Patching and Plastering - How would YOU do this...replacing wall sections

The electricians in bldg complex are removing 1 1/2 foot wide floor to ceiling section in 90 year old plaster over wood lath in many units. This is definately a creative fix as there is not much clearance behind the wood lath. From brick (interior wall separating units) wall to finished surface of plaster is 1 3/4". To complicate matters, the new conduit runs from floor to ceiling. Somehow I will figure out how to get wood supports back there. Once I do that, do you think drywall is the way to go? Will joint compound or easy sand adhere well to the adjoining plaster? These are very long hallways so it is not economically feasible to skim coat the entire area. The goal here is to get the new wall sections flush as close as possible and complete by mudding/taping. Is there a better way? I have read somewhere to use blueboard and a veneer plaster finish. Is this overkill for people who can't spend too much.

Also, for smaller manageble holes I have used plaster of paris to get a quick drying back base and it turned out pretty decent. I then used a little joint compound to smooth and feather it out. Is there something wrong doing it this way? Do you have to tape for small holes?

Thank you for reading this far.

I know drywall [not plaster] and would shim it out to just under the level of the plaster finish and use durabond or easysand. J/C should be ok for the final coat. It won't be an easy job to make these repairs invisible on a long wall.

Our plaster pro should be along shortly and can give you better info.

To what is the lath attached now? Are the electricians removing a stud or some other framing or furring member?
Is there a support for the existing lath on eather side of the opening?
Do you have your heart set on drywall?
I would find it faster to plaster than to drywall but that's just me.
If you want to know how to plaster it, start by answering these questions and then search the archives. I have posted numerous times about how to plaster. I'm too tired to do it right now.

Plaster to horizontal wood lath to vertical furring strips attached to brick. The electricians cut where they had to cut, not being too concerned if it was near a framing member. So, basically you are staring at a huge floor to ceiling rectangle with brick. The new electrical conduit will get in the way of any kind of horizontal supports. This cut did compromise the stability of the plaster lath on either side as it is just ' free hanging'. I would have to insert furring strips from behind to stabilize the 'free hanging' sides. The furring strips would have to shimed out as someone said and choose a thickness of drywall to get it all flush. Drywall is what I have dealt with in the past. Will it stick to plaster (painted walls ). I just didn't know if there would be some kind of bad chemical reaction. I've only used plaster of paris for small repairs.

So will the conduit project through the finished wall? Is there room to put drywall and not have it bulge over the conduit?

Were it mine this is what I would do: Break the plaster back to the stud or furring strip or whatever on each side. Donth worry too much about the lath. If it stays, fine. Then I would attach 3.4 metal lath to the studs bridging the gap. Now this might be a longer than preferred span for the metal lath but maybe you can add some support at a convenient place. Then plaster. Or if this is a lot of patches hire a plasterer. I think it would actually be faster to plaster than to drywall but that's just me.

the conduit is just barely below the underside of horizontal wood lath. It is very close. Electricians attached conduit to the brick. I do believe plaster would be faster as there is no repeated coats of mud over tape etc. Just curious about the metal lath...what is the spacing requirement of studs (furring strips) to properly secure metal lath. This raises on option that I will discuss with the building. Maybe we can set things up for a plasterer to come in. In your opinion tightcoat would it be less costly to hire out a plasterer verses drywall guys. Thanks

Go here to see a chart.

http://files.buildsite.com/dbderived-f/clarksteel/derived_files/derived157112.pdf

A sheet of 3.4 metal lath is about the same price as a piece of 1/2" 8' drywall but only about half the size effectively. I would think it would be faster to nail up lath that to cut and fit drywall. There is a right and a wrong side to lath. I guess there is to drywall also but it is less obvious with lath. Then I think it would be faster to scratch, brown and finish the plaster than to tape, recoat, recoat drywall and make it fit the plaster it will either be too high or too low,either way will take some filling in. And if you allow for adding support for drywall and not for plaster that will probably about offset the difference in the cost of the plaster vs. drywall mud. You might be tempted to try to drywall it yourself. I think an amateur could actually plaster faster until it comes time to finish. Are the walls smooth. That's an easy finish only thing is the material is not very amateur friendly, Still you should be able to handle a patch that small if you just do one at a time. How many of these are there?

