I do think when archaeologists are doing that they should be into
walls. I worked on some backyard disturbance of the Captain Brewster
Hawkins House in Setauket, NY, a shipbuilder, chandler, who restarted
shipbuilding industry there, built "Wanderer" a luxury yacht, (and
others) sold it to a Louisiana cotton merchants agent in 1858, after
his son Thomas captained it for a year. It was then outfitted with
water tanks in Port Jefferson and reported to have been boarded by a
British "slavery blockade" officer off the coast of Africa. It picked
up 600 Africans, 400 survivors landed at Jekyll Island, Georgia in
1859. One of the walls upstairs, had some graffiti "Down with Popery"
which was interesting.  Lately I've been thinking the water tanks were
also mixed with maple "sirup" (early 20th century spelling in a NY
State Agricultural manual).

I have also seen the paint section for reconstruction of the so-called
"Tweed Courthouse" (NYC completed by Mayor Fernando Wood) before it
was to be a museum of the City, instead of the current mayor ordered
Dept. of Education headquarters. Quite a few coats there. Another wall
of the old Congregational church whose Stockaders I used to camp with
as a tyrol, had the pencil marks of the carpenters, where they did
their math. Interestingly, from Setauket, they built it with some of
the techniques of shipbuilding.