5 Worst Mistakes of Historic Homeowners (Part 4 Plaster)

The walls of any pre-war house are most likely wood lath like in this picture covered with 3 coats of plaster. The work took a long time and was very labor intensive. Not to mention it required a skilled plasterer to make sure the plaster was properly applied and the wall was smooth and level.

Then when the GIs returned home from WWII the baby (and housing) boom hit America, and there was a huge demand for quick affordable housing. A new product was just beginning to get some traction in the wall covering business call gypsum board or sheet rock. It was a wall that could be screwed or nailed to the studs by a relatively unskilled laborer at close to twice the speed and half the cost of the traditional 3-coat system. And since this wall wasn’t applied wet like plaster it could be painted right away and thus got the nickname “drywall.”

A traditional 3-coat plaster is typically 7/8″ thick and when you add in the 1/4″ wood lath that supports the plaster wall you have a wall that is more than 1″ thick! Compared to today’s most common drywall thickness of only 1/2″, that is a difference worth noting.

Today the cost of a full 3-coat plaster wall is still expensive and timely to install, but when you live in an old house with one already installed you should try to reap the benefits of someone else’s labor all those years ago.

All to often we see historic houses gutted to the studs to install new drywall to replace the “outdated” plaster. Sometimes the plaster has been neglected past the point of no return, but most times it can be repaired. Usually it’s torn out in the name of insulating the wall cavities. But as with anything in the building trades, there is more than one way to skin a cat! In order to save folks the mess and expense of tearing out their walls we recommend removing a few clapboards on the exterior in order to insulate the house to modern standards. Remember, historic homes typically have no plywood sheathing under the siding so insulating with this method is just as effective plus it’s faster, cleaner, and much cheaper!

The Benefits

Here’s just a few of the benefits of having a real plaster wall to consider before you think about removing yours.

  1. Thicker walls mean better sound dampening.
  2. Thicker walls mean double the R-value of ordinary drywall.
  3. Wood lath serves to strengthen the wall by adding additional racking resistance.
  4. Plaster increases the historical authenticity and therefore resale value of a historic home.
  5. It’s already there! It’s always “greener” and cheaper to retain existing elements.

Hopefully, this has given you some things to think about when it comes to your plaster walls. If you’d like to read more about repairing and maintaining your historic home’s walls check out our video post How To: Repair Plaster Walls or our other post How To: Repair Old Plaster.

Read the rest of the 5 Worst Mistakes of Historic Homeowners:

Part 1 Windows

Part 2 Floors

Part 3 Siding

Part 5 The Details

 

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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

106 comments

  1. Jane on said:

    The 1930’s house I am buying does not have plaster walls nor sheetrock. It appears to have butt-joint wood over the studs, then a thin layer of cloth which has been wallpapered over. The wallpaper has been painted. What would you do to these walls? I am pretty sure there is no insulation either.

    • If you can I would probably try to get back to the original wood paneling. I love original paneling and it is usually quite beautiful.

  2. Matt J on said:

    I have an 1890 brick four square in Columbus Ohio. The third floor is a finished space. The knee walls and ceiling form essential the top 5 sides of an octagon. The walls/ceilings themselves are plaster on wood lath and are beautiful. That said, the third floor is cold in winter and hot in summer. I need to add insulation, and would like to do that without tearing out the wall surface. Behind the knee walls on all 4 sides is attic craw space that allow me to see there is no insulation in the space between the roof and plaster. Is it possible to blow in foam insulation of some kind? Had a contractor out that was pessimistic… Then never even quoted the job. Please let me know your thoughts so I can start shopping again from an informed position. THANKS!

  3. Tommy King on said:

    I did a demonstration of historic lime horse hair plaster at my church using a 4×8 ft small wall section and wood lathe. After three coats of lime plaster, scratch, brown, and finish, the 4×8 ft section weighed several hundred pounds! A similar section of sheet rock would weigh less than 50 lbs. Good demo of the strength and weight of lime plaster. I own an 18th century historic home in Southside Virginia.

  4. GS on said:

    I found this site while searching for an answer to my existing dilemma, and it looks like it just may be the perfect place.

    We have been undergoing a VERY long renovation of a 50’s brick cape in Southern CT. For those areas that we have needed to demo (and some we didn’t) we have been insulating and air sealing as we have been going, with great results. Now we are down to one last bedroom which is a 2nd floor bedroom, approx 180sf, plaster-on-gypsum board walls which are in excellent shape for their age. There are three exterior walls pretty evenly split between a 2×4 wood dormer and brick on 4″ cinder block with a few air gaps in between (this is one gable end of the house, with a reverse gable in front, also brick/block). The attic is insulated to R38 and we plan to blow in cellulose later to bring to R49. The 2×4 dormer walls are insulated with 50’s era balsam wool, which I’ll kindly say is better than nothing at all. The block portions are uninsulated save for the air gap.

