How To Repair Old Plaster

One of the easiest mistakes to make when renovating a historic home is to tear down the old plaster walls and replace them with modern drywall and joint compound. This not only destroys the historic architecture and features that make a historic home great, but it also adds to the overall costs of the project exponentially. Lime plaster has been in use for thousands of years from Japan to Egypt and has been employed in many historic structures around the globe. Lime plaster is a far superior product than today’s modern wall coverings. With its crystalline structure, it repels moisture well while allowing for contraction and expansion that often occurs in older homes during changing weather conditions. In fact, as the plasters structure calcifies (ages), it increases in durability and strength!

A Little History First

Traditional lime plaster was used for wall coverings until WWII. It was applied in a 3 coat process over thin wood furring strips called lath that were made of cedar, cypress or some other rot resistant non-staining wood and attached to the studs. The lath was soaked in water prior to installing the plaster to prevent it from sucking too much water out of the the plaster too quickly and spaced similar to the above picture with room between each piece for plaster to be pushed thru when applied. This spacing allowed the plaster to “key” in the lath and gave it extraordinary holding power when done properly.

The plaster was then applied in successive coats, typically 2, and a smooth finish coat was applied on top. Plaster took weeks to dry properly and fully cure before the walls could be painted. The whole process was slow and required a skilled plasterer which cost more money. After WWII the building industry needed a faster way to cover walls and the relatively new product, drywall (getting its name from the fact that it didn’t go up wet like plaster), slowly crept into everyday use.

The Repair

  1. Assesing – There are many reasons for lime plaster to fall into disrepair. Knowing the cause of the damage is crucial to applying the correct solution to the problem. From water damage to vibrations from nearby traffic to peeling paint, historical plaster damage can be caused by many problems. Is the plaster peeling from the lathe? Is the plaster soggy or crumbly? Are new coats of paint peeling from the walls? If you answered yes to any of these questions; don’t panic. While each condition is unique to each situation, lime plaster can be repaired easily, economically and effectively. A common occurrence in older plaster, cracks are commonly caused by expansion and contraction of an exterior wall. In the case of heavy cracking, it is possible to that the house it settling improperly. This should be inspected by a Building contractor or structural engineer immediately! Repairing smalls cracks is the focus of this writing though.
  2. Dealing With Cracks – This repair can be done by drilling several small pilot holes in the materials at various intervals. By measuring the depth of the penetration, you can determine if the lathe is detached. Many times a few well-placed screws can draw the lathe and plaster back together. In extreme cases of detached lathe, more holes are drilled into the affected area and an elastomeric adhesive is injected between the separations. Clamping washers are then applied to the surface of the plaster to press the loose plaster back tightly against the lathe and allowed to dry. Once the plaster is secured, the holes and cracks can be filled flush with a mixture of lime and gypsum, allowed to dry and then painted. Check out my video on fixing cracked plaster to learn how to do it yourself!
  3. Peeling Paint – Another common dilemma when dealing with older homes, peeling paint can be repaired with just a few simple techniques. More often than not, peeling paint occurs when many layers of paint have been applied to the plaster over the years. Calcimine is the common culprit of many peeling paint plaster problems. Calcimine is a water soluble paint material that was typically used in older paint products. The calcium in the paint reacts with the moisture content of the calcium in the lime plaster and creates a bond between the water molecules. This bond easily allows water to slip in and out of the paints surface, so even if you apply new paint, it peels over time. To remedy this problem, the old paint must be removed. A wallpaper steamer is the perfect tool for removing old paint from lime plaster. Gently use the steamer and a plaster knife to remove the paint without gouging the plaster. Once you’ve removed all of the old paint, wash the plaster with a rag and room temperature water. Don’t get the walls too wet; a light wipe down will suffice. Allow the plaster to dry 24 hours before repainting.
  4. Patching – Patching plaster in anything more than small amounts is something best left for the pros, but if you are a brave DIYer then you can try to tackle the task on your own. Old plaster is made from much different materials than current drywall joint compound. You’ll need a good gauging plaster mixed to the consistency of creamy peanut butter split 50/50 with lime. Once your plaster is mixed apply it with a putty knife and press it firmly into the supporting lathe. Make sure the plaster isn’t sagging in the hole. If so your mix is too watery and you should add more plaster and lime until it is firm enough to hold under its own weight. Once the plaster has dried give it a light sanding to smooth out the surface and wipe it down with a damp rag before painting.

