Net negative wind pressure on MWFRS sloped roof? 1

[reverbz]

Hey Guys,

When following chapter 28 for MWFRS I'm noticing I get net negative wind pressure on at least some sloped roofs (meaning more wind opposite direction than towards the building). Does that seem correct? Or is there something I'm not looking at correctly? As it is I'd only consider the walls.

The windward zone on the roof is giving me -.69 pressure coefficient and the leeward zone is giving me a -0.48 pressure coefficient meaning the wind would be pulling back towards the windward side?

 

[DaveAtkins]

Yes, that can happen with certain slopes. That is why the Code requires a minimum wind load on the projected area of the building.

 

[lexpatrie]

Read the footnotes in the Tables.

 

[TheDW]

I prefer chapter 27 where they have the specific alt load case with the smaller positive pressure on the windward side