    This bedroom when heated has always held heat fairly well despite itself, especially so now with better attic insulation. Where I am torn now is whether it is worth it to break down the exterior facing walls to properly insulate, or just to air seal as best I can (new windows have already been installed and trim is being replaced so I have access). My wife, whose patience has pretty well run out, has no further stomach for the typical dust/debris/hassle that doing this would bring. Me, wanting consistency, feel obliged to bring it up to modern standards, but I am also very tired.
    And therein lies the question. I have seen others suggest that demoing a wall just to insulate it is seldom worth the trouble, especially for a 2nd floor room with an attic insulated to modern standards. Does anyone have experience doing it, and was it worth it? As an alternative, I would be willing to consider other solutions if they are not too obtrusive or slow… the room WILL be getting SOME minor updating so drilling holes etc is not out of the question.

    • GS, rarely worth the time and mess or demoing everything to insulate those extra walls unless it’s already part of a major renovation plan. And when you say your wife is pretty down too that means it’s time to stop. Happy wife, happy life! That supersedes any restoration advice I could ever give!

      • GS on said:

        Thanks Scott that seems to be the consensus of the husbands I’ve asked! 😛

    • Pat on said:

      Pressing the restoration industry to create a drywall that includes aluminum layer inside could solve the problem of barrier-shield that Tyvek provides and prevents the need to remove horsehair plaster, insulate, and drywall – because insulation is meant to prevent warm air from escaping, and preventing warm summer air from entering. Preventing sun from radiating in summer helps to keep homes cool in summer.

      Density of plaster is great but doesn’t solve insulation problems of old homes.

  5. Dianna on said:

    Thank you for this article. we bought an old home with lath and plaster and made the mistake of having a painter come in and blow texture over the lath and plaster throughout the entire home. now, less than one year later the texture is cracking off the walls and ceilings. we are desperate for a solution that is low cost to fix this. Should i just buy spray adhesive and try and glue it back on? or do patch repairs where this is happening (30% of walls/ceilings)? Or should i start the process of removing texture – do you have articles on that process? Any thoughts greatly appreciated. Thanks. – Learning the Hard way 🙁

    • Dianna, removing the texture is the best way forward from my perspective. Scrapping the loose stuff off and making sure whatever remains is strongly adhered. Then skim coat the walls with either modern plaster like I mention on this site or use traditional veneer plaster and a bonding agent.

  6. Jenn on said:

    I’m going to disagree. Whenever you try to nail anything in to lath walls it bounces back at you. It’s far too much a safety hazard and annoyance to put up with if you don’t have to.

  7. Susan Sweigert on said:

    My house is brick veneer with lath & plaster walls (1938). It is set on a slope, with the bedrooms downstairs, and in one bedroom the wall is partly below grade. The portion of the wall below grade has constantly peeling paint & a bit of bubbling (the affected section is only about 3′ h x 4′ wide). What can I do to fix this & not be needing to skim-coat & repaint every other year? Note, the house is in Salt Lake City, and there is no groundwater problem. I’ve been told that this type of interior wall surface damage is a common problem with the masonry walls below grade in this area (that the cement used in that era tends to hold a slight bit of damp) and the only fix is to dig out & seal the exterior in the below-grade area (EXTREMELY expensive, no way).

    My neighbors had this problem & ‘furred out’ the wall, but the bedroom is already small (and it is the largest of the three b-rs, is basically the ‘master’ bedroom).

    • Susan, below grade paint peeling is almost always moisture related like you suspect. And yes I would recommend sealing the exterior masonry below grade. I know it’s expensive but it really is the only permanent fix that doesn’t create other potential issues.

    • Tim on said:

      Well, the hard way would be to remove the gypsum plaster that is problematic (almost all houses after 1910 or so have gypsum, not lime, plaster) and replace it with a lime plaster. Probably you’d want a plasterer to do this … how many square feet of wall are we talking about?

  8. Addie on said:

    I just received my copy of your book yesterday….I can’t wait to get started on my newly acquired 1925 Spanish Bungalow!!
    We are having Electric and plumbing updated. I am going to start refurbishing the windows and window sills!!
    So Excited!

  9. Tinna on said:

    What about putting drywall over the plaster? I was planning on taking all of the moldings and door frames down and just putting 1/4 drywall over it.

    • Elephant Insight on said:

      Terrible idea. You have a lot of labor, the hassle and expsnse of drywall and love your important classy reveals – the distiance between the flat surface and the curvaceous molding profile.

  10. Lauren on said:

    What do you suggest for insulation when there are not exterior clapboard but brick? Blown in insulation?

    • Lauren, you don’t want any insulation on the backside of brick because it is not waterproof. You may have a hard time finding an insulation that will work in your situation without it creating problems.

  11. Michael on said:

    What is your insulation workaround for a stucco house?

