Roof Top Privacy Fence Wind Loads

[XR250]

Got a client who wants a ballasted privacy fence around their patio on top of their 5th story condo. Should I treat this as a parapet or a sign or something else for wind loads?

 

[KootK]

Parapet sounds good to me. Especially if there's no significant avenue for wind to flow beneath the screen. Substantial loads, I'm sure.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[XR250]

Thanks KootK. I imagine the amount of ballast I am going to need will be overload the floor system. Say I only have 2' of solid screen above a 3' open guardrail, would you still call that a parapet?

 

[KootK]

In that case, I'd lean towards treating it as a sign. Keep in mind, however, that I'm almost a decade removed from US practice. In the Canadian wind load provisions, the important difference between sign treatment and parapet treatment seems to be the ability for the backed up air to escape beneath the air blocking surface as well as over top of it. At least that's my interpretation. You know how it is with wind. You get to chose among several simplified options, none of which completely fit your situation. If I were back in WI around the time of Y2K, this probably would have been 30 psf and done

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[XR250]

Yea, I was thinking about using 25 psf and calling it a day. It still won't likely work due to the limited floor capacity. I hate when the scope creeps on these jobs. If they had told me up-front that they wanted to do this I would have let them hire someone smarter (or dumber) than me.

Thanks for the advice.

 

[SAIL3]

physically it resmbles a sign but in air flow conditions that a parapet typically sees...so pick your poison...from a quick look at ASCE 7-10, looks like the drag coeff could be a min of 2.5