A client I had helped complete a two-story addition and kitchen remodel a few years ago recently contacted me about building a deck and pergola. He sent some rough outdoor-living concepts to me, which I drew in SketchUp. After a few go-arounds, he settled on a design he liked.

The client found and purchased the new pergola system online. The manufacturer was Steel Shade Pergolas located in Tulsa, Okla., a fair distance from sunny Southern California. After the usual delays at the building department, the owner obtained a building permit, which is when I got a look at the pergola manufacturer’s plans. The first thing that struck me was the size of the footings: 4 feet square by 2 feet deep. Also, I noticed that the pergola was powder-coated steel—with the largest steel member weighing in at roughly 275 pounds.

I contacted the manufacturer to find out why the footings needed to be so large. Though heavy to install, the finish pergola didn’t weigh all that much. I was told that because the company sells pergolas nationwide, it has a universal structural design primarily focused on wind loads. Per the manufacturer’s data, these pergolas can withstand a substantial wind load of 110 mph in an Exposure B urban-suburban setting. Where this house was located, in the center of Los Angeles, it would likely not experience wind speeds that great; though in nearby Malibu, the Santa Ana winds can reach 70 mph or higher (in December 2011, the Santa Anas were clocked at a continuous 97 mph with gusts up to 167 mph in Malibu).

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