  12. DiannaRae on said:

    Thank you for this article. we bought an old home with lath and plaster and made the mistake of having a painter come in and blow texture over the lath and plaster throughout the entire home. now, less than one year later the texture is cracking off the walls and ceilings. we are desperate for a solution that is low cost to fix this. Should i just buy spray adhesive and try and glue it back on? or do patch repairs where this is happening (30% of walls/ceilings)? Any thoughts greatly appreciated. Thanks. – Learning the Hard way 🙁

  13. Jeana on said:

    I just purchased a 1905 Denver Square in Denver. I am just now deciding what to do with the plaster walls. I am a little confused by some of the comments. Can I get your thoughts about the following: 1- I don’t love the pattern of the plaster walls. I had requested that the contractor skim the walls. Is this a bad idea? If it is ok to do, what product do you recommend. 2- I also read that I should not use regular paint. Honestly, I didn’t even know that plaster had to have a different kind of paint applied. 3- A few of the ceilings had some water damage. The contractor is planning on just drywalling over the ceilings where there is damage. After reading this I am not sure this is a good idea for long term. 4- Lastly, some of the walls have lead based paint. I realize that I should not sand or eat the walls :), but does painting over them handle the problem? This house has been a rental for MANY years, has been run down, but still has so many charming features in tack. I am excited to take on this project! Convinced to keep my original windows. Meeting with a restoration company next week. Thank you for your help!

  14. John C on said:

    Hi Scott. Love the info you’re providing. Very helpful – thanks! Here’s my issue. I have a 1917 house in DC… Nothing special and fairly plain. The exterior is covered in asbestos siding. Something I’d rather not deal with a the moment, but I am working on the interior. I was thinking that I’d remove the plaster from the exterior walls, as it is not in the best of shape anyways (but not horrible) and that would give me the opportunity to insulate, add a vapor barrier, etc. Since I have asbestos siding, wouldn’t it be best to do it this way? I cannot imagine how much extra work my hvac has to do to keep up. Not to mention all the electrical work that needs to happen as well. What are your thoughts.

  15. David Crockett on said:

    Scott,
    What are your in depth thoughts regarding the removal of old Rock Wool insulation from an old 70 year old attic before adding new blown in fiberglass? I had always believed in the past that you should remove it all & start aknew to get the best & purist results. However, on this particular house I observed that by the time I got a section cleaned up & reinsulated eventually old farm dust from the local farming that seems to really be in high gear these days had just put more dust in there & the whole effort seems in vain. That being the case I began to question my previous logic, at least for this home. So then I wondered, is it really even necessary or worth it all or is it just a farce, so long as you clean up any heavy debris. The farm dust is going to get in unless you seal off every nook & crany & you don’t want to do that either by any means. What are your thoughts with pro’s, cons, & details. Thanks, Dave

    • David, removal of the old insulation is not necessary, but it does provide some good results. The old rock wool if it’s dirty and compacted is doing little good anymore. It is just taking up space that new insulation could be filling and providing beneficial R-value. Not to mention the potential health concerns if the insulation is filthy and soiled.
      In the end it’s not necessary, but it is often worth it to remove the old stuff first.

  16. Kim D on said:

    Thank you for taking the time to educate us on the value of historic homes. My husband and I just purchased a colonial home built in 1932, just outside of Portland, OR. The gentleman we purchased them home from is 97 years old! His parents built the home and it remained in the family until we purchased the home in Oct. After reading your article my husband and I decided to keep our plaster walls and NOT replace them with drywall. The issue we have is that 3 bedrooms have wallpaper that we don’t much care for and is in disrepair. What’s the best way to remove old wallpaper over plaster? Should we cover it up and paint over it? Also, the pain on the ceiling is peeling off – can we just sand down the areas that are peeling and epoxy over it prior to applying fresh pain? As the home was built prior to 1978 – we are almost certainly dealing with lead issues. We have small children so this is a major concern for us.

  17. Tim on said:

    I had (some) of my gypsum walls reskimmed with lime and rehabbed in my 1914 home. Used a limewash instead of paint and after some gentle sanding (800 grit) the walls are like colored stone. So beautiful! Never put house paint on plaster!

  18. william on said:

    Hi What is the fire rating for typical wood lath and plaster wall? I need to (hopefully) show the building inspector that it is 1 hour rated or greater Thanks for your help

    • It depends on the plaster material and thickness of the wall. I believe that a 1″ thick lime or gypsum plaster wall has a rating of close to an hour. Not sure where to direct you to for confirmation though.

      • andrew glover on said:

        OK, thanks!

  19. jill smith on said:

    We just bought a 1940’s house it has plaster wall I have read some of your comments but haven’t heard of anyone asking about asbestos in the plaster walls. I want to remove all the plaster walls only because we heard its very dangerous ? I assume they used asbestos in plaster in 1940 . How dangerous is this? I would like to keep the plaster walls…what to do.

    Thanks Jill

    • Jill, the only way to tell if there is asbestos in your plaster is to take a small 1″x 1″ chunk and send it to a testing facility. There is no danger with plaster walls unless they are crumbling and falling down, so I wouldn’t take it down unless it’s already falling down.

      • Jennifer on said:

        Hi, I am so torn. I am taking out the ’70’s kitchen in a 1866 house. The center interior wall is a 15′ brick wall with a chimney in the center. 1/4 of the wall has drywall over bad falling plaster and some broken brick. 1/4 of the plaster is in great shape, and the rest is rough with many bad repairs that no one cared about due to wallpaper.

