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. Sometimes I have the help of craftsmen from schlüsseldienst bremen during the renovation of the finish. You have to choose a craftsman who knows exactly what material is right for your historic house.
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All to often, we see historic houses gutted to the studs to install new drywall to replace the “outdated” plaster.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 are just a few of the benefits of having a real plaster wall to consider before you think about removing yours:
Thicker walls mean better sound dampening.- Thicker walls mean double the R-value of ordinary drywall.
- Wood lath serves to strengthen the wall by adding additional racking resistance.
- Plaster increases the historical authenticity and therefore resale value of a historic home.
- 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
Founder & Editor-in-Chief
I love old houses, working with my hands, and teaching others the excitment of doing it yourself! Everything is teachable if you only give it the chance.
I have an old house, about 100 years old with wood slat and plaster. Is there aspestos in that stuff? I’m tearing walls out and my lungs feel full of dust, I’ve been wearing a mask but I didn’t always have one on when knocking all the plaster off the slats. My walls look just like the picture above. Concerned.
Hi, Just purchased a home in Idaho built in 1918, it has plaster walls, but they are mostly in good condition.
The problem I have found is there is no insulation in the exterior walls. Taking off the outside siding and adding insulation is not an option, as the whole home was resided with stucco some years ago. I know blow in insulation is a bad option for exterior walls due to not having a moisture barrier. What are my options, other than redoing the exterior wall with dry wall?
Thanks
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!
There are spray-in foams usually sprayed flat into an open wall/ceiling cavity. You would want one that doesn”t expand, and I don’t know if they can blow it end-on into a long cavity. You need to google up a spray-foam contractor.
You’d be creating what is called a “hot roof,” with foam that is a moisture barrier filling the cavity, no ventilation. It’s legal here in Oregon, and I think it’s considered good practice, but it’s newish….
You could blow with fiberglas or celulose, but the problem there is ventillation between the top of the insulation and the bottom of the roof. If air can’t circulate under the roof, condensation can build up and cause rot. If there’s a way to get a water-vapor permeable (cardboard) baffle in under the roof, to maintain an inch or so air space, you can blow it, but the roofing nails usually get in the way.
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.
Excellent point Tommy!
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!
Thanks Scott that seems to be the consensus of the husbands I’ve asked! 😛
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.
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.
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.
Jenn, you should read this https://thecraftsmanblog.com/how-to-hang-things-on-plaster-walls/
Oh lord. You’re not supposed to hammer nails in it at all, ever. Not ever. You’re damaging the wall when you do that. Just drill a hole. I’ve never heard a worse reason to use drywall over plaster …
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.
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?
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!
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.
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.
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.
What is your insulation workaround for a stucco house?
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 🙁
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!
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.
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.
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.
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!
A plaster and lath wall has a fire rating of 69 minutes according to this HUD book “Fire ratings of archaic materials” (http://www.preservationnation.org/resources/disaster-recovery/additional-resources/HUD-Guidelines-on-Fire-Ratings-of-Archaic-Materials-and-Assemblies.pdf)
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.
OK, thanks!