Walls and Ceilings - Is it plaster?

All the dry wall in my house seems to have a consistant layer exactly 1/8 inch think on it. I had to cut out a bunch of wall in the basement and when I put the new wallboard in it was 1/8 inch lower then the rest. I did my best to fill it with mud, but it is not perfect. Looks like a shadow all across the wall.

So, is that a layer of plaster that they put over the entire wall? If so, why?

Should I have covered the whole patch of new board with plaster?

Looking to make sure I do it right next time!

Thanks.

It could be. I've seen some houses that had the "first" drywall installed from the 40's and 50's which was in 2' wide sheets hung horizontally which they put up and plastered over with a thin layer as you described. Sounds to me like you need to apply more mud using a wider knife. Next time, you could shim your drywall out 1/8" or better yet, use drywall that's the right thickness. (5/8 perhaps).

Well the house is only 10 years old and from what I hear from everyone with newer houses, this is how they are all done. Maybe it gives a better surface to paint?

As for the thicker sheetrock, I did try the 5/8 first. Funny, using that made it stick out slightly. I'm not sure why. That seemed harder to feather in properly, so I went with the thinner stuff.

Most plaster houses built over the last 30+yrs have blue board [a type of drywall] and then are plastered over. Easier and cheaper than the old lath type plaster.