While some damages can be easily repaired, it’s easy to quickly get in over your head when it comes to plaster repairs in a historic structure. Plaster work is an art form and many delicate cornices, crown molding and ceiling medallions were sculpted by hand by skilled craftsmen. So before you rip that old plaster down to insulate and cover with drywall think twice. You might have a unknown work of art on the walls or ceiling of your home that deserves restoring.

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by Scott Sidler

I'm a historic preservationist and licensed contractor. I help old house lovers understand & restore their homes so they can enjoy the history and character that surrounds them more everyday! When not working, writing or teaching about old houses I spend most of my time fixing up my own 1929 bungalow with my wife Delores and sons Charley and Jude.

http://www.AustinHomeRestorations.com

65 comments

  1. Scott on said:

    I have an old 1920s mortar bathroom. I excavated an opening for a shower niche, then repaired the area around the box with Plaster of Paris. Then Redgard (2 coats) over that, then tile. Was this ill-advised? I know gauge plaster isn’t rated for wet areas, but the area behind the wall has a vent and good circulation. So far everything is holding up.

    • Gypsum plaster is not a good idea in wet areas. You may have trouble in the future but the redgard will definitely help. I would have used modified thinset for the niche and then redgarded that.

  2. Allen on said:

    I need to smooth out plaster/lathe ceiling and walls and some cracks and holes. I know now to use spackling. I don’t know what is the best product to use. Can you advise? Also, I read about Gardz primer as being a good primer for plaster. Anyone have experience with this? Any input appreciated

    • For small cracks sparkle works well, but to skim coat a whole wall you’ll need veneer plaster. I like a good latex primer for cured bare plaster or spackle.

      • Allen on said:

        Thank you Scott for your input. I have read that plaster patch for holes and pressure cracks works best. Are you familiar with that? Do you know kanything about/ or have experience with Zinnser Gardz?

        • Haven’t used Zinnser Gardz, but I do like their other products. Usually for cracks we dig out the hole a big more and then fill with spackle if we aren’t skim coating the wall. Or we filled with a mixture of veneer plaster and joint compound if we plan to skim coat the wall.

  3. John White on said:

    We live in a 1926 house all plaster ceilings and walls. The fireplace is also plaster with brick underneath. We had a small earthquake about 10 years ago. Since the earthquake where the fireplace meets the floor about every 8 months or so small bubble like protrusions develop and some flaking, we have been just sanding and repainting. We were told this was caused from the bricks that shifted during the earthquake letting water leak in but we have always had a chimney cap. Is this something we should be worried about or just keep sanding and repainting?

    • Heart on said:

      Hi John,
      Congratulations on owning a beautiful plaster home. Suggestion: check where your roof meets the fireplace. I suspect the earthquake may have created a gap where water is seeping in. Try resealing the roof to the fireplace & see if this helps. Let us know…

  4. maralee foster on said:

    Thank you for writing this article, I have learned much from it.
    I am considering purchasing a home built in the late 1800’s to early 1900’s. It has lath and plaster walls. The thing that bothers me is that though painted nicely, for some reason the walls have the appearance of having been painted hundreds of times. I am wondering if this is because the plaster appears to be textured on the walls. I am wondering if this is the way that plaster walls always look or if this was a technique used on them. Do you have any suggestions for giving the walls a fresher look? Thanks for your thoughts.

    • Maralee, likely they are textured walls (likely a sand or perlite texture) that has been painted multiple times. They can be skim coated with a smooth coat of veneer plaster if you want to change the look.