        I believe in preservation, but I, also, like exposed brick in the right places. If I remove the plaster, it is gone forever. I am going for a free standing commercial kitchen look more for function of keeping country mice from setting up house under the standard kitchen cabinets.

        Help! I can’t decide.

    • Monique on said:

      Asbestos in plaster is not that big a concern as long as it is intact. The issue will be if you need to do repairs or are cutting into the wall. It is more likely that you will cause problems by removing the walls yourself. The biggest thing you’ve need to worry about is dust and crumbling pieces. If you are really concerned your should get it tested before doing anything.

    • Tim on said:

      Why on earth would you assume they used asbestos in plaster in the 1940’s? Do you also assume they used swiss cheese in house paint? Do you assume they used motor oil in crop fertilizer?

      • Tim, it was not uncommon to find asbestos as a binding agent in plaster walls in the first half of the 20th century. It’s not everywhere but it was prevalent enough that it bears some consideration.

        • Tim on said:

          Well, well, they sure did. Yikes. Thanks for the correction. It seemed crazy to me!

  20. Jean on said:

    I didn’t see this question covered above, but hope you can help. I’m living in a 1930’s frame bungalow with plaster walls/ceilings. The problem with the ceilings are peeling paint in small areas. Underneath the paint, however, it seems the plaster ceilings were coated with what looks like a lacquer and which might explain the peeling paint. Was this a customary way to treat plaster ceilings years ago and if so, once I scrape off the existing paint, what kind of primer and paint should I use. I’ve tried water-based primer followed by a latex in another room and while most seems to be fine, I did have a one inch, by two inch piece peel. I’m not sure if this was because I missed that spot with the primer or if I should have used an oil-based primer.

    • Marie on said:

      I have a128 house with similar problems, particularly in upstairs. if you scrape down to first coat or bare plaster, then rough sand ( 80 grit) and skim coat with 45 or 90 minute joint compound to feather out to intact paint surface. Use a stain covering primer like Zinnser ( use kind for new plaster, ask at paint store) and then paint. My upstairs bath had mildew in between layers of paint so I use paint stripper to take it down to bare plaster ( yes, entire bath ceiling), and then skim coated, primered and painted. it looks flawless and I am really happy with the results

  21. Joe on said:

    Hi Scott,
    I recently purchased an old Victorian style home here in Spokane, WA, that was built in 1903. It has lath and plaster. The only problem is that the lath and plaster in this home was done poorly compared to most. It is only 1/4 to 1/2 inch thick and there are cracks all over and in some parts falling away from the lath. My question for you in this case, is it worth trying to repair? If I were to replace with sheet rock what is the best method? Still has original crown molding trim throughout.

  22. PATTIANNE on said:

    Our house is over 100 but since it had been in the family we KNEW that there were layer upon layer (Dad painted his mother’s house regularly) of lead based paint we chose to cover the plaster walls (encasing) with wallboard/plaster board and restore the vat stripped heart pine woodwork. Not only could we not afford to have the paint on 12′ walls removed by remediation, we needed to move in as soon as possible after a move from west coast to southeast.

  23. andrew glover on said:

    A quick question…..I own a duplex that has a lath and plaster dividing wall, the City of LA inspector says I have to remove it and use 5/8″ drywall instead…is he correct?

    The lath and plaster seems(to me) to be far stronger than the drywall that he wants to replace it with. He is basing his conclusion on fireproofing.

    • Every city has its own codes, but your wall should be grandfathered in and not require changing. Besides that, a lath and plaster wall that is 7/8″ thick (which is typical) is much better at fire blocking than a thinner 5/8″ drywall. I’d get a second opinion!

      • andrew glover on said:

        Hey Scott, I DO plan on getting a second opinion however in LA nowadays there is no such thing as ‘grandfathering’ anything in. I keep hearing that phrase but anytime I have to deal with the city they pretty much tell me to take a hike! :-/

        Andrew.

        • jamie on said:

          wow, Andrew, that really sucks! you got a bad inspector. it happens. but definitely, if you at all can, keep trying to get a new one. we had 2 different inspectors talk down to our solar installers (a high-end custom company, sunpower, not assembly-line solar city) because they have a very sophisticated methods of running the conduit through the attic rather than across the roof and over the edge. they basically wanted to tell sunpower they needed to do it the way solar city does it, like they thought the company just on a whim tried to do something weird. they’re based out of CA, of course, and went to great lengths in advance to design hardware that’s compatible with building codes and safe for your roof. this is the Cadillac installation, not a fly-by-night hack job, but the first two inspectors talked about it like they were so certain, that this was wrong. sunpower had to call the city and complain that they’d gotten inspectors out who didn’t know they’d already gone through a pre-approval process *when they developed the hardware* and that they needed another person to come out and really listen to their explanation. third time was a charm, and this guy scoffed at the other two, saying there’s no reason they should have held up the approval. one of those previous two guys claimed to be a supervisor (but was apparently making it up?) and both had some sort of power trip thing going on. so in L.A. it seems like you can get inspectors who are just against things, and determined to make your life hard, even when it is not warranted, so you have to just fail your inspection and call to schedule a new one, trying a time slot when you think that same guy won’t be available.

