatever problem made the ceiling loose in the first place (leaky roof, structural alterations), the first step is to assess how far the ceiling has pulled away. Gently push on the surface and judge the amount of play between plaster and lath. Hopefully, you will feel it move back into place like a jigsaw puzzle piece sliding into its own unique spot. If there are broken keys or debris in the way (see sidebar p. 54), the plaster will resist seating, and it will feel and sound “crunchy” akin to breaking eggshells or crushing popcorn. Do not force it back into place or more plaster may break. Instead, just gently encourage the plaster with the flat of your hand. If the separation is slight—say, between 1/4″ and 1/2″—good reattachment is likely because the plaster will usually push back into place solid and flat against the lath. If the plaster sags 1/2″ to 1″ from the lath, there is often too much debris (broken keys, years of silt) between the plaster and lath for success.

    Clearing injection holes with vacuum nozzle

    Holding a vacuum nozzle on the drill bit helps suck the 1/4" injection holes clear of dust.

    Unless you can vacuum out all this debris from above, reattachment is probably not an option. Often we find that the worst part of the ceiling has too much debris, and we have to remove this section, reattach the edges, then infill the lost parts with new plaster. Plaster that is soft and crumbly will not hold up during the pushing and drilling and has to be removed as well. Removing areas of damaged plaster—particularly in a ceiling—will encourage more plaster to come down, especially if you use a chisel-edged tool. (We call this the domino-delamination effect.) To control this tendency we recommend carefully marking out your repair plan, then removing any areas with a sharp utility knife. Mark with a lumber crayon or pencil; a pen will bleed through your paint later on.

    The holes you bore to inject the adhesive must be directly beneath the wood lath—not the spaces between the lath—so that the adhesive can bond to something solid. If you have removed any plaster, or dug out a crack for repair, then you can see the positions of the lath. In a reattachment-only repair, however, finding lath is basically hunt-and-peck. Sometimes, if the plaster is not too thick, you can stand back and look for ghosts or shadows of the lath showing through the finish coat.

    Once you have a solid fix on one lath, assume that the rest of the lathing is 1 1/2″ to 2″ wide and spaced approximately 1/4″ to 1/2″ apart. If you have an infill area that needs reattachment at its edges, mark for injection sites 1 1/2″ to 2″ back from the edges. If you are only reattaching plaster, plan for injection holes every 3″ to 4″, no more than 6″ apart.

    Adhesive sealing of plaster ceiling

    The 1/4" injection hole is an effective size for a good seal with the adhesive tube.

    We bore injection holes with a 1/4″ carbide drill bit. Making these holes presents a second challenge because it is very important to bore only through the injection surface. For example, if you are reattaching from the plaster side, you must bore completely through the plaster, yet stop before going into the wood lath. Conversely, if you are reattaching from above, you need to bore through the lath, but stop before the plaster. By paying attention to the changing resistance of the materials on the drill bit, it’s possible to develop a feel for these different layers. After you have bored your injection holes, you need to vacuum out the debris and drilling dust. Older plaster is soft, so be careful not to suck it off the ceiling with the vacuum! Place your hand near the hole to gently support the plaster while you vacuum using the other hand. Do not push the plaster back up into place, however; the void will allow the vacuum to pull some of the debris out through the hole.

    If you have access from above, you can vacuum more of the silt and debris. Remove keys that are visibly loose or broken as well. Use a wet/dry shop vacuum designed to handle the fine dust. Plaster will kill a household vacuum in short order. Next, wet the injection holes by either spraying down the lath with a squirt bottle or squirting up into the drilled holes from the plaster surface. Wetting encourages the adhesive to travel farther when it is compressed and will also slow the drying time slightly for a stronger bond.

    Bonding and Shoring

    Finally it’s time to inject adhesive. We use a water-based, latex product that is actually a vinyl floor adhesive. However, any good-quality latex or acrylic adhesive can work (for example, Liquid Nails or floor adhesive). You can purchase these products at construction supply houses and hardware stores in caulking tubes for small projects or five-gallon pails for large jobs. We use a caulking gun with the tip cut to fit snugly in our 1/4″ holes, and inject the adhesive until the plaster moves ever so slightly (one squeeze of the average caulking gun is usually enough). If you inject too much adhesive you will actually push the plaster off the ceiling. As you inject, follow along with a damp sponge to wipe away the excess adhesive that leaves the holes when you remove the nozzle.

    Wire lath

    Adding wire lath over wood lath improves an infill repair.

    Complete your entire series of holes, then go back over the plaster with a clean, damp sponge to remove further glue residue. Follow the same process if you’re working on the lath side, leaving adhesive wipe-up as an optional step. Once we have injected adhesive into the repair area, we push the plaster back into place against the lath and secure it with forms. This step spreads the adhesive so that it bonds to a greater surface area. We use flexible plywood squares (1/2″ to 3/8″ thick) covered with a layer of sheet polyethylene. Do not underestimate the importance of this layer of poly; if you forget it you will glue the plywood to the ceiling and take all the plaster with it if you attempt to remove the form. (Sound like first-hand experience?) Last, we secure these in place with screws or wood shores running to the floor, then allow the adhesive to set up for 24 hours.