  5. Bev on said:

    In the oldest section of our historic home, the stucco was removed from an exterior wall and the stone was pointed. Inside that wall, between the corner of the inside room (the kitchen) and the outside door, the plaster has shed it’s paint and the top layer of the plaster has turned to powder, constantly shedding plaster powder. Several people have tried to repair the plaster inside and to waterproof the outside with no luck. Any ideas?

  6. Gene Myrick on said:

    Just cover the entire wall with sheetrock and paint the sheetrock.

  7. Caity on said:

    My husband and I are moving into a 1870s (?) farm house in Allenwood NJ. The plaster is in rough shape and we are hoping to have someone come and do repairs to it. Do you have any recommendations on how to find a plasterer? We are having a hard time finding one. Thank you!

    • Heart on said:

      Hello Caity,
      Thank you for Restoring your farm house in Allenwood, NJ.
      When looking for someone who can restore plaster, I would start with the local Historic Preservation Society. They may have leads for you to either find local plasterers or other local home owners who have restored their homes. You could also try the plasterers & cement masons union in your area. Talk to retired contractors in your area as well. Make sure to exchange contact info as they are a wealth of information in restoring old homes. Don’t give up, you will love living with your restored plaster walls. Hope this helps.

  8. Liz on said:

    We have a house built in 1950 that has plaster walls, and I assume the ceilings are as well. We love the plaster walls! It’s SO quiet. There are a few cracks here and there on the walls, but they are generally in good shape. The living room ceiling, however has cracks all along the joists. It’s obvious that many repairs have been done over the years. The weird thing is, there are some simple linear cracks, but also, so of the cracks appear to have bulged out and have been sanded down in the past, and some are still bulging.

    There was a crazy cat lady who lived here before us who let the cats go in the attic and relieve themselves! We had to have all the insulation removed and replaced, and they sprayed a sealant on before they put in the new cellulose.

    So that could be the source of the weirdness, but it should also be fixed now.

    What should we do about the cracks in the ceiling? Are they indicative of anything the we need to address? do you have any videos or sources on fixing ceilings?

    • Heart on said:

      Glad you appreciate your plaster walls as much as we do Liz. They truly are remarkable for their durability, craftsmanship & insulation properties.

      Regarding living room ceiling: It’s possible that there was still ‘moisture’ in the plaster when they sealed the attic. The lumps may be caused by the moisture trying to escape downwards. If the ceiling has coats of wallpaper or paint the moisture might be swelling in the plaster. Since we suspect the problem is cat urine not water, I would (in this case) tear out the whole ceiling. You could either have it re-plastered by a professional ($$$) or replace the whole ceiling with drywall ($$). This will remove all the problems at once.

      One suggestion (albeit not the best) would be to sand the lumps in the plaster flat & allow it to ‘breath’ (it won’t smell pretty), allow it to dry out over the summer. Use Scott’s product to repair lines/cracks. Then recover the plaster with water based Stain Sealer paint (oil based could aggravate the problems). Again not the best course of action but Might work in a pinch. Good luck, Enjoy your house!

  9. Jamie on said:

    My daughter has a house that was built in 1902. The plaster walls have been covered with layers of wallpaper. She has been working on stripping the walls of the wallpaper and now has to repair the plaster that is crumbling and cracked in places. What would be your recommendation on how to fix the walls? She has talked about sheetrocking them, but I am not sure that would be the best solution.

    • Heart on said:

      Hi Jamie, Congratulations on your daughters purchase of an older home.

      I had original wallpaper on all the walls in my 1927 home too. Over the years the walls had settled & the wallpaper was showing the cracks behind. I chose to remove it as well, it is tedious but well worth it. The feel of the plaster as it heats/cools is more preferable than drywall. I think she will be much happier with the end results. I would suggest taking photos along the way as it is a labor of Love.

      I would use the product Scott recommends for the repairs. Although I did opt for a complete drywall on the ceilings. With all the work I put into the walls, I did not want gravity working against me.

      Encourage your daughter to keep going, it’s well worth it!

