The Cross House

Repairing Plaster Walls


The plaster walls and ceiling in the Round Bedroom are a helluva mess. Save the parlor and library, ALL the rooms in the Cross House look like this.


I had planned on simply filling all the smaller holes with sheetrock, and then sheetrocking over the entire ceiling. This is what I have done for decades.

But…but…this is the first old house I have ever restored which had radiators.

And what, you might ask, do radiators have to to with plaster?

Why, as I have now learned, everything: radiators, and plaster walls/ceilings, actually work in tandem. The former creates heat, and the latter absorbs it and then radiates it back out (something sheetrock does not do).

So, now I want as much plaster as possible in my house. Plus, well, I just love plaster.


STEP ONE: Putting back the lath. I did a post on this recently.


Holes re-lathed!


Last year, I had delivered two 5-gallon containers of plaster from Master of Plaster. I thought one was for the “scratch” coat, and the other for the finish coat.

Recently, my assumptions proved incorrect. It turns out that one container is the “base coat” and the other is the “finish coat”. The coats though are really just finish coats.

So, what about the rough “scratch” coat to fill in like a 1/2-inch of depth? Master of Plaster recommend I buy…





The product was SO not locally available. It was though easily available online. Walmart had individual bags available for $16 each with $16 in shipping…or $32 bucks a bag. Ouch.

Most everybody else had a 40 bag minimum order. Ouch. PLUS shipping. Big ouch. And each bag is 50 pounds! OUCH!

Then I found that Manards had a 20-bag minimum, about $13 a bag, and free shipping to a local store. Oh!

Hence, the ten bags seen in the above image. I have been taking 5 bags out of my car a day. At 50 pounds a bag, that is more than enough for my 61-year-old body. So, 10 down, 10 more to go.

NOTE: I have no idea of what I am doing. However, this is not the first time I have plunged ahead with something while having no idea of what I was doing and, yet, all usually worked out in the end. I figure that, in a month or two, I will be a friggin’ plaster EXPERT!  And my learning curve will be…fully revealed.


26 Responses to Repairing Plaster Walls

  1. WOW very informative thanks! My husband and I had NO idea about the plaster walls radiating the heat back! Who knew!!

    We have about half our original plaster and other half sheetrocked over. I DO brag on my plaster…I love it. No one really cares about it, lol. I do! Glad you do too. Good luck learning this old world skill

  2. You may already be aware, but the blog Old Town Home has done many posts about plaster repair with MoP! Probably a great resource 🙂

  3. My grandad was by trade a builder and plasterer in N. Wales! But he has long since passed on. Good to see that somewhere those skills are still valued!!

  4. Hello, Ross from St. Joe!

    I am having my plaster repaired in my back bedroom repaired as we speak. John Rodgers of Phoenix Restoration is doing the work and has documented some of the work he is doing in the Old House Fix group on Facebook. Once the holes and weak areas were repaired, he applied a pink plaster adhesive to the ceilings and walls. This is so the base coat has something to adhere too as there was a base coat of paint on the original plaster.

    I had some older repairs in the ceiling that was just done with drywall mud and of course, it wouldn’t hold so we chipped out the old repair and filled that with a scratch mix.

    I repaired the bad areas will Big Wally’s Plaster repair and I was really happy with it. John is hand mixing the lime putty and adding sand when he is ready to apply it. He made up his batches of lime putty weeks in advance and stores it in 5 gallon Menards buckets with about an inch of water on top. It can store like that until you are ready to use it.

    Check out his work at the link below. He may come out and give you a class if you need it. He is in St. Joseph now.

    • Bummer, Blair. I need that information too.

      Ross, this post couldn’t be more timely. I need plaster work done in my bedroom due to a contractor who did shoddy roof work. The water leaked through the attic and caused cracks and holes in my bedroom. I didn’t know until I was awoken with a dripping sound. Believe me, I was livid. His response? “Oh, I’m sure it’s a simple roof fix”. He told me he could re-drywall my bedroom. I stated that I have plaster, I want plaster repair. Well, about a week later, he stated that he can’t find anybody to do plaster repair. So since September I have been looking at the cracks and wondering how to repair it. Meanwhile yesterday I got an invoice from him for the rest of the work, which I consider the job not complete.
      Now I have some information to share with him about how to do it. Thanks Ross! Your blog is not only entertaining, but educational as well.
      I will suggest both Old Town Home blog and Master of Plaster company to him. Perhaps we don’t have to end up in court.

      • You could find someone who repairs plaster yourself. Deduct the repair cost from the invoice amount and pay that after making sure that the roof doesn’t leak.

  5. Hello, Ross from Germany,

    You know that we have radiators nearly in every house, but no one cares about mixing plaster and sheetrock together even in the same room! e.g. in our diningroom:2 walls sheetrock, 2 walls plaster.

    Heating with convection isn’t as comfortable (draughts!) than with radiation (warming the surrounding things). Your radiators emit the heat 70% as convection and only 30% as radiation (for e.g. heating the walls…)

    So I think plaster or sheetrock is not important!

