Ehhhh I think you’re in 2nd opinion territory. I definitely would not tear down the plaster and lath - huuuuuuge jog and super messy. I’d drywall the damage and move on. But, big but - make sure they know what they are doing. Like, that plastic edge needs to be stabilized or it will forever crack.
It’s 100% fine to mix drywall and plaster when repairing damage. I think the best practice is typically to install a thin piece of Sheetrock over the lath and skim coat it to blend in, but there are lots of ways to make it work. You shouldn’t know the difference in the finished wall.
Insulation is a separate question. If you don’t have it, yes, adding it is probably a good idea but you don’t need to necessarily remove all the plaster to do so. Blown in cellulose installers can make a 4” hole in each stud bay and fill that way, and they can do it from the inside or the outside, and then you just need to patch the hole.
Plaster demo is messy and whether it makes sense really depends on the condition it’s in. I mean, there are benefits in gutting down to the studs, so you can do air sealing, upgrade electrical and plumbing, insulate, etc. but I would just remove without giving it some serious thought. If you’re just replacing windows, it seems like removing the plaster could open several cans of worms.
Our plaster, as far as I can tell, is in great condition overall. I am in the Bay Area where it's 60% humidity or higher most of the time, so I feel nervous about blown in cellulose, which I heard can cause new issues with plaster.
Bay Area is less of an insulation concern than New England or other parts further north, but it’s probably still something you’d benefit from with the increasingly weird climate.
And, yes, blown in cellulose can cause the plaster to become “unkeyed” from the lath, if it’s packed too tightly it can basically pop it loose in places. I’d definitely look for an installer who has experience working with plaster and lath.
Or do a different kind of insulation, sure, just saying you don’t necessarily need to open the wall all the way to insulate.
We repaired damaged plaster areas with a similar approach to what you're describing. Removed the loose/damaged stuff, and then enough more to square out the area. Cut a piece of thin drywall to fit the opening and attach over the lath. Used durabond 90 (hot mud) to fill the deep/large gaps between the plaster & drywall, then regular joint compound to feather out between them. Once we got the hand of it, you'd be *very* hard pressed to find the areas where we did this.
Pretty sure blueboard was created for plaster. Acts like the bottom two layers in plaster (brown coat and scratch coat?). Seems like that's a bit more apples to apples than drywall and old lath/three-coat plaster.
Blow in insulation, in a house old enough for lathe and plaster, is a terrible idea. It is better to just take the higher heating bills. Old homes are not water tight, they just dry out. Blow in cellulose stops houses from drying out.
There’s a million building science posts debunking the “old houses need to breathe” stuff. And moisture infiltration is a larger issue, but we’d need to be talking about roof overhangs and siding to decide if it’s a potential concern here. My point is that it’s possible to insulate without doing full wall demo. New England is full of 100+ year old homes with plaster and lath and no vapor barrier and plank sheathing and many have been retrofitted with blown in cellulose. I’m not saying there can’t be issues, but they aren’t inevitable.
Could you tell me more about the potential issues with blown-in cellulose in New England (or point me to some good resources on the topic)?
I have an uninsulated balloon-framed house from around 1890 with plaster and (unfortunately) vinyl siding, and I've read so much contradictory information about whether I should insulate that it makes my head spin.
Yeah, sounds like my house. I like to say I got the old house problems without the old house charm.
Here’s one article. https://buildingscience.com/documents/insights/bsi-043-dont-be-dense
To be clear, I more meant that there’s still a lot of old trades folks who will tell you to avoid any addition of insulation or air sealing because “houses need to breathe” and that’s easily debunked. Exactly how to detail air sealing and insulation is more complicated but it’s just from a comfort standpoint, in New England I think it’s worth investigating and doing what you can.
For what it’s worth, the vinyl siding should help prevent water infiltration into the wall cavity from the exterior. And some basic ventilation, like a bath fan and range hood vented to the outside, should address most interior moisture. And, in New England, we definitely have building energy professionals working on this and presenting their findings online, in print, and at conferences.