  10. Chandra on said:

    We have a 1928 craftsman style colonial. We would like to hang some hooks at the back entry for coats, backpacks, etc. The plaster is cracked and crumbly in some areas. I would love to save the wall but I really need those hooks to organize our entryway. Is it worth trying to save or should we just replace with drywall in that area? Thank you for your opinions.

    • Chandra, repairing the plaster will likely result in a better base for installing those hooks. If it’s cracked and crumbly you can make a real mess by removing and replacing with drywall or you can repair it for less work and money usually.

    • Heart on said:

      I would agree with Scott. Repair the existing plaster as Scott recommends here on his website. Plaster walls provide more insulation, beautiful to the touch & authentic to the structure.

      If I might make a suggestion (?) Consider installing a horizontal 1″ x 4″ painted board on the wall with the hooks attached. This will hold up better to the wear/tear of traffic & the board will require less attachments to the original plaster that is prone to cracking.

  11. Sarah on said:

    We recently bought a 1940s home with plaster walls and plan to remodel our kitchen. I know that there will be wall damage from replacing cabinets and opening up part of a wall, and I’m trying to learn more about how to repair them before I hire a subcontractor to do it. My electrician said we have “plaster-on-plaster” walls, not lath and plaster, because they sound a bit hollow like drywall. Could you explain the difference between plaster-on-plaster and lath-and-plaster? And what that entails in terms of wall patching/repair? Thanks!

    • Heart on said:

      You might like this link: http://porch.com/advice/plaster-and-lath/

      Not sure what the electrician meant by “plaster on plaster” because in lath/plaster the lath forms the bond to the frame of the house.

      Perhaps his terminology was referring to ‘drywall on drywall’ (which would sound hollow) This addition might have been used to repair a section that was removed to match the depth of the remaining lath/plaster walls.

      • Sarah on said:

        We did some wall repair and found out that some of our walls are plaster-on-drywall actually. My electrician and plumber loved it because it’s easier to deal with than lath, but offers great insulation and strength compared to simple drywall. I never knew this existed before but am glad to know of it now!

        • Heart on said:

          Good to know, thanks for the update.

  12. vishal bhagani on said:

    how repairing my house wall for water damage
    nd totally wall in peeling
    give me idia for repairing wall
    nd which chemicals for use in my walls

    • Heart on said:

      Hello,
      Please answer a few more questions regarding your situation.

      1) Has your plaster wall been painted or wallpapered?

      2) Is the wall now dry & crumbling?

      3) or is the wall still wet from the water leak?

  13. richard arifi on said:

    is never possible to give a crafsmanship tip for plastering because each home bulding was touch by a personnel memory of a crafsmanp …

  14. Clara on said:

    Our home is a 1914 craftsman bungalow in the Pacific Northwest. Most plaster that still exists seems to be in decent condition, but the under-eave closets have plaster that crumbles under the pressure of the crow bar I’m using to remove some molding, extra nails, etc. I now have indents to repair and a section that had separated from the lath along a crack and is now in a pile on the floor. Lath is in good condition. Once I patch up the indents and hole (using gauging plaster as mentioned in this article?), do I need to put something over the rest of the walls to prevent future crumbling? I ultimately plan to paint and install a new closet system to finish the project. I have no idea what I’m doing…help!

    • Ameeta Alter on said:

      Clara, here are a couple of good resources: http://www.theheritagedirectory.co.uk. And, buildingconservation.com. Several articles that you and will find useful, particularly regarding materials. I have nearly finished with the removal of old lime wash layers, but simply had to test an area myself to figure it out. I used water to help saturate the old wash, and Lino cut tools to scrape and clean. The moldings were lime plaster cast, almost soapstone hard, and withstood the scraping. The water helps, and the more you saturate the top layers the better. No one really explains how this should be done. “Carefully” is all I got! This is for decorative moldings, but the links I suggest have lots more.

      • Heart on said:

        Thanks for the update Ameeta, thanks for sharing you tips too!

