I can give you a litle history. "Prairie school" architect John van Bergen designed many homes with "ponded roofs" the idea was that evaporating water would somehow cool the structure.

He was a draftsman for Frank Lloyd Wright and Walter Burley Griffin. I think he was doing ponded roofs in the 1930's

Go to the website :   http://www.rebuilding.com/johnvanbergen/title.html   to see his designs and some drawings.

architect Barton Myers’s Toro Canyon house has pond roofs.  great house triple glass garage doors to creat indoor outdoor space. might be worth checking with them.

Previously Miguel Diego wrote:

I am in the final planing stage for a new house that will have a roof pond to cover approximately 700 sqf of the roof. Any advise on waterproofing materials, pond roof design considerations, etc would be much appreciated.