          • Funnily enough I had a slightly similar issue with a DWP inspector…he said I needed to take the power line that ran through the attic(as they all were done in the 20’s etc) and run it outside the house. This would involve moving a gas wall heater as the chimney/vent would be in the way and then having ugly cable running the length of the house. In the end he went away and nothing happened and all is well 🙂

  24. Steve Fischer on said:

    Nice bunch of comments. I live in circa 1903 colonial. Over 20 years ago had the first floor gutted & sheet rocked by talented professionals. Also included was new porch damaged by Yankee gutters, cedar siding, roof & flooring. The upstairs bedrooms were left alone except for small sheetrock repairs.
    About 10 years ago I removed wallpaper & used plaster washers (a lot) to bring the walls of an upstairs bedroom back together along with a small amount of plastering. The ceiling was fine. I taped & used a lot of joint compound to finish. I sanded with a porter cable disc orbital sander attached to porter cable shop vac. It turned out perfect & has not shown any cracks & was painted.
    Recently (time flies), I finished two tandem rooms upstairs. This time where the damage was severe I used my Fein Sander with the circular cutting blade to cut out the large rectangles of damaged plaster & fill in with sheetrock. This worked out very nicely. Also used plaster washers with sheetrock screws along cracklines (a lot). Again had to use quite a lot of joint compound mainly to level out the repaired plaster walls. This time, two hairline cracks have surfaced, been repaired.
    One little problem surfaced with sheetrocking over lath is that not all lath is either set the same way or the same thickness so either rip out or sand that piece or make an adjustment on the sheetrock .
    Finally, just did a closet where the ceiling was shot, so sheetrocked that. I used ceiling washers on the rest, but the left side was so out of level that I had to put way too much compound on it & spent too much time on it. I should have ripped it out & sheetrocked it.
    When the first floor was done, I insisted that all the plaster be removed for the new sheetrock & they also took the lath out. Insulation was blown in at the time through the outside boards as all the old siding was removed. Everything looks great with a combination of fixing plaster & sheetrocking.

  25. tim prater on said:

    should sheathing be installed after clapboards are removed? I already gutted and drywalled the dried out plaster years ago. Iv’e painted and caulked the old cedar claps with good paint.

    • Sheathing isn’t necessary if the house didn’t have it originally. You may end up with complications reinstalling the siding around windows and doors if you do add it. I would probably add some building wrap or at the minimum 15 lbs felt paper before reinstalling the siding though.

      • Kristin Tant on said:

        I have drywall over the old plaster walls. Im thinking I want to tear off the drywall to have the plaster walls? Or am I going into a big mess?

        • Kristin, it really depends on what is hiding behind the drywall. You’ll never know how good or bad the old plaster is unless you pull off the drywall. It just depends how much you want that plaster.

          • kristin on said:

            Well, I really really want to see what is there…..along with the wood floors. In some rooms they have put new hardwood over the old hardwood floors….looks like they did it about 40 years ago. Big project!

  26. Pablo on said:

    Okay – I have paneling over plaster and lath – and I’m scared of what I’ll find when the panel is removed. I’m thinking of doing a lot of molding/wainscoting – do you still recommend preserving the old plaster above the chair rail?

    • Pablo, it really depends what kind of condition the plaster is in. If it’s still generally intact why not save yourself the trouble of removing (a very messy job) and replacing with an inferior product like drywall?

  27. PFR on said:

    SHould I consider DRYWALL replacement to repair my plaster walls and ceilings damaged in plumbing disaster.

    My 75 year old historic home (Stanhope Johnson, architect) in Central Virginia has suffered a terrible “water loss” disaster due to plumber error. As a result we were forced to pull down plaster walls and ceilings on three floors.

    Trusted contractor suggests we should make repairs using sheet rock mudded up to match original plaster materials.

    I understand the issues of cost, mess and manpower, and LEAD TIME needed to even get someone in to our little town to effect a proper plaster repair, but I can’t help but feel this proposition is just adding insult to injury.

    Does it really not matter because it will ‘look the same” in the end? Is the ‘similiar look” in the end product enough of a reason?

    What am I losing by not repairing to original spec?>

    I am sure there are lots of answers on both sides of this issue, but my most trusted voice (my contractor) has a very specific opinion weighed to the sheet rock side of the equation.

    Anybody got opinions, or even better, experience with this kind heartache?

    • Most contractors will usually recommend Sheetrock because it’s familiar, readily available and they know how to work with it. Chances are they have never hired a plasterer in the past. If a skilled plasterer isn’t available then this his idea isn’t a bad one. In this scenario I would suggest a veneer plaster setup. 5/8″ thick plaster board is installed first (just like drywall) and then a thin (1/8″) veneer coat of plaster is installed over top in whatever texture you desire. You will need a plasterer for the veneer coat but the overall expense should be lower than doing a traditional 3-coat plaster wall.
      Using plaster instead of drywall mud is important for performance and texture. Plaster is MUCH harder than drywall mud. It provides superior abrasion and dent resistance. Maybe not that important for a ceiling but for walls you want that improved performance.