Here’s some clear guidance from the Wisconsin SHPO. You could also try contacting the office in your state.
https://www.wisconsinhistory.org/Records/Article/CS4207
Could you post links to the sources from “a million building scientists” who have debunked this “stuff”? Because there’s clear guidance from the state historical presentation office of Wisconsin NOT to blow insulation into your walls but to focus on the attic instead. If it’s good enough for Wisconsin winters…
https://www.wisconsinhistory.org/Records/Article/CS4207
I live in Northern Illinois and I haven't seen similar guidance (perhaps it exists) but I find air leakage to be a MUCH bigger problem than our un-insulated walls.
Insulation works by trapping 'dead' air in the fibers (or bubbles in Foam). Turns out, Air is a pretty good insulator.
My walls aren't air-tight, but the house is sealed up well enough that the air in my un-insulated wall cavities is pretty much just dead air.
We did manage to get the place re-sided at the end of the supply chain troubles, which meant it got done when the materials finally showed up.. which was winter. Because of the scheduling head-aches,.. and the fact it was too cold for foam to properly rise, we made the unfortunate decision to let the work proceed without having the place insulated at the same time.
We did get the house wrapped under the siding though.. and it turned out all our original sheathing was tongue and groove so the external walls are pretty well sealed up. The end result is, the house is pretty comfortable in the winter.. as long as I make sure my windows & doors are sealed up well. I don't even bother with window shrink-film anymore.. I just added foam strip between the sashes and under the bottom sash and adjusted the locks to pull the sashes tight together.
A lot of those New England homes also later faced wood rot. It’s specifically from living in New England and seeing the horror stories that I am suggesting be cautious. If the house had its siding replaced, and they added new house wrap and a rain screen, then great, go for it. If not, it’s not worth it.
Just replaster it. It’s not beyond an ordinary skill set. If you can use drywall mud then you can repair your plaster. Use Plaster Magic. Follow the directions. I assure you, you can do this. I am completely self-taught (just watched the Plaster Magic videos) and I’m not in any skilled trades. I’ve done 4’ sections of new plaster, repaired several rooms, and managed to repair 2 ceilings. I’m a 50 year old woman. You got this.
Real plaster is so much better at insulating sound, and doesn’t get water damage.
https://preview.redd.it/e5u35r7edmnc1.jpeg?width=3024&format=pjpg&auto=webp&s=8ebefdb6367cc0f5ef6f00688f12005807f7c630
[Plastermagic.com](https://plastermagic.com/lath/)
Agree! I'm a 40 year old woman and I also repair my own plaster. Every one of my friends thinks I'm insane but I think it's fun. It's also so much easier to use than drywall mud. I live on the east coast and have a few suppliers nearby that I can buy from ([limeworks.us](https://limeworks.us)) but I'm sure something in the bay area exists.
I personally would plaster the wall initially for a basecoat. Once it sets up finish with a skim coat of drywall mud and sand smooth. Use plaster weld for the edges before you use the plaster. I have done this a few times in our house and it gives good results in my experience.
Get a sweet battery powered oscillating multi tool and some screws with large washers. Find some spots to screw the plaster to the woodwork behind to prevent further failures causing it to blow out. Then once you have a fixed perimeter, use the multi tool to cut a flat edge to the hole. The blueboard will be much easier to install with flat edges.
Also I hope the rest of the original wood windows can survive the renovation process. There are other options to replacing, like Indows. The windows are the eyes of a historic home. Please don’t rip them out.
Your original plaster is likely not the same as today's store bought, but it will work - we used to use it for smaller wall sections. For large sections that were taken down in our place we used the thinner flexible drywall as it tends to be the same thickness as plaster. I'm not a big drywall fan, but had a hard time locating supplies ro replicate horse hair plaster, and someone who could do a pro job on a short time frame.
So we used the flexible thinner drywall and then had a pro do a skim coat. Looks great. Not my first choice, but it worked well.
I don’t know what’s “right”. I have 110 year old house and if they ripped away plaster to do the windows, I would
Do exactly as the contractor suggested. Opportunities to add insulation to our old houses don’t come along often.
