Wind Loads...Bldg with Parapet Wall 1

[ToadJones]

What is considered the ridge height and eave height on a building with a parapet wall?
I have a building with a monoslope roof. Parapet is 5ft on the low side and 3 ft on the high side.
The actual frame has a low eave height of 52ft and max height on the high side of the monoslope of 55ft.

ASCE 7-05

What is the ridge and eave height considered to be?

 

[ron9876]

Parapet doesn't matter for the building. Depends on the roof slope. The average eave height if slope is greater than 7 degrees and the eave height if less than 7 degrees. ASCE7 doesn't say but I would use the higher eave height. I am assuming MWFRS.

 

[ToadJones]

thanks ron...makes sense

 

[TXStructural]

For wind on the roof, use the top of parapet to determine the roof height, since the wind which matters is the wind that reaches the roof, over the top of the parapet. And you are probably being too precise if the difference between 50-somthing and 50-something-else feet high is complicating computation of the wind pressures. The difference should be trivial.

After all, even for the latest revision, we are talking about an estimated projection of winds over the next 50 years, rounded to the nearest convenient 5 or 10 mph increment, based on fewer than 500 weather stations nationwide, some of which had as little as 5 years of historical wind records. And we almost all get the same non-hurricane wind speed.

 

[Ron]

Parapets are rarely more than a few feet high. The tables are not that precise, so use the parapet height. Fairly often the high side of the monoslope coincides closely to the top of the parapet. Agree with TX