"Mark" wrote in message
...
Looks like plaster over sheetrock lath or drywall. The thin top coat is
either the finish skim-coat that gives the surface a smooth finish, or a
thick texture paint, can't really tell from the picture, but if it is soft
and flexible it is probably paint. Stiff and brittle it's a skim coat.

It's stiff and brittle, but a skim coat over the entire wall board?

I have removed a section of the soffit and now need to patch a two feet
strip all the way across the top of the wall and ceiling. I don't know if
regular sheet rock will match, I will have to try 3/8" sheet rock and try to
match it I hope the thickness will be even.

Thanks,