How To Repair Plaster Walls and Ceilings

Learning how to repair plaster walls and ceilings isn't as hard as you think. But it isn't like drywall and uses very different techniques and materials.

Materials needed:

Don't use straight plaster of Paris. It will set up before you can get it out of the bucket. Use Durabond 90 instead. It's a plaster of Paris based product with premixed retardant. It will give you around an hour of working time. Use general purpose sand for your 1st and 2nd layers. Metal lath and plaster bonder are the two other things you'll need.

Plaster construction has two parts, the foundation called lath, and the plaster that is spread through it and on top of it.

Lath nowadays is metal screen-like material but earlier construction is thin strips of wood. In both cases the lath is fastened to the ceiling joists or wall studs. When repairing or restoring a plaster surface it's important that the lath is secure and sound.

Plaster can be gypsum or lime based or even a mix of the two. Lime plaster is the oldest type, made by burning limestone in a kiln. The resulting lime is used for plastering and for cement. Gypsum plaster, known as plaster of Paris is also made by heating in a kiln.

Lime plaster is the superior choice especially for kitchens and baths but it's much harder to work with. For general interior work gypsum based materials are a better choice for amateurs.

Plastering is usually done in 2 or 3 coats. You can spread the coats out over a few days or even do them all on the same day. The existing plaster and lath needs to be slightly damp. Each coat of new plaster should be misted with a squirt bottle before the next coat is applied as well.

The first coat, called the scratch coat, is a mixture of sand and plaster. In older homes it often had horse hair or other fibres to help it stick to the lath. Applying the scratch coat is tricky. The plaster is more or less squeezed through the holes or gaps in the lath. Lots of it can end up on the floor or on your head.

The second coat goes on much easier as most of the holes and gaps in the lath will already be filled in. This coat is a mix of sand and plaster as well. This coat should sit a bit below the final surface to leave room for the finish coat.

The finish coat is straight plaster. It should be fairly thin, perhaps a ¼ inch or so. Before laying this coat it's a good idea to scrape down any areas of existing plaster that have sand stuck to them. You can see me do this with the edge of my float in the video several times. Doing this will keep sand out of the finish coat. Hopefully you can get a nice smooth surface with your trowel on your first attempt. Doing so will save you a lot of very difficult sanding once everything is hard and dry.

Andrew Shackleton, Broker

Royal LePage Wolle Realty

519 578 7300
226 600 1548

[Clothigami]

This is the best instructional video I’ve watched on repair my old plaster walls thank you

[johnjohn-nefw]

What a great informative video. Thank you!

[bamnjphoto]

I'm glad to come across this video. I just had some rewiring done and needed to patch some plaster wall and ceiling holes this video was very helpful.

[nickmulcahy]

Andrew Shackleton does what nobody else on Youtube DIY video does -- that I have seen -- with regard to plaster ceiling repair: he shows you a tough job. I noticed that the other DIY videos all have plaster "bubbles" or sections of ceiling that bowed out and need to be pried away and repaired/filled in with drywall. The repair is relatively easy. There are not three coats of plaster and related products. There is one coat of "mud." He also follows up with all of the comments made here. Nice work from Andrew.

[oskarbjornstad]

That works. There’s also a product USG makes called structo-lite that’s designed as a modern day base coat for plaster so u don’t have to mix and sand. Can finish over it with any material u design or use a float to finish with it

[turtlebuster]

Excellent thanks for making this video

[peterhewel]

Walls, Type S mortar with accelerant to speed setting. If have metal lathe it is easy. Ceilings? Originally it was generally mortar similar to modern TypeS. Waaaay cheaper than Durabond . 60 lbs sack is under $5. Around here, only Sika type R adhesive. Pressing it into the ceiling lathe is tough. I might try Durabond 20.

[rebicul]

Thank you for the information! I have a similar repair. If the sides of the lathe are clear of plaster, do you recommend removing the insulation and pieces of plaster from the attic that are stuck above the lathe?

[silverlocomotive]

Why didn’t you remove the plaster between the lathe? Isn’t the plaster supposed to get pushed up through the lathe and mushroom over the top side to give it holding strength?

[HafMpty]

I’m getting ready to fix some holes in my house from a knob & tube removal and replacement job. Will I need to cut out more of the plaster to expose more lathe to attach the metal lathe to? Also, based on the comments would you still do your repair the same way or would you do a finish coat with easy sand or some of the premixed joint compound? Thank you for this video BTW. Super helpful.

[CroSensate]

Just saw this video. I have a home that’s about 95 years old so a lot of plaster in the house. Anyway, the back bedroom has two windows and the wall around it is roughly original plaster but I can see that roughly half the plaster is damaged or covered up with 1/4” Sheetrock. The sheetrock is mostly by the left window so the wall isn too even bc of this. Haha I ripped out the baseboard yesterday and the plaster above it is pretty mangled. A lot of it crumbled under the baseboard so I want to repair it. Would you nail in the metal lathe on top of the brick and then out cement on top of it? Would you then do a straight durabond mix and put it on top or mix durabond with sand like you did in the video? Any feedback would be highly appreciated.

[wyattsdad]

That doesn’t look like what plasterers use. I don’t think they’d use dura-bond. They use a product called structolite first, then they use plaster. But I’m curious if this held up.
How did it look once painted?

[Titantitan]

I don’t think you really need to use the sand for interior but I’m not expert. But I’d also use 20 and not 90. Stuff dries hard as a rock.

[insantiago]

The big corporate companies are going to hate me after I make this comment but who cares, Never use durabond for interior walls that stuff doesn’t sand when dry and it cracks leaving hair lines on the outside edge when the house moves because it’s cementious and cement doesn’t contract and expand, if you use it at least use it for the correct application, if your making house repairs use plaster of Paris it has lime in it that withstands moisture and repairs itself when wet it sands unlike durabond but is harder than joint compound, if your using joint compound around showers or sinks don’t do it because the compound will bubble and blister it’s water soluble meaning anything that it comes in contact with that is wet or moist can dissolve it, plaster of Paris on the other hand is your best friend when it comes to interior repairs it’s the reason all the tall cathedrals in Europe are still standing after hundreds of years of weather changes.

[dollyhamilton]

Would have liked to have seen from the very beginning layer to the last layer, not just everything in between. Still helpful. Thank you.

[patstonecipher]

It would be Nice if you would show step by step in video

[ronbessant]

You people sure do things the hard way 🤨🤨