    • Heart on said:

      Suggestion: whenever using a tool to pry on plaster or sheet rock, place a flat metal spatula or 6″ drywall blade on the wall, place your crow bar or tool under what you are removing & use the flat metal plate (blade) to pry against. This will prevent damage to the walls. Hope that helps… <3

    • Heart on said:

      RE: crumbling walls/indents
      since it is in a closet, you can mark your stud locations with blue tape on the floor/ceiling, screw 1/8th inch sheet rock (over the entire wall) attach to the studs every 6-8″ on the studs. Now you can use the stud markers to install your closet system as well. Sounds like a nice project, have Fun! <3

  15. homesol on said:

    Liked the article too. It has been a headache to counter this crack problem. Finding solutions…found this article quite resourceful. Thank you

  16. homesol on said:

    Hi would be interested to know if one coat plaster was used,also are cracks appearing as straight lines or where the plasterboard joints are?? crazing and cracking would occur if only 1 coat applied,I would suggest you get a different plasterer to look at it for you in order to ascertain the problem. We hope this helps a bit, but without seeing it ouselves it is difficult to suggest a solution

    • Heart on said:

      Which post are you addressing? (use the reply button under the post)

  17. Heart on said:

    I have a newer (1927 craftsman) home with plaster walls/ceilings, untouched since it was built (original wallpaper).

    Wallpaper held the plaster cracks in the walls. Removed damaged wallpaper (photo/saved examples), patched plaster as Scott recommends.

    The ceilings in the Kitchen/bath had 2’x4′ areas where the plaster was missing on the ceiling.

    I opted to drywall the ceilings over the plaster to create a flat ceiling. Molding replaced, you’ll never miss that 1/2″ 😉 & we won’t have gravity working against us. Hope this helps.

  18. Jim Dowd on said:

    Scott,
    We live in an old(1809)place in MA,near the coast. Redone before we bought it (thankfully.) The front hallway, up the stairs and the second floor hallway are untouched historical murals done on plaster in 1835. Showing cracks going up the stairs, someone long ago attempted some repair with poor results leaving stripes of light plaster and the cracks. I do not believe the plaster has “delaminated” from the lathe. At 200+ there is not a straight line in the house (the foundation and roof are sound.I’d like to stabilize the cracks and see about getting someone to touch up the results. I know there are some “Porter” experts around to do that part. I don’t have the resources for a full on restorer

  19. Erin on said:

    I have a question about re-skimming. We have the top floor unit of a converted 1895 mansard single family. Ceilings and walls are all original lime with a century’s worth of paint, unevenness & some de-laminating finish coat. I can repair de-keying with big wally’s and remove finish coat on de-laminating areas but am concerned about skimming. Ideally I’d go down to original & skim new lime finish but I’m also likely dealing with underlying lead paint simply based on age. I thought about applying a bonding agent and re-skimming especially since the walls already have modern non-breathable paint but I’ve seen conflicting reports about PVA bonding agents for old lime plaster. I would greatly appreciate any advice/experience. Thanks!

    • Erin, most if my experience is with gypsum plaster which was more prevalent after the 1880s. I would speak with the folks at limeworks.us about the best bonding agents for your situation.

  20. Ameeta Alter on said:

    We live in an old colonial house about 180 or more years old. I have been slowly restoring it over the past 9 years, and am now at the point where I want to restore the hallway which has a lot of lime/plaster moldings. Original walls are made of stone,& mud & are almost two feet thick. Plastered in lime and whatever was used back then. Problem: although most of the molding is well preserved, it is under hundreds of layers of lime wash. I would like to remove as much as I can without damaging the designs.The location is North India, in the mountains. minimal resources. Caustic soda was suggested, but I am wary of doing anything without professional advice. Any suggestions?

    • Ameeta, I don’t have much experience with that but I would ask the guys over at Limeworks.us because they know just about everything when it come to restoring historic plaster and masonry.