  28. Oma on said:

    Love this article. We are considering buying a home with plaster walls. They look solid, but have some mildew stains. First thought was rip out walls, install insulation and drywall. But after checking out this article and the one on vinyl siding (which is on this home), I wonder what the problem really is and how to fix it. I hate damp walls and mildew.

    • Oma on said:

      Forgot to mention, the house is from the early 1800s. Also worried about lead and asbestos.

      • Make sure you hire a EPA certified firm to do any repairs on the house so you and your family are protected from lead. As for asbestos there is no way to tell without testing . But asbestos wasn’t used in the US until the late 1800’s.

    • Oma, a good HVAC system and possibly dehumidifier will do wonders to hep with your mildew problem. Mildew will grow on drywall just like it would plaster so go for the source of the problem not just the symptoms. If you have moisture issues it might be the vinyl siding trapping vapor, a leaky roof or siding, leaking pipes, or any number of things. Somehow moisture is getting in and it can’t escape. That’s the problem to solve. Good luck with the house!

    • Tim on said:

      Wow, probably the mildew is from blown in insulation with no vapor barrier. As far as I know, there isn’t an effective way to insulate the exterior walls with plaster walls and no vapor barrier. It isn’t that big of a deal and I would never, ever remove plaster just to insulate. Just insulate the attic well and remediate all air intrusion elsewhere.

  29. Smitty on said:

    Question instead of comment. I have gone all the routes described above in many rooms of our 1832 Greek Revival, but am at an impass in a northeast facing bedroom. The outside walls seem to be more sand than plaster and will never stand a coat of paint. The interior walls are already down to the lath due to great variations in plaster depth which made repair next to impossible. I will use 5/8′ drywall and should get a good reveal at the two doors.The outside walls do not demonstrate the breaking of keys as did the partition walls. Maybe because the interior walls flex more easily. I would like to avoid removing the plaster from those two outside walls and just skim a veneer over them when I do the rest of the drywall.

    Now the question. Is there a difference in the type of plaster used on the exterior walls as opposed to the partition walls? Is there any vapor barrier behind the plaster on the exterior walls? Would it be worthwhile to tear the old plaster down and install a vapor barrier then drywall as the other two walls?

    I am taking a two day break from this project, so replies can be well thought out and critical. I will get over anything you beat me up on!

    Thanks,

    Ed

    • Ed, the plaster should be the same composition and thickness on the entire interior of the house. Due to the age of the house there won’t be a vapor barrier, but you can definitely add one if you’d like. It’s not quite as effective obviously unless it completely encompasses the house. We use a veneer plaster over top the 5/8″ drywall to help it blend in better with the existing walls. And if you have a sanded finish which it sounds like you might then you can always just add simply play sand to your plaster mix.
      Personally, I would try to save as much of the original plaster as possible, but you’ll have to decided what is reasonable considering the current condition of the walls.

      • robin on said:

        hi scott. i’m really appreciative of all the work you’ve put into your website and all the valuable information. i am now an eager subscriber! i’ve been digging through the archives and your book. we are in the process of purchasing a 23 acre farm and with it a rather large 1870s “farmhouse”. the inspection is just around the corner on memorial day. i was glad to read your tips for inspection and what to make sure to learn about old homes. that was a great find to make as i researched plaster restoration which brings me to my question. i would like to get down to the original plaster and finish with, instead of paint, a lime wash. i love the texture and irregularity of plaster walls. my question is this: am i understanding correctly that the best course of action is to remove the wallpaper -where it exists- check for the soundness of the plaster beneath and chemical strip the paint and proceed with repairing the plaster? if i don’t intend to paint over the plaster do you have different recommendations for plaster repair (and how to determine if it needs to be repaired?) thanks again for all of this timely information about plaster!

  30. Chris on said:

    I couldn’t find a reasonably priced plaster contractor, so I put up drywall. The house was a rental property (a lot of holes) and the walls were significantly damaged by cellulose being blown into the wall cavity. The insulation settled and coupled with poor maintenance and rainwater management, I ended up with a soggy-mess of a wall. It can be hard to tell a wall is a damaged behind so many layers of paint (I missed it during inspection).

    My question is how should I go about replicating a plaster finish on the drywall? Slightly uneven skim coat and sand? Any recommendations would be greatly appreciated.

    • Chris, I like a modern plaster finish on top of drywall to get the look of old plaster walls. We use a 50/50 mix of veneer plaster and pre-mixed joint compound. You need both in order to have it hold properly on regular drywall.
      Mix them together and apply like you would a veneer plaster finish. Trowel it on and knock down the high points after it sets up. You can add sand to the mix if you would like the added texture. It’s hard to describe the whole process in a comment. I plan to put together a video soon to teach how the process works.

    • Tim on said:

      Adhesive such as plaster weld and gauged lime plaster. Why rough? Plaster should be glass smooth.

