box gutters

waterproofing decks

Flat metal roof with 20 year warranty

“Twenty-year material warranties are customary for metal roofing systems, which is considerably longer than the standard protection for built-up and single-ply systems. Long-term warranties are sometimes offered for weathertightness on metal roofs, including those with a 1/4:12 slope.”

http://en.wikipedia.org/wiki/Roof

“Metal standing seam roofs are becoming increasingly common on low sloped roof assemblies.

Residential roof designs in mild climates or where there is little precipitation tend to exhibit lower pitched roofs and drainage at the exterior wall; an example of residential flat roof is that of the adobe construction in the American Southwest.