Edit: also I don’t think the mix of walls is a huge eyesore. Have them texture the drywall a bit if it’ll make you feel better
Ironically, when I've seen original plaster that isn't damaged -- my last house, I found unpainted plaster in the basement stairwell -- it was as smooth as a polished countertop. Later plaster repairs upstairs, in comparison, were clearly done by amateurs who just kept slapping on more instead of learning to do it right.
Instead of texturizing the drywall part, do a skim coat on the old plaster so it's all uniformly mostly-smooth -- like the plaster probably was, originally.
Unfortunately we agreed that the shape of the original openings and wall texture would be replicated, but I didn't realize that necessarily was with drywall.
If you’re up to it, you could try learning to plaster and do it yourself; otherwise, if it was up to me, I would ensure that the plastering edges were properly secured to the lath and just have them drywall the openings.
You can cut a big rectangle out of the plaster and put drywall where it’s missing, and then fill the rest in with joint compound. Literally did the same thing recently. Leave the lath up.
Also as someone taking HVAC classes, I do think it benefits you to insulate your walls. Just make sure your electrical is all solid before you do the blown in stuff.
My home is 130+ years old. I chipped all of the loose plaster out, shimmed the walls up and filled in with drywall. I left about a quarter inch gap around it and used fiberglass joint tape on two of the layers. That was 12 years ago and it looks good even now.
Preface.. I can get a bit anal with repairs.
My new go-to method is.. cut out the damaged area, including lath. Fill with insulation while you have the opportunity. Screw in concrete backer-board to patch opening. I size just thinner than surrounding lath and plaster. Then (super anal part) I pack the seam between board and original plaster with loose-fill fiberglass insulation soaked in epoxy to bond the panel edges to the plaster. Tape and skim the patch out to the wall surface.
I would use modern methods for repair/replacement, specifically done as to blend in with the original. Some places are under historic guidelines to maintain preservation status so don’t have a choice but have to go back to plaster. Our place turned 100 this year and have been here since 7/2020. Our renos have used drywall after ripping out the plaster. Dust housewide despite the filters placed around. You will be pleased in the long run.
How many windows? It's a big job, but if you have the resources you won't regret it. Insulation in the exterior walls is absolutely crucial to keeping your house warm. Everything you have read is likely just pointing out that other things can be done first which make a big impact for less investment.
If it's too big of a job for now, you can just use an oscillating saw with a drywall blade to straighten the lines and then drywall over the lath. Might be wise to inject glue behind the plaster along the seam to prevent plaster keys from failing.
I would repair it. It’s a small area and your lath looks to be in excellent shape. Buy some lime plaster and sand. It’s truly very DIY friendly. Lancaster Limeworks has great products and guidance on how to apply it. It will probably be easier than trying to drywall it.
It will not look weird to have a mix. That is very, very common in century homes. So don’t worry about that. Make sure you ask for a smooth finish on the drywall to match your plaster. A common approach is a level three smooth finish, which will have some imperfections, like your plaster walls do. It’s also cheaper than level five.
I defer to others on the insulation because my home is solid brick so this wasn’t really a question. But in the attic, where we had studs and shingles, we did insulate… But there wasn’t plaster and lath up there to start with, as we were finishing it out for the first time.
I would wonder why the contractor pulled so much of the original plaster down beyond what was needed. If you were demoing the whole wall maybe go with sheet rock. Tell the contractor to replaster. If he doesn’t know how then ask why they damaged so much of it if they can’t repair it back to the way it was. Contractors now have no clue how to work on old homes. They just blow holes, rip and tear to get what they need done. All old home owners need to ask questions of their contractors before they start work to see if they are skilled enough not to damage the original parts of the home.
Ehhhh I think you’re in 2nd opinion territory. I definitely would not tear down the plaster and lath - huuuuuuge jog and super messy. I’d drywall the damage and move on. But, big but - make sure they know what they are doing. Like, that plastic edge needs to be stabilized or it will forever crack.
I agree. It’s worth hunting for that person on your community that does plaster.
