Plaster is one of my favorite features in an old house and one that is easily overlooked. After all, how much do you really notice a wall or ceiling unless something is wrong with it. That being said, I think I can convince you to keep your plaster.
You may notice cracks in you old walls and gouges from years of hanging pictures and knick-knacks, but that doesn’t mean it’s toast. Did you know that lime plaster can even heal its own small cracks over time? We’ll talk more about that below, but for now, don’t feel like that old plaster’s done just because it’s old.
There are a lot of reasons to keep original plaster and below are the six biggest reasons in my mind why saving it is a worthwhile goal.
1. Plaster is Harder Than Drywall
If you put plaster and drywall head to head, there is no competition which is a harder wall covering. Traditional lime plaster has been slowly transforming itself back into limestone since the day it was applied. Traditional plaster walls are about 7/8″ thick compared to standard drywall which is 3/8″ gypsum plus a piece of paper on either side for a grand total of 1/2″.
That means a lime plaster wall would be nearly twice as thick as drywall and made of limestone! Which do you think is better at resisting dents and dings?
2. Plaster is a Better Insulator Than Drywall
We’ve just finished talking about plaster’s thickness so it naturally follows that the thicker the wall, the better the insulation it provides. Yes, your plaster walls likely have little to no insulation behind them, but the wall covering itself has an R-value twice that of drywall.
Being that 1/2″ drywall has an R-value of .45, there isn’t much to gain here, but every little bit helps, especially when the plaster is already there. Why remove it for something inferior?
3. Plaster is a Better Sound Blocker Than Drywall
Nobody likes a noisy house, and plaster is extremely helpful when it comes to reducing noise through walls. STC (Sound Transmission Class) is a rating for various wall assemblies used by the building industry. It’s helpful in comparing different ways of building and how they affect the amount of sound that transfers through a wall or ceiling.
1/2″ drywall on 2×4 wood studs has an STC rating of 34 according to National Gypsum. Compare that to a nearly 1″ thick lath and plaster wall which has an STC rating of approximately 52 according to US Gypsum. That’s an increase in sound blocking of 52%. Not bad for an old wall!
4. Plaster Can Self-Heal Cracks
It’s not a miracle, it’s just science. Lime goes through a curing process called carbonation which causes it to continuously be building and rebuilding bonds between its particles. No, it won’t heal big structural cracks, but small hairline cracks can heal themselves over time and I have seen it happen on more than one occasion. So, don’t count it out.
5. Plaster Removes Carbon Dioxide From the Air
I don’t know if it’s coincidence that as we have used less lime plaster and mortar in construction, the atmospheric concentration of carbon dioxide has continued to rise. I’m sure increased pollution and population growth have played a role too, but that doesn’t mean lime didn’t help.
Lime, the primary ingredient in historic plasters prior to the 1930s, releases water and draws in carbon dioxide as it cures. That process of carbonation we talked about earlier. It needs the carbon dioxide to help it turn back into limestone and so it continuously pulls carbon dioxide from the atmosphere little by little, as long as it is standing.
Sadly, gypsum doesn’t do the same thing. To me, that makes lime one of the greenest building materials ever invented. If that alone doesn’t convince you to keep your plaster, I’m not sure what will.
6. Plaster Lasts Longer Than Drywall
When you combine all these things together, you get a longer lasting and overall better product in plaster that has and will continue to stand the test of time. It’s no fun to replace walls and a lime plaster wall will need replacing less often than drywall, due to damage and age.
Even if the plaster is sagging or cracked, it can be repaired to last for decades more in the ways I outline in the video below. I’ve found that the reason most plaster is removed is because of homeowners and contractors simply not knowing it could be retained or repaired.
Put all that together and you’ve got a harder, more insulating, better sound blocking, greener and longer lasting wall covering that can be repaired. When you look at it that way why would you ever replace your plaster walls? I dare you…keep your plaster.
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.
