If you use concrete piers for a deck or porch, it is best to slope the edges to help water drain away. We used to do this when posts were set in the concrete to keep the wood drier. Now it is still a good idea to keep the metal post base from losing the zinc coating and rusting out. The only flat spot on the pier is the center where the post base will rest.
Piers Should Have Sloped Shoulders
Brian Campbell, Basswood Artisan Carpentry Professional Saint Paul, MN | Phone (507) 459-4465