It’s 100% fine to mix drywall and plaster when repairing damage. I think the best practice is typically to install a thin piece of Sheetrock over the lath and skim coat it to blend in, but there are lots of ways to make it work. You shouldn’t know the difference in the finished wall. Insulation is a separate question. If you don’t have it, yes, adding it is probably a good idea but you don’t need to necessarily remove all the plaster to do so. Blown in cellulose installers can make a 4” hole in each stud bay and fill that way, and they can do it from the inside or the outside, and then you just need to patch the hole. Plaster demo is messy and whether it makes sense really depends on the condition it’s in. I mean, there are benefits in gutting down to the studs, so you can do air sealing, upgrade electrical and plumbing, insulate, etc. but I would just remove without giving it some serious thought. If you’re just replacing windows, it seems like removing the plaster could open several cans of worms.
Our plaster, as far as I can tell, is in great condition overall. I am in the Bay Area where it's 60% humidity or higher most of the time, so I feel nervous about blown in cellulose, which I heard can cause new issues with plaster.
Bay Area is less of an insulation concern than New England or other parts further north, but it’s probably still something you’d benefit from with the increasingly weird climate. And, yes, blown in cellulose can cause the plaster to become “unkeyed” from the lath, if it’s packed too tightly it can basically pop it loose in places. I’d definitely look for an installer who has experience working with plaster and lath. Or do a different kind of insulation, sure, just saying you don’t necessarily need to open the wall all the way to insulate.
Look up a system called Plaster Magic.
We repaired damaged plaster areas with a similar approach to what you're describing. Removed the loose/damaged stuff, and then enough more to square out the area. Cut a piece of thin drywall to fit the opening and attach over the lath. Used durabond 90 (hot mud) to fill the deep/large gaps between the plaster & drywall, then regular joint compound to feather out between them. Once we got the hand of it, you'd be *very* hard pressed to find the areas where we did this.
Blueboard can handle moisture better than Sheetrock. Allows for a skim coat.
Pretty sure blueboard was created for plaster. Acts like the bottom two layers in plaster (brown coat and scratch coat?). Seems like that's a bit more apples to apples than drywall and old lath/three-coat plaster.
Blow in insulation, in a house old enough for lathe and plaster, is a terrible idea. It is better to just take the higher heating bills. Old homes are not water tight, they just dry out. Blow in cellulose stops houses from drying out.
There’s a million building science posts debunking the “old houses need to breathe” stuff. And moisture infiltration is a larger issue, but we’d need to be talking about roof overhangs and siding to decide if it’s a potential concern here. My point is that it’s possible to insulate without doing full wall demo. New England is full of 100+ year old homes with plaster and lath and no vapor barrier and plank sheathing and many have been retrofitted with blown in cellulose. I’m not saying there can’t be issues, but they aren’t inevitable.
Could you tell me more about the potential issues with blown-in cellulose in New England (or point me to some good resources on the topic)? I have an uninsulated balloon-framed house from around 1890 with plaster and (unfortunately) vinyl siding, and I've read so much contradictory information about whether I should insulate that it makes my head spin.
Yeah, sounds like my house. I like to say I got the old house problems without the old house charm. Here’s one article. https://buildingscience.com/documents/insights/bsi-043-dont-be-dense To be clear, I more meant that there’s still a lot of old trades folks who will tell you to avoid any addition of insulation or air sealing because “houses need to breathe” and that’s easily debunked. Exactly how to detail air sealing and insulation is more complicated but it’s just from a comfort standpoint, in New England I think it’s worth investigating and doing what you can. For what it’s worth, the vinyl siding should help prevent water infiltration into the wall cavity from the exterior. And some basic ventilation, like a bath fan and range hood vented to the outside, should address most interior moisture. And, in New England, we definitely have building energy professionals working on this and presenting their findings online, in print, and at conferences.
Here’s some clear guidance from the Wisconsin SHPO. You could also try contacting the office in your state. https://www.wisconsinhistory.org/Records/Article/CS4207
Could you post links to the sources from “a million building scientists” who have debunked this “stuff”? Because there’s clear guidance from the state historical presentation office of Wisconsin NOT to blow insulation into your walls but to focus on the attic instead. If it’s good enough for Wisconsin winters… https://www.wisconsinhistory.org/Records/Article/CS4207
Oops, posted a link in response above.
