Architectural Flashing Supply
Start a Quote
ASCE 7 wind load fundamentals · Lesson 3 of 4

ASCE 7 wind load fundamentals: methods and worked application

A worked example from a trade seminar: velocity pressure, four roof zones, the zone width, conversion to allowable stress, a trap in the source, the square law, and a comparison that depends on the safety-factor convention.

You will be able to: Build a zone pressure by hand from written-down inputs, convert between strength level and allowable stress, compare it with a published rating, and document every assumption.

12 min · 11 slides · 10 questions

All lessons in this module
Slide 1 of 11

The method as a form

Wind pressure work starts with a form, not a calculator. Before any arithmetic, write down the wind speed V and where it came from, the risk category, exposure, mean roof height, Kzt, Ke, enclosure class and the ASCE 7 edition.

Write the level, strength or ASD, beside every pressure.

Sources

Glossary

Effective wind area
The area over which a wind pressure on a component is averaged. Small areas, like edge metal, get larger coefficients; the edge-metal examples here use 10 sq ft.
Zone width a
The width of the roof perimeter and corner zones in ASCE 7-16: the smaller of 0.4 times height and 0.1 times the least width, not less than 0.04 times the least width or 3 ft, as presented in the SPRI deck.
Strength level
A pressure from ASCE 7-16 wind speeds without the 0.6 allowable-stress factor. Allowable-stress pressures are the strength-level value times 0.6.
Engineer of record
The licensed engineer responsible for a project's design. This person chooses the wind inputs and the safety-factor convention; a worked example or screening never replaces that decision.