Here in New England modern pine trim and siding starts to rot in about eight years if there is any sapwood. I am convinced most old pine is more rot resistant than new pine but no one has been able to definitively tell me why.

Being 18" from the ground is a great design detail for durability with any species.

If you are talking board and batten material applied to a timber frame, be aware that with only one layer of material it is difficult to properly flash window and door openings.

Fine Homebuilding has a short article on installing and finishing b&b at: http://www.finehomebuilding.com/item/29146/how-to-install-board-and-batten-siding

In the 19th century it was recommended to relieve the back side of the battens so the edges fit tightly which helps keep water out, b&b siding leaks more than materials that lap such as shingles and clapboards.

Good luck;
Jim

The closer you look the more you see.
"Heavy timber framing is not a lost art" Fred Hodgson, 1909