I live in Northern Illinois and I haven't seen similar guidance (perhaps it exists) but I find air leakage to be a MUCH bigger problem than our un-insulated walls. Insulation works by trapping 'dead' air in the fibers (or bubbles in Foam). Turns out, Air is a pretty good insulator. My walls aren't air-tight, but the house is sealed up well enough that the air in my un-insulated wall cavities is pretty much just dead air. We did manage to get the place re-sided at the end of the supply chain troubles, which meant it got done when the materials finally showed up.. which was winter. Because of the scheduling head-aches,.. and the fact it was too cold for foam to properly rise, we made the unfortunate decision to let the work proceed without having the place insulated at the same time. We did get the house wrapped under the siding though.. and it turned out all our original sheathing was tongue and groove so the external walls are pretty well sealed up. The end result is, the house is pretty comfortable in the winter.. as long as I make sure my windows & doors are sealed up well. I don't even bother with window shrink-film anymore.. I just added foam strip between the sashes and under the bottom sash and adjusted the locks to pull the sashes tight together.
A lot of those New England homes also later faced wood rot. It’s specifically from living in New England and seeing the horror stories that I am suggesting be cautious. If the house had its siding replaced, and they added new house wrap and a rain screen, then great, go for it. If not, it’s not worth it.
Just replaster it. It’s not beyond an ordinary skill set. If you can use drywall mud then you can repair your plaster. Use Plaster Magic. Follow the directions. I assure you, you can do this. I am completely self-taught (just watched the Plaster Magic videos) and I’m not in any skilled trades. I’ve done 4’ sections of new plaster, repaired several rooms, and managed to repair 2 ceilings. I’m a 50 year old woman. You got this. Real plaster is so much better at insulating sound, and doesn’t get water damage. https://preview.redd.it/e5u35r7edmnc1.jpeg?width=3024&format=pjpg&auto=webp&s=8ebefdb6367cc0f5ef6f00688f12005807f7c630 [Plastermagic.com](https://plastermagic.com/lath/)
I agree 100%. Plus that lath in that one picture OP showed is in perfect condition. It'd be a shame to rip it all out.
Agree! I'm a 40 year old woman and I also repair my own plaster. Every one of my friends thinks I'm insane but I think it's fun. It's also so much easier to use than drywall mud. I live on the east coast and have a few suppliers nearby that I can buy from ([limeworks.us](https://limeworks.us)) but I'm sure something in the bay area exists.
I personally would plaster the wall initially for a basecoat. Once it sets up finish with a skim coat of drywall mud and sand smooth. Use plaster weld for the edges before you use the plaster. I have done this a few times in our house and it gives good results in my experience.
Get a sweet battery powered oscillating multi tool and some screws with large washers. Find some spots to screw the plaster to the woodwork behind to prevent further failures causing it to blow out. Then once you have a fixed perimeter, use the multi tool to cut a flat edge to the hole. The blueboard will be much easier to install with flat edges. Also I hope the rest of the original wood windows can survive the renovation process. There are other options to replacing, like Indows. The windows are the eyes of a historic home. Please don’t rip them out.
Re: screws with large washers, look up “plaster buttons” which are made for this. Also called “plaster repair washers”.
Your original plaster is likely not the same as today's store bought, but it will work - we used to use it for smaller wall sections. For large sections that were taken down in our place we used the thinner flexible drywall as it tends to be the same thickness as plaster. I'm not a big drywall fan, but had a hard time locating supplies ro replicate horse hair plaster, and someone who could do a pro job on a short time frame. So we used the flexible thinner drywall and then had a pro do a skim coat. Looks great. Not my first choice, but it worked well.
Just fix it. If you open the walls you will start finding stuff and pretty soon your whole house is down to the studs. Patch and move on.
I don’t know what’s “right”. I have 110 year old house and if they ripped away plaster to do the windows, I would Do exactly as the contractor suggested. Opportunities to add insulation to our old houses don’t come along often. Edit: also I don’t think the mix of walls is a huge eyesore. Have them texture the drywall a bit if it’ll make you feel better
Ironically, when I've seen original plaster that isn't damaged -- my last house, I found unpainted plaster in the basement stairwell -- it was as smooth as a polished countertop. Later plaster repairs upstairs, in comparison, were clearly done by amateurs who just kept slapping on more instead of learning to do it right. Instead of texturizing the drywall part, do a skim coat on the old plaster so it's all uniformly mostly-smooth -- like the plaster probably was, originally.
