Reply #8: Speaking as an architect...

[never cry wolf]

Who specializes in industrial buildings, no roof is flat. They all pitch some. Yes, it is more economical but it is also more practical. If you had a building with a 300' depth just how would you propose to build a sloped roof. Wood is out in a building that size due to building codes, prefab steel trusses are too large to transport and field fabricating a steel truss would be very labor intensive and costly.

In addition, sloped roofs have their own variety of problems. For a standard industrial building or strip mall the gutters would have to be HUGE, like 24" wide and 24" deep. What do you do with that water? Spill it onto grade, in many municipaitites that is illegal, not to mention that you would create an ice rink at each downspout in the winter. Sliding snow also plays havoc with gutters, and anything that happens to be underneath it. Leaves, birds nests, etc. also make a gutter system a pain in the ass to maintain, plus they freeze.

With a nominal flat roof system, the roof pitches to roof drains spaced every so often. These run into internal downspouts which never freeze and are piped directly into the storm water management system underground, again, no freezing, no maintenance.

I am not familiar with the building failure you mention above, but the building codes are quite strict as to what a roof load needs to be engineered for. Add to this about 3 layers of safety factors build into all structural design and if engineered and constructed properly there would be no collapses, even under more that design loads. A building that fails generally has human error as the cause. If designed properly, a "flat" roof is a much more efficient receptor for rain and snow than a sloped roof.