As a volunteer with an organization that does free will home repair for low income elderly homeowners, I often am called upon to repair ceiling plaster that has opened up because of water damage.

Our crew is not professional and we work with limited resources and we work on dozens of homes in a year's time. My point is that we usually spend no more than a few days and less than $100 to patch up the plaster.

That being "said", I'll use todays's work as an example of what we do.
A small section of plaster (2' x 1') was damaged on a ceiling. The laths were showing. We decided to use 1/2" drywall and blend it with the existing ceiling. The easiest(?) way we knew to do this was to draw a rectangle on the ceiling, score the lines to limit the plaster affected and then chisel out the old plaster. Today we were just doing demolition work. The next time we visit that house we'll attach a drywall patch to the laths and tape and mud. The laths were in good shape and we'll be using drywall screws to secure the drywall.

That's our quick and dirty solution. Since we won't be going back to that house to see what our patch looks like 6 month or more from now I'm open to any predictions a reader might offer as to it's durability.

I know that we are capable of restoring the plaster with several coats of compound over a period of days but we don't usually have that kind of time to invest in one house.

Now comes my question. The hardest part of this endeavor was actually scoring the old plaster in order to limit the amount we removed. We're working overhead with a multitool and the blade gets chewed up fairly quickly. We're trying to avoid using hammer and chisel for fear of pulling more plaster down than we care to.

I've Googled "removing plaster from laths" and it seems the answers all assume you take them both out together which is not what we want to do. Any suggestions, please?

Old Al

 

A diamond blade for your multitool like this does a pretty good job cutting the plaster without loosening the other surrounding material. However with water damage most bets are off. A diamond blade in a angle grinder also does a good job but this can be VERY dusty so running a shop vac is a must.

While the sheetrock method you are using is a good one, and will last a long time, another option is to just coat it with STRUCTO-LITE made by USG. I have used it and it is a very fast setting (however you do not want to sand it) and sets up hard. I have put 3-5 think coats in about 3 hrs. It also has a rough texture similar to plaster but is much lighter. A bag is about $20.

Another option is a combination of the two. Cut your rock short and fill the rest with the structo lite

 

Next time, tape some .75 mil painters plastic up to the ceiling around the repair, and make yourself a little "shower curtain-like" area to work in, so that dust can't escape.

On a small amount of demo, I'd also use a 4 1/2" grinder and a diamond blade to make the cut. Hold a shop vac up as you are making the cut to suck up some of the dust. You'll need a respirator, or at least a good n-95 or n-100 dust mask.

 

I've always used drywall coupled with a setting compound like durabond to make those types of repairs to plaster. Durabond dries faster and harder than regular joint compound, you'll want to limit any unnecessary sanding! It's a good plaster substitute for those of us not well versed in plaster work
The drywall should be screwed to the joists not the lath.

almost forgot welcome to the forums Al!

 

Thanks so much for the very good advice! I've not seen STRUCTO-LITE but I'll be looking for it at Home Depot and Lowes. I've had some luck with a white polymer flooring plaster.
It sticks to anything and resists sanding also. It's not fast setting which actually is helpful for a novice like me. I've used it as an adhesive to bond sheet rock to a brick wall (interior surface) when studding out was impractical. How does the STRUCTO-LITE compare to plaster of paris? I'll look for a diamond blade for my Craftsman multitool. It's not a heavy duty tool but I use it sparingly so it serves.
Thanks for the encouraging words about the likely endurance of the materials I (okay, WE) use!

Al

 

Thanks for the Durabond suggestion! We use the joists when they are in the work site,
and always when there's any significant amount of drywall being attached.

Al
Ps This is definitely a good place for me to be!

 

I'll check out the cost of grinder wheel (which we've got) and multitool blades. At times I've used a Bosch rotary tool with carbide bit. Talk about stirring up some plaster dust!
Another tool that's served us very well is the Capstick 3rd Hand pole. If I can get the office to buy us another pair we can set up that shower curtain and perhaps even use
the same pole to hold a vacuum hose against the ceiling close to the work.

The responses I'm getting here are getting the creative (and penny pinching) juices flowing.
Thanks, again!

Al

 

I can't really compare STRUCTO-LITE to plaster of paris do to my limited use of the latter. I seam to remember plaster of paris being much smoother where structo-lite has a bunch of grit in it giving it a thick body.

You may have a hard time finding it a the big box stores. I find it is only stocked in locations where lath and plaster houses is the norm in the neighborhood. You may have to go to a drywall supplier.

 

All this talk about grinding, cutting and dust makes me think there must be a better way. I would plaster it. Use metal lath or chicken wire over the wood lath. Screw it to the joists and wire tie it to the lath where there are no joists. Pull off what comes off by hand, cut the lath or wire to fit and plaster it with Structo-Lite. My experience with Stucto-Lite is that it is extremely slow setting -- to the point of drying before it sets and remaining chalky and soft. There are a lot of ways to get plaster to set: Some Portland cement, some lime which also helps it trowel down smooth, some sand in the mix, some raw gypsum or old, set plaster in the mix, alum in the mixing water, etc.
Plaster always fits the shape of the hole and preserves the fabric of the rest of the house. I can actually plaster a patch 2' "square" or round for that matter faster than I can put in drywall and leave it presentable. It is not that complicated.
On lids plaster is often less than 1/2" thick from the face of the lath. 1/2" drywall is frequently too thick.

Now I suppose to these low income elderly people, anything looks better than a hole in the ceiling but why not do it better and give them a patch that doesn't look like a patch?

 

That makes a lot of sense to me. I see myself using drywall screws and dryw washers to secure the metal lath. I'll try that on the next suitable job. I'd rather mix a dry compound than squint through the dust and sweat.

Al