Unusual Construction In Seattle – CSES Engineering


10 foot cantilever over the driveway

Because the Seattle DPD is committed to increasing housing density, and making our neighborhoods more workable, there are lots of ‘skinny homes’ going up in Seattle neighborhoods, especially Wallingford and Ballard. These are sort of a compromise between a single family residence and an apartment, trying to preserve the best of both. They are usually tightly packed, and to help provide off-street parking, sometimes unusual construction is used.

Have a look at the end of this 10 foot cantilever over the driveway, to allow a car to enter the garage while providing greater living space above. A potential buyer was concerned about some slight downward deflection of the cantilevered portion. The asked me to provide an assessment. I did not find any problems, and the deflection was due to slight warping of the supporting wood beams under load. No problem.

In my own design, I try to avoid that, since it’s a bit unsightly. The way to minimize it is by oversizing the cantilevered beams by 10 to 20 percent.


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