"Cash" wrote in
:

Give the frame a chance and give it five coats of good quality paint
(rather than 'tinted preservative) [1] - and also keep the frame about
20mm up off the floor to prevent the end grain (probably untreated
anyway) from 'sucking up' rain water off the floor.

I did think of that (raising it off the floor). I probably should have
painted the frame on all faces before fixing to the wall too, but I didn't.

[1] Prepare the timber properly and give it the following:

1 - Coat of aluminium base primer (or similar)
2 - Coats of oil based undercoat
2 - coats of oil based gloss

I was thinking of leaving the door and frame unpainted for the whole of
this summer, and then painting it all, in September, after it has become
well dried out and seasoned. Would you condone that idea? It's West-facing,
by the way.

Al