>My trees/logs are Douglas Fir. Will they last in such a wall?
FWIW, Douglas Fir is used in planking wooden boats so it should not rot
too fast. But untreated it will eventually rot. You need redwood or
cypress or locust for long term ground contact. Heart pine from the South
is also very rot resistant but will burn even in the rain. What is your
design life expectation? or is recycling downed logs more important? Mike
Miller