On Sun, 11 Jan 2004 05:55:09 GMT, Fitch R. Williams
wrote:

Make it bigger than you think you will need
and a FLAT surface under the door so you have nothing to roll over.

I was showing an inch drop - that is probably a mistake. I'll adjust
the drawing.
That inch (between the inside floor and the outside) stops rain
blowing under the garage door. Depends on how exposed it is, it would
be easy enough to make a shallow ramp.
Geoff