I'm replacing a shed door. Nothing fancy and I didn't want to spend a lot, so I didn't invest a lot on an exterior door.
Instead, I have a hollow core wood door blank to which I've applied two coats of primer and one coat (so far) of exterior flat paint.
While it's not a huge deal if the door only lasts a few years, I'd like to do whatever I can to prolong its life as much as possible. What further treatment can I give the door to help extend its life?