This is an EPDM (rubber) roof; it was installed over an existing built up (tar and gravel) roof; due to a number of factors it consistently held about 4″ of water on its surface. Although the name can be deceiving, a flat roof needs slope; not a lot, just enough to encourage the water to drain off to a gutter or roof drain within 24-36 hours after a rain. This house used to hold about 2″ of water all year round; if the owner wanted to he could have started a brine shrimp farm. [Read more…]