  6. Hey Ross!!
    Love the blog. Love everything you’re doing. Love the house, I wish I had the everything to fix up some of the old houses in my area. Keep it up, we’re all cheering for you.
    I read a number of blogs about people fixin’ up houses and this post about plaster made me think of Wendy and Alex over at Old Town Home (dot com). Alex seems to be particularly meticulous about the way he does things and they’re doing a bunch of plaster repair at their house. Maybe there’ll be some tips he knows that might help you out.

    Good luck!!

  7. So I guess im ignorant on this plaster stuff ….. isn’t plaster just a mix of cement (white or standard) nixed some sand, lime etc???
    I know they just plastered my pool with white marble dust, mixed with white cement etc……. stuck great

    • Modern plaster has very different components than traditional plaster, so it’s important to use similar ingredients to the original plaster. It’s the same with mortar for brick walls. Old mortar had much less cement and was much softer than modern mortar formulas. If you have an old brick house and use modern mortar with the old bricks, the mortar will be harder than the bricks and the bricks will start to crumble due to expansion and contraction.

    • There are several types of plaster and they are used for different things.

      Your pool was most likely a portland based plaster similar to what is commonly called stucco. Often this is a 3:1 Portland:sand mix but ratio can vary depending on the application.

      Many old homes used lime based plaster inside and out which has many advantages but is often more expensive and depending on the requirements may not be the right product because it is a ‘softer’ plaster. Because it is differ it does handle movement much better than the very hard but brittle portland based players. Autoclaved lime can be mixed with sand and keens cement to make a very nice sand finish that can be floated with an open cell cellulose sponge to create a beautiful finish that refracts light wonderfully. No need for paint if you want a bright white ceiling. Authentic Venetian Plasters are lime based as well as fresco style paintings. (Think Sistine Chapel)

      Finally there is Gypsum Plasters. These are your common interior plasters. This type of plaster is not recommended for exterior application but works great inside.

      You can mix and match but you have to go from strong to weak with your layers.

      Hope that helps clarify things.

  8. man who would think its so complicated? but that does make sense! Didnt hat also add aminal hair in it to help bond it together?

  9. The old plaster probably had horse hair mixed in, as was commonly done- are you going to mix some cat hair into your new plaster? Then it’ll really be a cat-guy’s house 🙂
    Just a (weird) thought

    • On a curved wall such as in a round tower, one uses the taping knife in a horizontal direction, which is not curved. The easiest mistake to make is to apply the brown coat so that it is flush with the finished walls. They should leave some room for the finish coats to fill without being so thick that the finish coat cracks and has areas which sink as they dry. Using finish coat to fill a hole results in uneven drying and deep cracks at best. After trying this multiple times when I was younger, I learned.

  10. Hello Ross, George here, the fellow with the long winded plaster related post back in April of 2017. I am delighted you are pursuing this route (misery loves company!). If I may, I would just like to reiterate a few points. Structo-lite is terrific, it is light weight and I thought a delight to use. And I used a lot of it. It is very important for anyone reading your blog and undertaking this to comprehend how thick 19th century plaster walls are and just how many bags of material are necessary for a sizable job.

    Owing to the fact that I was going to refinish my floors, I didn’t do a terrific job of initially protecting them and the Structo-lite that fell on unprotected boards left permanent stains. Plaster Weld is absolutely essential for a secure bond to the lath and I found in a brief cost cutting measure where I used a different bonding agent, that the Plaster Weld had the additional benefit of preventing an ugly tobacco brown color staining from appearing in the plaster after the wet material made contact with the lath. This required additional coats of primer to sufficiently mask.

    Two years after having plastered I have very few cracks and I attribute this to having used mesh. My house is now a traditional Bed and Breakfast and since guests frequently comment on my extensive use of picture rail moulding, inevitably the topic of plaster comes up and the story of my trials with it, and the finished appearance, generate a lot of compliments. Best of luck with your walls.

  11. Thanks for being so conscientious about the repair of your walls… it’s going to look great and you’ll have fun learning a new skill!

    Here’s a link to a manual for plasterers from 1879; it’s a bit older than the Cross House, but techniques in the 1890’s hadn’t changed much from those shown in the book – it might be of help when you run into questions:

    Adding pure latex or latex paint to the mix in lieu of water can assist adhesion in some situations. Try experimenting in an inconspicuous area on a flat wall before tacking the curved walls of the tower… you’ll be a pro in no time! I’m doing some small plaster repairs on a project right now and have had luck making my own version of a base coat by adding sand to joint compound… it helps to prevent thick coats from cracking as they dry. It also helps to mist or dampen the lath before you apply the plaster. Looking forward to seeing your progress!

  12. I know you are a hard worker from reading all your posts and seeing the results but there’s a difference between working hard and doing hard work easily. I am also a hard worker and in summer work 5 days a week gardening for folks and 2 days a week selling at flea markets (and if you don’t think this is hard work, you’ve never done it) and evenings selling online (ps – I am 73) but the two things that makes my jobs easier that you don’t seem to posess are a huge garden cart for moving stuff outside (like plaster from car to house) and a really good dolly (with air filled tires) fir moving heavy stuff in and out. I can pull 200# up stairs with a dolly easily or 5 bags of plaster for example. less work less trips less time wasted. more time to pat kitties.

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