    Screws save the time of fitting wooden shores and keep the work area clear, but they can damage the plaster and leave more holes to fill later. Shores are more appropriate for fragile, decorative, or museum-quality plaster, and we use them for both plaster-side and lath-side reattachment. The next day you can remove the forms. Where some of the plastic sticks to adhesive injected from the plaster side, simply scrape it off with a putty knife. The adhesive is still soft around the holes at this point, but has set up enough to remove the forms. On the plaster side, scrape off the dried adhesive residue with a drywall or putty knife, then use the corner of a putty knife to gently scallop out excess adhesive showing from the hole.

    Restored plaster ceiling

    As with all good restorations, a successful repair is hard to see.

    As it dries fully over another day or so (depending on heat and humidity) the adhesive will further retreat into the hole, leaving a clear space to fill. We usually fill the injection and screw holes with Durabond 45 (sandable), mixed to the consistency of peanut butter, because this product has a quick set-up time and dries very hard with minimal shrinkage. However, any vinyl paste filler or plaster/joint compound can be used for this step. Usually, it takes two to three applications to fill the holes flush with the ceiling, depending upon the product. Other than this, the ceiling is now reattached and ready for a skim-coat of plaster or a fresh coat of paint.

    Peter and Noelle Lord, operators of Peter Lord Plaster & Paint, Inc., specialize in the preservation and restoration of historic surfaces and all plaster systems.

    Published in: Old-House Journal January/February 2001


    Bruce Davis May 3, 2012 at 9:58 pm

    My house was in 1896. Story and half brick. It has suffered thrum 32 years neglect. Dry was nailed over the plaster to cover large cracks. Pulling the drywall off results large sections of plaster coming with it. We also have asbestos textured paint in 3 rooms. Any suggestions as to how I save the plaster? Also the plaster literally falls off the brick walls. Thanks

    Amy Douvlos June 18, 2012 at 6:56 pm

    Check out Big Walley’s plaster repair kits. Use a spray and wash nozzle for the conditioner so you don’t waste it. It is tapered and will fit inside the holes. Don’t forget the drop cloth!

    kari dunn November 7, 2012 at 3:50 pm

    Hi, our plaster walls are ‘finished’ with a heavy paper. It is not decorative. There is a term for this sort of plaster finish, is anyone familiar with it? Is it something I can repair?

    noel June 10, 2013 at 10:28 pm

    I live in a 20 year old condo and just moved in here 2 months ago and I looked at the ceiling in the kitchen abnd there was a very big crack in the ceiling and was told by property manager that this is my fault and I am suppose to look after it and it was caused by a plaster blow with the building shifting

    Angie aka Mom the Builder August 23, 2013 at 10:17 am

    After repairing my plaster and noticing the cracks reappear every change of season, I decided to cover my plaster ceilings with beadboard and faux moulding trim. The result was amazing and I get tons of compliments. I posted step by step directions for free on my blog:

    Hopefully this helps some of you!


    Sherrie September 6, 2014 at 1:55 pm

    My house has a crack in the ceiling and it looks like a cement board with plaster on top. Is that possible and how would I repair it?

    Tejas Solanki October 27, 2014 at 12:36 pm

    Our house ceiling is braking as the iron rods that were holding the cement are corroded. Can anyone please suggest what can be the cheapest way of repairing it and what can be the best thing to do. cause we cannot put cement again as it does not have the grip to hold it. House is 100 years old but the walls are very strong but only problem is the ceiling. Can anyone suggest??

    Dan January 16, 2015 at 6:05 pm

    I’ve read articles describing 2 types of anchoring rings. One is plastic and the other is metal.
    Where do you think that I can purchase the plastic rings (the big box stores don’t carry them) ?

    GAIL JACK January 17, 2015 at 4:25 pm



    Ernest Quist February 4, 2015 at 12:33 pm

    I have a lot of little flakes coming from my ceiling in the kitchen and dining rooms. Ceiling has the rough looking plaster. Is there any way to stop these flakes from falling? Thanks

    Sue Green February 26, 2015 at 4:21 pm

    The ceiling plaster has gapped and crumbled away from what looks like a cement board.How would I repair it? Thank You in advance for your help.

    Sammy March 30, 2015 at 12:33 pm

    I tried both glue and plaster washers/screws on ceiling and walls. so far the best method was using plaster washers.. I am going to try next counter sink the washers to minimize patch work.

    Jordan Jorgenson October 21, 2015 at 1:00 pm

    I liked your idea of holding a vacuum next to the drill while preparing the damaged area for plastering. In my opinion the worst part of any construction/remodeling project is the cleanup. So, anything that I can do to minimize cleanup is welcome. Thanks.

    richard vanderbrug November 8, 2015 at 6:27 pm

    I live in a condominium built to 1967. The bathroom ceilings are plaster against concrete block (no lathe). Where there are large valleys (an inch or more deep), can I just plaster over then in successive coats?

    emily bennette February 23, 2016 at 10:41 pm

    Having a cracked ceiling is pretty scary for a homeowner. You never want to have to worry about if it is going to cave in on you. I had no idea that you needed to do some much to it so the plaster will stick to the ceiling. It seems like you should get it fixed as soon as possible sounds like the best thing you can do.

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