Plaster separated from wall. Any help would be appreciated.

I've been trying to figure out what I need to properly repair this wall and it is pretty confusing. It looks like a top layer has separated from a bottom layer. I've read that I might need something called PVA so the new top layer will adhere to the bottom layer. But again I don't know much about plastering and as much as I would like to just pay a professional to do the job, I don't have the extra money and it is a pretty small job. The area in need of repair is about 1ft(H)x6in(W). If someone could list the materials I would need and maybe a quick run down of the process that would be great!

 

Plastered walls generally consist of a rough coat first and a finish coat second. The first coat is held mechanically to the wall by first attaching plaster lath or screening to the wall studs. The second coat, much thinner, cements to the first coat. Approach to repairing would be different based on screening or plaster lath beneath the plaster. What do you have?

 

 

How old is the house? The picture looks like you have gypsum plaster with what we call in the trade whitecoat finish. Sometimes because they are somewhat different materials the finish looses it bond to the base coat. This is a simple fix using amateur friendly, easily available material. Maybe a PVA bonding agent would help. I always have some on hand so I would use it. I don't know if it's so essential that you need to buy some. Clean that plaster well no matter what. A stiff brush or gentle wire brushing is good.
First scrape off any additional finish that is loose. You could probably scrape the whole wall off. That is not necessary. You have to decide when it seems sound enough to stop scraping..
Second treat that crack. I would embed some FibaFuse tape over the crack with drywall joint compound and let it dry. Were I doing this I would use a setting type of joint compound. It sets quickly and you can recoat as soon as it sets, it doesn't have to dry. Third then spread some of the same material you use to embed the tape and fill it flush with the surrounding surface. If you need to do this in two coats let the first coat dry if you use ordinary joint mud or let is set if you use quickset and give it another coat and sand it off smooth. Now the picture looks like there is a texture of some sort but I can't see it well enough to tell you how to do it.
We can help you with the texture if you show us a good sharp picture. Then prime and paint.

 

The house is pretty old I think it was built in the 20's or 30's. I got some fibra tape today. Gonna try and tackle the project tomorrow. Thanks for your help I'll keep you posted on how it goes!

 

There is a big difference between Fiba tape and FibaFuse tape. Fiba tape is just a run of the mill sticky tape. Most of us prefer FibaFuse which is a mesh tape that must be embedded in joint compound.

 

The fiba tape I got also says it should be embedded in joint compound. And it is a mesh style tape. I think it will be fine.
The brand is "ADFORS FibaTape Original"