Safeway Fire

[wit-nit]

Originally Posted by Ponderosa

Not too many commercial properties with pitched roofs out there. The driving factor is HVAC and other equipment needed for a large building. They are not really flat. Usually problems arise when the drains plug. This is a great time though to warn everyone - NEVER buy a house with a flat roof. They all leak sooner rather than later.

Our 40 year old house has never had a roof leak. Our previous 23 year old flat roof house never had a leak either. We've had several neighbors with pitched roofs that did leak at one time or another.

[slowesthand]

clean up on aisle 5....

[KO Stradivarius]

I found this story on AZFamily.com today, I think it explains it well. There are some pictures in the story:

Engineer: Flat roofs need TLC during monsoon season - Arizona's Family

A flat roof is not problematic in general -- remember, just about any store or industrial building has one.

But if not maintained, a flat roof could literally buckle beneath the weight of stormwater.

Arizona's Family showed you live images of portions of the Safeway at 35th and Northern avenues collapsing in, and now firefighters think the monsoon storm may have been to blame. There was a downpour of rain, a collapsed roof which likely broke a gas line and destroyed an electric box.The roof itself is something that needs attention in monsoon season. Rain can quickly become the enemy to flat roofs – or nearly flat roofs. Even some homes in the Valley have flat roofs. Structural engineer Hadi Islam says they are designed to balance the natural, gravitational sag of the material with the added weight of pooling water when it rains.

"For some reason, if it is the storm or something like the leaves or some debris is gonna clog, then it’s going to pond more and more. And that is not designed for that," Islam said.

And that’s the key. If scuppers – the drains that direct water back to the ground – aren’t maintained, the roof is going to end up dealing with way more water than it should. So anyone with a flat roof should head up there from time to time, especially when you know a storm is coming.

"Check all the drains are clean before it comes occasionally – I would say periodically – that all the drains are clean," Islam said.

And it’s not just overhanging trees that drop leaves into the drains. Even garbage on the ground can get swept up by the wind and eventually clog a drain on the roof.

[Jnvlv247]

Given the area, it could have been a meth lab gone wrong