Walls and Ceilings - Replacing sections of plaster wall

In a recent post, I had asked about how I should go about replacing what I thought was double-layer drywall in my kitchen. After further investigation, I discovered that I wasn't dealing with double-layer drywall. What I've actually got is a plaster wall with a gypsum lath backing: 3/8"-thick gypsum lath (16" x 48" boards nailed to the studs horizontally) with 3/8"-thick layer of grey plaster underneath a 1/8" white veneer plaster.

How should I go about replacing these plaster walls? I'm mostly concerned about what to do where the existing plaster walls will meet the replacement walls (an outside corner and a section of wall in common) Should we hang a double-layer of blueboard and have a professional plasterer finish things off? Or will drywall look okay? What do we do at the junctions where existing plaster meets the new drywall (ceiling, outside corners, common wall)?

Any advice is greatly appreciated.

Are the replacement walls going to be plaster? If so I think I would do it like this: It takes some care but the plaster can be broken back on the existing wall about 3". This will allow room for a corner bead. Then use one thickness only of blue board and plaster it like it is now. The only difference is the thickness and dimensions of the lath (blueboard). When a wall continues do it in plaster. Again the blue board is a little thicker so the plaster will be a little thinner. Make the plaster extra strong since it is thinner. Where existing plaster meets new drywall you might have to repair the plaster so it is all flush with the remaining then drywall up to it and tape the angles as if you were taping drywall to drywall. Corners are a little trickier. One idea is to put up a temporary ground like a 1X4 at a corner and plaster to it then install a drywall corner bead and tape it as if both sides were drywall. You can perhaps install the cornerbead after the brown coat but before the finish coat and have a straigher wall that way.

I don't know if you understand what I am talking about but I can picture it and I think any plasterer could too.

Another option is to fill any voids in the walls with plaster and screed them flush with the existing then drywall right over them.

How much wall is being replaced relative to left in place?

As to whether or not the replacement walls are going to be plaster: I don't know. That's why I posted. I'm replacing one of the short walls and 1/2 of one of the long walls in the kitchen where our new cabinetry is going. We gouged the walls pretty good when we removed the old cabinets and there are some electrical changes we'd like to make so I just decided to rip out the walls in that section completely.

Since we'll be installing cabinetry, appliances, and a tile backsplash against the walls that I'm replacing, ideally I'd just like to hang drywall, tape, mud, and sand to save the expense of hiring a professional to do a full blueboard/veneer plaster job on walls that are going to be mostly obscured anyway. However, my biggest concern is how to get the thickness of the old walls and new walls to match and how much skill would be required to make the junction between the old wall sections and new wall sections (as well as the junction between the new walls and the plaster ceiling) look decent.

From what you've said, hiring a professional plasterer might be the way to go since I don't feel comfortable doing anything more than taping, mudding, and sanding away my amateur sloppiness. :)

Since this area is to be mostly covered with cabinets, I'd add shims to the studs so that either 1/2" or 5/8" drywall will fill in and flush out pretty closely to the existing walls, then tape & mud to smooth it out. You just have to remember to apply your mud in thin layers to prevent cracking. Just my .02¢, follow tightcoat's advice concerning plaster work. Depending on where you're located, you might find it somewhat difficult to locate a plasterman willing to take on a small job such as this. Hope that helps a little anyway.

If you decide to rock it and shim it out close to flush keep it below flush just a little. It's easier, IMO, to fill drywall to the level of existing plaster than it is to fill plaster with joint mud to drywall that is high.
If you do it this way use setting materials. You can do multiple coats in a day. As soon as one coat has set you can give it another coat. Let it dry completely before sanding.