  31. PCL on said:

    I think John Townsend has the right idea. Do each wall and ceiling on a case-by-case basis, with an aim of preserving as much as possible. There is nothing wrong with using plaster screws and glue injection to stabilize a plaster wall, if it holds together when it’s done. But there’s also nothing wrong with drywalling over a problem wall, if all the door and window frames are shimmed to match the new wall thickness. Drywalling over a plaster ceiling is a great way of making it safe, especially with mid-century “transition” (rock-lathe or expanded mesh) ceilings that tend to collapse catastrophically and can be quite dangerous. And if you really have to get into a wall (insulation can be blown, piped or even stuffed through holes, but dangerous wiring can require much more demolition), it’s no big sin to replace the plaster on that wall with drywall; you can even use 5/8″ or even 1″ (usually double 1/2″ layers) to replicate the solid feel of plaster. If you do a good enough job of either resurfacing plaster or taping/mudding drywall, it will be impossible to see which walls are which.

  32. Connie on said:

    One note to the comment above concerning replacing drywall where plaster and lath was removed………… If the wall has doors or windows it’s likely you’ll need to fur it out . Even if you’ve been lucky enough to remove the door & Window trims without damaging them ( we left ours in place) the jamb thickness is going to dictate where those trims need to be. Most of our Jambs are at 6″ width. You can fur out the trim but the profile looks ” off ” next to the wall and base trims………. tried that first……… Rip out, redo

    • John Townsend on said:

      All you have to do is fur out the studs enough to have the drywall at the same depth the original plaster. Example: if you find that the lathe is 3/8 thick (very typical) and the thickness of the plaster to be 3/8″ thick (also quite typical) then you can fur out 1/8″ and use 1/2″ drywall. Your trim will fit exactly as before. I assuming one can carefully remove the trim.
      Alternatively you can hang 5/8 drywall directly on the studs (remember the lath = 3/8″ + plaster = 3/8″ == 5/8″ total thickness.

  33. Connie on said:

    We have 2 homes in Galveston Tx circa 1884 & 1887. Both are baloon framed houses and after much research an convinced that filling them with insulation could put the structure at risk for moisture damage. The walls were designed to breath and the plaster to insulate. One problem some walls had to be removed to re plumb & re wire (permitted) and we’re faced with several problems. 1, most all plaster and lath is furred out before the laths are applied adding to the depth deficit in replacing the wall. 2 , the insulating qualities of that thick P&L is gone and lastly , replacing the wall so it finishes out to the same depth as the previous wall so your window & door trims reinstall at the same depth.
    Out depth from bare stud to door & trim casings is 1-1/2″ thick . The solution from INSIDE the wall 1st 4’x8′ T&G XPS , then 7/8″ drywall on top. We finish out at the exact same depth as the old wall, create a barrier of insulation on the exterior walls while leaving the framing open to breath. I contacted Dow Chemical in Midland Michigan, they were incredible in running the norms based on our zip code and making recommendations to us on what to use…………hope this helps others in the same quandary

  34. Bethany on said:

    I wish I could have kept my old walls. Too bad previous owners nearly destroyed it!

    If you have a historical home.. an old home. Do what ever you want. Anything! But whatever you do I hope that it’s good for the home so that it WILL out last the current crop of new homes with built w/ oriented strand, chip board, MDF crap et al. …

  35. John Townsend on said:

    In the first place the difference in R- value between plaster/lath and drywall is nearly insignificant with respect to the TOTAL R value of the wall itself, assuming there is insulation. There is also only a minor difference in soundproofing. In the second place drywall over plaster utilizing 2 1/2 screws into the joists is a very practical idea for ceilings. Notice I said ceilings but NOT walls. Care to have that plaster dropping down on your head from time to time as it degrades over time? How about getting up there to rip out that ceiling plaster so as to either replaster it or drywall it? You can repair the plaster or replaster but there is no advantage save EXCEPT from a purists’ historical standpoint. Other than that there is absolutely NO ADVANTAGE in plaster on the ceilings. I hung drywall over plaster on the ceilings in our 1935 Craftsman bungalow. The only drywall on the walls is in a couple of places where the plaster had come loose Patching as it were. Other than that the walls are original.

    • matt on said:

      re: drywall patches on your plaster walls…as carol describes above, you can repair broken plaster keys with plaster screws and skim coats.

      • John Townsend on said:

        Yes, you can repair broken plaster keys with plaster screws and skim coats. But you’ll have to keep doing over and over and over. Not in the same place:
        Here, there, over there, here, over here, there, here, in that corner; Get it? Plaster/lathe walls (especially ceilings!) DO THAT. It’s in the very nature of the material. Continually cycling – settling, streching, compression. In essence, living to OLD AGE. Moisture, Heat, Cold, Seasons, Plus it’s just brittle material (why did they need horsehair in the first place?? The fore runner of fiber reinforcement to counteract these forces) How do I know? 1) Many years in the drywall trade when I was a youngster. 2) I now own a Craftsman Bungalow
        built in 1925. Not to mention a degree in Mechanical Engineering much later life. Except for historical homes where it IS A MUST the plaster be maintained, or st Monticello or the White House
        or the like, it is highly impractical (especially ceilings over the course of ordinary homeowner ownership, say for even twenty or thirty years) Lastly:
        1. sound dampening.
        2. R-value
        3. additional racking resistance

        The lathe are flimsy and weak by themselves by virtue of age and the plaster brittle (remember the “keys” in plaster always cracking and breaking off?)
        are structurally only marginally better with respect to 1/2 drywall. If you’re that concerned about those conditions above, use 5/8″ on the walls and 1/2 on the ceilings.
        R Value? might be worth a buck or two ( not much) off your energy bill. Why? Look at the TOTAL value throughout everything through the wall!
        I won’t bother with soundproofing argument – because if the walls are 90 years old, as in my house, the plaster/lathe has settled, cracked, expanded, contracted to such a degree that any sound proofing characteristics are rendered insignificant.