      • Ameeta Alter on said:

        Scott, thanks for the reply. I know it’s a complicated thing…and it will be wonderful if someone comes up with a solution. I will keep looking and asking meanwhile, and will let you know if annoying turns up.
        Ameeta

  21. Greg on said:

    The problem is, where do I buy repair products? I need to just patch some small cracks and a couple of small sections where the skim coat has come off, but my choices from the local stores are plaster of paris or spackling. I’ve tried plaster of paris before, and you realistically get about 10 to 15 minutes of work time before it hardens, plus, I don’t think it is as high a quality as the original plaster. Where can I buy real plaster?

  22. Amy Hogg on said:

    We recently bought a house built in 1900 and the ceiling in the living room (16′ x 20′) is loose. From the way he described it I believe the lathe has detached from the beams above it. My contractor said that this is fairly uncommon and he suggested drywalling over it. After reading this post I would prefer not to. Would he be able to use the process that you describe in “dealing with cracks” to fix this problem? I also have a built in bookcase in which the plaster is crumbling in all of the corners. I could use the Big Wally’s plaster magic that you describe in another post, right? Thanks for the advice!

  23. mike on said:

    My house was built in 1923. I have had plaster issues for decades. The roof leaked before I purchased the house ruining many ceilings. Covered all ceilings with sheetrock and then joint compound with several layers of vaneer plaster as there were high and low spots. They look great painted different colors. No white ceiling paint in my house.
    I used hundreds of plaster buttons to re-secure the wall plaster whereever needed.
    Anyway, my house was always very dusty. I finally realized, while skim coating the walls with plaster, that the old plaster behind the wood trim was/is deteriorating. The dust falls out from behind the wood at the seams due to random vibrations. I ran a thin bead of paintable tan colored caulking at every wood to wood and wood to plaster seam. My dust problem has disappeared and the house is much less drafty.

    • Interesting solution. Very creative! You have to be good at improvising with an old house.

    • Amy Hogg on said:

      We have the same problem with dust coming out from under the baseboards! Most of our baseboards are missing quarter round so I’m hoping it gets better once we get it installed.

      • Mike on said:

        The reduction of dust has been incredible!
        Apply before paint, use your finger to press deeply into seams and cleanup with a damp rag You cannot see the caulk at the wood to plaster seams. If you caulk the wood and stain it, use a caulk as close to the color of the stain as possible and it’s almost invisible. I got lucky, nobody ever painted my woodwork. It had a thick coat of something very dark on it (shellac?) and was severely alligatored wherever the sun hit it. Had to use a chemical stripper to remove.

  24. John Cadd on said:

    In a loft room I moved a doorway along the passage to avoid the door opening near the top of the staircase. It`s a lath and plaster wall.I had some spare uprights to make the supports. I started replacing the laths with the original nails.That`s a very noisy job. Then I switched to an experimental way with Sikaflex polyurethane sealant/glue. Much too expensive normally but a beautifully silent , simple way to rebuild a wall. Testing a few laths later in the week I found the sealant laths took about 3 times as much force to shift compared with the old nails. The nails were in very usable shape considering they had been there for one hundred years .
    30 years ago the roof was changed from terra cotta to concrete tiles. The electrician told me the loft was a mess! I discovered the plaster torching had been left there all that time. Over 6 tons of it hidden in every cavity and all held up by those tiny lath nails. Not one scrap was resting on a strong joist. All just hanging on old laths and nails .

  25. John Cadd on said:

    I am renovating an Edwardian house with a modern Limelite plaster.It`s breathable plaster and also insulates the walls. The dining room had hollow sounding plaster on brick walls. I cut a number of trangular holes about 4 inches each side to remove the hollow parts and attach the rest more firmly . The worst wall was all hollow (loose Drummy Render). Lime plaster does not stay attached to brick sometimes (often ). I cut a slot about 3 feet wide with a multi tool and then straight down to form a big oblong shape about 4 feet high. The section just fell off in one piece with a thud. The multi tool avoids any damage you might get with hammers and chisels . I had to remove 8 layers of gloss paint from the plaster walls in the kitchen. The house is becoming breathable once more after many years abuse .

  26. homesower on said:

    Good article. I am faced with a few ceiling cracks. I have been ignoring the for 15 years but would love to finally fix them properly.

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