Walls

 If you are building an addition to your house then you are almost
certainly going to cover the walls with Sheetrock. (wallboard,
gypsum board) It is called many names but they are all the same
product.

I come from an era when houses were built with plaster
walls. There are many thousands of people who will still insist
"they don't build houses today like they used to with those solid
plaster walls". Well as far as i am concerned, that's good. They
cracked & peeled & bulged & were very expensive to build. The
good old days aren't always what they were supposed to be.

Virtually all home building was stopped from 1941-1946 because
of the war & a shortage of materials & labor. It was then that
someone was bright enough to paste some paper on both sides
of some plaster like material. They then could be installed in large
sheets on walls & ceilings. It took less labor & did a better job of
smoothing out the wall. The was a problem was finding people to
spackle the seams & that was solved with the left over plasterers
who then taught their children.

Ceiling moldings disappeared when they figured out how to spackle the large gaps between the wall & ceiling.

Along came wood paneling & then artificial wood paneling & cork
paneling etc. & the walls were covered for years with this stuff.
The fad wore off & now it is pretty much paint & wallpaper.
If by chance you are going to use paneling, then don't bother with
the spackling, & save the cost. Some of my customers had me
panel over the studs & saved the cost of the sheetrock & the
spackling.