ASCE 7 Wind Enclosure - Definition of Openings

[JAE]

I did some searches here but didn't find a direct thread that asks this question:

When using ASCE 7 in non-hurricane debris regions (i.e. 90 mph - or the new 115 mph zones) what is the practical definition of an opening?

The ASCE 7 doesn't do very well in defining what an "opening" is.
The commentary suggests "operable windows, doors, louvers, etc."

But why would a door be an opening? Most doors are mostly closed, especially during high wind events.
You could argue that the door might get busted open by the wind but wouldn't that be even MORE applicable to non-operable windows, which apparently aren't considered as an opening.

I can see gaps around doors also - but the area of the gaps is very small and wouldn't much affect the enclosure calculations provided.

Any thoughts on this?

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[Ron]

JAE....one of the most confusing issues in the code!!

An opening was previously defined as any appurture of 4sf or larger or any accumulation of 4sf of opening...as an example, a large hangar door with a rubber gasket could exceed the 4sf criteria when the gasket deflects under wind load. Another implication when you are doing the calcs for deciding partially enclosed for wind borne debris is that an opening counts only if it receives positive pressure, presuming that negative pressures would receive no debris.

 

[msquared48]

JAE:

The code assumes people, like Ernest, are forgetful, leaving doors and windows open. It also assumes worst case scenarios are the default condition. Also could pertain to skylights that can opened.

Mike McCann, PE, SE (WA)

 

[charliealphabravo]

In a Florida jurisdiction where I did a lot of work the CBO required windows (4sf) to be considered openings unless they were rated impact resistant. I think we had to consider wind rated doors as openings as well.

 

[DaveAtkins]

Over the years, I have noticed pre-engineered metal building designers assume windows and doors (even large overhead doors) are NOT openings. So, this is the assumption I usually make.

But I do agree this is not the worst case scenario.

Maybe the assumption is if a 90 mph (115 mph) wind storm is predicted, the building owner will "batten down the hatches."

DaveAtkins