21 thoughts on “6 Reasons to Keep Your Plaster”
I have 9” solid walls with ( I think gypsum plaster. The external walls when stripped have some crumbly surface but no damp or cracks. I want to increase heat retention of room a little without resorting to battening and thick insulation boards. So rather than just skim will dabbing regular plaster boards on help at all? Thanks
Hi there. The biggest issue for me is the knob and tube electrical that still is half of the house power and the cost of redoing electrical inside existing lathe/plaster walls. Other than that, I would love to keep for all of the reasons you suggest. Any tips on this? The extra electrical cost is worth it? Drywall patches done on openings for work just don’t look right.
live in albuquerque new mexico in an old adobe casita built in 1940, thick beautiful plaster walls throughout the home. Thanks for all the good info! 🙂
One very important attribute that you didn’t mention. When wet, plaster doesn’t grow black mold, like Sheetrock does. After seeing the devastation of hurricane Sandy, I really appreciate my plaster walls!
I am interested in hearing your thoughts on what to do when a house already has a mixture of plaster, plaster covered by drywall, and seemingly just straight drywall and needs a complete rewire and new plumbing. If you were in the owner’s shoes, how would you approach it? If you’ve run into this in houses before, how have you managed it and why? Thanks!
What is a skim coat?
how do you restore a bad skip trowel job?
Late to the party here, but aside from chemically testing it, how can you tell if your plaster is gypsum or lime? I live in a Chicago midrise (27 stories) that was built in the 60s. Are there any distinct characteristics that can help visually identify which type of plaster I have, or should I assume it’s gypsum due to when the building was constructed? The plaster is white/gray.
I live in an 1899 victorian with all original plaster walls that are in great shape. However, I get paranoid from time to time that my plaster ceilings will fall down spontaneously. Is this possible? Thanks
I JUST had this happen! 1920 Plaster finally gave way. The issue was related to moisture that had gotten into this small room over the last 20 years. The mortar in the bricks had totally disintegrated and… well… it was to be expected. The rest of the plaster in the house is beautiful… especially the interior walls where moisture and settling is not so much of an issue.
That said, you’ll know well ahead of time that the plaster is going to fall. It always starts with hairline cracks that get bigger and bigger usually resulting in sagging from the ceiling.
I have an old 1920s bathroom that is 100% mortar walls. I recently decided to put a niche in the shower wall. I removed the old tile, excavated out the old crumbly mortar and installed a box. I then repaired the area with hot mud plaster (Plaster of Paris) and coated that with 2 coats of Redgard. Then over that, modified thinset and tile. Did I screw up? Do you think I should have gone with a portland cement product instead of the plaster? Thanks.
With the redgard you should be ok, just watch the area for any signs of water damage.
I restored the plaster on many – most – walls in our previous 1912 house. There were some areas where I had to remove plaster down to the lath, so I would screw metal lath to the wood, build up the brown coat, and call in a plasterer for the finish coat. Very satisfying, although labor intensive. Not the ceilings, though. 3/8″ drywall with a skim coat there. I think the fact that the plaster was ultimately in such good repair greatly improved the value of the house when we finally had to sell it.
We wound up removing two interior plaster walls in one room and the ceiling. It was beyond repair and it makes me sad. I have tried calling several of the places in the area and they keep telling us they only work on old commercial buildings not residential. Makes me sad. My husband and I are trying hard to learn the trades but this is one we are scared of doing. Thanks for the fantastic blog.
We have sandstone and horsehair plaster but unfortunately we don’t have anyone local that knows how to repair it for us and some major holes from previous owners letting roof leak required us to take out walls to check stability of studs Any suggestions
And then there is the aesthetic of the slightly imperfect. Not only that is seen, but there is a cumulative viceral effect of all these retained surfaces… I find the difficult part is to know when to stop the resoration, and let the imperfections show. Wabi sabi sensibilities.
Thanks so much for info on STC and Insulation rating, all great selling points for an OLD house. We have a 1910 Craftsman and I wish I could find someone to install lath and plaster where the previous owners took out walls. I think this is a lost craft and one that will not be back. Such a shame.
There are very few of us left doing the old ways but hopefully it will ever die completely!
Amen to that I just moved to the Pacific NW and LOVE the old old homes I get to work on. I helped a local restoration carpenter in New England growing up as one of my first jobs and love the old Craftsman homes. Was relocated to Coastal NC for a long time and just missed those late 1800s early 1900s home. Grew up in an old Lathe and Plaster farm house in the Connecticut Valley and have such an appreciation for the tried and true generstion after generation homes and I stumbled across your blog and am so thankful I found it. Awesome information.
And firefighters love plaster walls. Our fire marshal told me that except to save a life, his firefighters do not go into newer houses, but old ones – yes.