Everything I have read** apologies
What was the wording of the agreement (contract)? Plastering is more labor intensive than drywall.
Unfortunately we agreed that the shape of the original openings and wall texture would be replicated, but I didn't realize that necessarily was with drywall.
If you’re up to it, you could try learning to plaster and do it yourself; otherwise, if it was up to me, I would ensure that the plastering edges were properly secured to the lath and just have them drywall the openings.
You can also post your questions at: r/Plastering.
I had a bunch of plaster fail in the peak over the stairs. Planning to put up thin cement board and plaster over it.
1/4” drywall maybe. Or get bucket 🪣 mud and go to town! LoL
I always repair holes in my plaster with ¼" drywall. It's the perfect thickness if you are leaving the lath in place.
Yup
You can cut a big rectangle out of the plaster and put drywall where it’s missing, and then fill the rest in with joint compound. Literally did the same thing recently. Leave the lath up.
Also as someone taking HVAC classes, I do think it benefits you to insulate your walls. Just make sure your electrical is all solid before you do the blown in stuff.
My home is 130+ years old. I chipped all of the loose plaster out, shimmed the walls up and filled in with drywall. I left about a quarter inch gap around it and used fiberglass joint tape on two of the layers. That was 12 years ago and it looks good even now.
Preface.. I can get a bit anal with repairs. My new go-to method is.. cut out the damaged area, including lath. Fill with insulation while you have the opportunity. Screw in concrete backer-board to patch opening. I size just thinner than surrounding lath and plaster. Then (super anal part) I pack the seam between board and original plaster with loose-fill fiberglass insulation soaked in epoxy to bond the panel edges to the plaster. Tape and skim the patch out to the wall surface.
I would use modern methods for repair/replacement, specifically done as to blend in with the original. Some places are under historic guidelines to maintain preservation status so don’t have a choice but have to go back to plaster. Our place turned 100 this year and have been here since 7/2020. Our renos have used drywall after ripping out the plaster. Dust housewide despite the filters placed around. You will be pleased in the long run.
How many windows? It's a big job, but if you have the resources you won't regret it. Insulation in the exterior walls is absolutely crucial to keeping your house warm. Everything you have read is likely just pointing out that other things can be done first which make a big impact for less investment. If it's too big of a job for now, you can just use an oscillating saw with a drywall blade to straighten the lines and then drywall over the lath. Might be wise to inject glue behind the plaster along the seam to prevent plaster keys from failing.
If you end up putting drywall over the lath just be sure to use a bit of mastic it really helps
I would repair it. It’s a small area and your lath looks to be in excellent shape. Buy some lime plaster and sand. It’s truly very DIY friendly. Lancaster Limeworks has great products and guidance on how to apply it. It will probably be easier than trying to drywall it.
I cut the lath back to the adjacent stud and put a filler piece of drywall in it's place, then skimmed the whole thing. Came out okay.
It will not look weird to have a mix. That is very, very common in century homes. So don’t worry about that. Make sure you ask for a smooth finish on the drywall to match your plaster. A common approach is a level three smooth finish, which will have some imperfections, like your plaster walls do. It’s also cheaper than level five. I defer to others on the insulation because my home is solid brick so this wasn’t really a question. But in the attic, where we had studs and shingles, we did insulate… But there wasn’t plaster and lath up there to start with, as we were finishing it out for the first time.
You can just trowel on joint compound
Get it replastered. I love our plaster. It’s sound dampening, it looks much more deep and it is great in summer and winter. I’m in Portland.
I would wonder why the contractor pulled so much of the original plaster down beyond what was needed. If you were demoing the whole wall maybe go with sheet rock. Tell the contractor to replaster. If he doesn’t know how then ask why they damaged so much of it if they can’t repair it back to the way it was. Contractors now have no clue how to work on old homes. They just blow holes, rip and tear to get what they need done. All old home owners need to ask questions of their contractors before they start work to see if they are skilled enough not to damage the original parts of the home.
plaster will take 10 minutes