Can you put a photo somewhere we can look at it? That would help a lot.

Now you ask about different trades: Well, I'm a faster plasterer than I am a drywaller and I know all ( at least most, I invented some of them) of the tricks to patching plaster. My experience is it's easier to patch plaster with plaster than with drywall. I think the drywallers here disagree.

There must be dozens of posts here about how to patch the plaster. Search for them and read them then ask more questions if you have them.

Here are some pictures and as you can see I don't have much clearance to add supports on the left side to attach drywall. I don't think I cant cut the wood lath off the supports to provide a nailing surface for drywall as what will be holding the wood lath? I read your earlier post to homewrecker 'appreciation of plasterers' and kinda have a more understanding of plaster. Thanks for all your input



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I was at the hardware that bldg. has account at and found that they carry structo-lite....it said just add water...if you add sand as you mentioned in an earlier post -, will that improve workability or performance? Will regular sand be ok or specialized sand? They only had one kind of metal lath 4 x 8 sheet diamond shaped and the guy said you can hang it vertically or horiz. I really would like to try plaster but it seems intimidating. I have a week to decide what I will do regarding this large section.

Oh can you answer this. I will be patching up perimeter holes around swichplates and outlets tomorrow about 10 of them). The majority of the walls are plaster with some drywall (newer remodeling)Do you think I should use plaster weld (bonding) on the edges of old plaster or will P of P stick to it ok. Most of them just need about a 1/2 - 1 inch fill. I'm curious why you don't need to apply paper tape at the seams of plaster repairs.

Thanks, for any info

I am visiting my parents who have only a dile up modem on very old POTS wires so the pictures loaded very slowly. I only looked at three but I think I've seen enough.
Wood lath are 4' long. ABout every seven lath the joints are staggered, that is set over one stud. So some of the lath might end at a stud and some wont. The ones that don't will still be held on the other end. What I wanted you to do is break the plaster over to the midddle of the stud each side of the opening. You don't mess with the lath. Then nail or screw(I like screws because they shake less other plaster loose but they are slower) metal lath to the studs. I have never seen metal lath in the dimensions you descibe. What you want is diamond mesh which has holes about 3/8" X 1/2". If that is what it looks like the size is imaterial It does indeed matter which way it goes. Never vertically and when you rub your hand against it it should have more friction going up than going down. If it is wrong then flip it end for end. Then study the lath and you will see that there is a difference.

Now about Structolite: That is fine. Mix it to a consistency of about oatmeal
If that isn't right you can add more water or more Structolite. Now you don't need sand for it but a callon of sand to a 50# bag will help it set. Structolite is notoriously slow setting and it tends to dry out before it sets. There are other ways to get it to set. I think a galon of plain sand is best. Scratch it. Let that set. Then brown it. That is the second coat where you try to fill it out flush with the adjacent plaster then just screed it off even with the adjacent plaster then cut it back 1/16" to allow for the finish coat. Or maybe better for and amteur is leave it even then finish it with a coat or two of joint mud.
Paint the edjes of the existing plaster with a bonding agent.
The reason you don't neet tape on narrow places like the boxes is because plaster is harder and stronger than joint mud. It would nt hurt to fill them with plaster but a setting type of joint mud to fill them flush then a laer of tape and joint mud might be better.

I just may decide to take this on

You can try a couple and see how it goes then decide. If you do this a couple more words of advice:
1 Use a bonding agent on the edges of the existing plaster
2 Keep the existing plaster clean. You don't want to feather the new plaster onto the existing plaster. Now if you finish it with joint compound it can feather but if you elect to use plaster to finish it keep it all clean all around and when you are done you will not be able to detect where the old and new end and beging--if it is a smooth wall and once it's painted. Now if you try a couple you will probably he more questions so ask away. This is doable by a brave amateur.