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All to often we see historic houses gutted to the studs to install new drywall to replace the “outdated” plaster.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 author. 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 son Charley.



  1. 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.

  2. 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!

      • 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! :-/


  3. 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.

  4. 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!

  5. 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?

  6. 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.

  7. 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!

  8. 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!



    • 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!

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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. …

  14. 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.

  15. 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!

  16. 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.

  17. 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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