        • John Townsend on said:

          While I’m at it, if we want to be architecturally and period correct, why don’t we keep in place all the KNOB-AND TUBE wiring? I mean, if you going to keep all the plaster let’s also keep the KNOB-AND TUBE? I mean, WE”VE GOT TO BE Historically ACUURATE! Yeah!

          • John, should we also make sure to replace crumbling asbestos insulation with new asbestos insulation? There is a line between keeping historically accurate materials and keeping dangerous materials. I don’t think anyone has ever been killed by their plaster walls.

          • John Townsend on said:

            “should we also make sure to replace crumbling asbestos insulation with new asbestos insulation?” Exactly my point! I was being tongue-in-cheek. (not to mention the fact you CANNOT EVEN BUY NEW ASBESTOS INSULATION) In my Craftsman Bungalow I took out EVERY SINGLE knob and EVERY SINGLE tube and rewired it myself with 12ga romex, running 37 circuits, from a new 200 amp service panel. Knob and tube in and of itself is not dangerous, but it is highly impractical. I won’t get into all the reasons why. But preserving plaster just because it isn’t dangerous and supposedly adds the resale value? (not mentioning that there’s almost certainly underlying coats of lead paint on that plaster). Money is much better spent on preserving all the wood trim both interior and exterior, solid wood flooring, original doors and windows and wood siding because that is old growth wood which can’t even be purchased today unless it’s reclaimed. And like I said you’ll be fiddling around repairing that original plaster here there, everywhere, over there, over here, on and on; due to the structural problem of the “keys” of the plaster always cracking, weak structural characteristic as a brittle material, lack of fiber reinforcement.

          • John Townsend on said:

            I should have added that one doesn’t HAVE TO remove every single knob and every tube as I did. You can disable the knob&tube system by just cutting both ends of every knob and tube circuit and removing any and all parts of it you can get to. Then running all new wiring. Advantage? In my case, each room on it’s on circuit fully grounded, 20A minimum, GFIC’s wherever required as well, with plentiful outlets & switches everywhere.

        • John Townsend on said:

          One more thought:
          If you find yourself in the situation like that in the picture at the beginning of the article where you have all the plaster removed, but not the wooden lath, REMOVE THE LATH. It’s not worth it and it only adds to your problems of the hanging drywall. Furr out as necessary. If you want leave the lath and recoat with 3 coats of Plaster etc. —-> you are going down a foolish wrong road (in the long run) unless this is a historic building like Monticello or the White House.

  36. Elise on said:

    Howdy just wanted to give you a quick heads up. The text in your content seem to be running off the screen in Safari.

    I’m not sure if this is a formatting issue or something to do with web browser compatibility but I thought I’d post to let you
    know. The layout look great though! Hope you get the problem fixed soon.
    Many thanks

    • Thanks Elise. Editing and formatting is a full time job it seems. 😉 I appreciate the heads up!

  37. Yes! Plaster, all the way! My husband thought I’d lost my mind. To him, the best thing to do was rip off the old 70s paneling (gross!) and then hang drywall OVER the plaster! I nearly fainted.

    There are a couple rooms in this house where the plaster was apparently a bad mix. The scratch coat, which can be seen around some of our old door moldings, had reverted back to mostly sand and horsehair. One touch sent it crumbling.

    Not to be dismayed, I fought for the plaster. Since I do about 98.9% of the labor around here, I won that argument. That happens a lot! He buys, and I work. Seems fair.

    The first room was the master bedroom. There were areas popping loose from the lath because they keys were broken. Not shocking, since they’d nailed furring strips and paneling over it. In all areas besides the crumbling ones, I screwed the plaster back to the lath with plaster screws and washers, skimmed it with hot mud and fiberglass mesh, then skimmed it again. Hot mud wasn’t my first choice, but it worked really well. I’ve never mixed plaster, and I didn’t want to take a chance on my walls.

    The fiberglass (A trick I learned from This Old House) worked brilliantly for strengthening the cracks. Five years later, and those walls are still beautiful. The hot mud and a wide mud knife left a nice sheen to the walls that looks for all the world like the surface is plaster. It took a while to get a feel for the technique, and it’s a bit labor-intensive, but there’s no way I would hang drywall anywhere that I had a choice.

  38. Kim on said:

    In my Chicago 1920s condo, we have drywall OVER lathe and plaster, a truly unholy marriage! So hard to get anything properly fastened in the walls.

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