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"Standard of Practice" for wood-frame earthquake retrofit tie-downs

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This is a question for SF  Bay Area engineers who do residential or light commercial earthquake retrofits for wood-framed buildings.
 
For cripple walls that are not very tall (say 18 inches or less), tie-down installation becomes a problem.  Most engineers will have some degree of confidence that the self-weight of the building will resist overturning up to a certain level, without doing extensive calculations to determine tributary loads.
 
What calculated "raw" uplift (overturning moment/shear wall length, ignoring self-weight) do you categorically ignore?   500 pounds?   750 pounds?  1000 pounds?   Or do you consider each case individually, and use your experience and judgment to decide whether you need a tie-down to resist 751 pounds?
 
Feel free to e-mail me off-list.   If I get enough off-list responses to average, I will post the result with any highlights.  I'm counting on you, Ralph....   ;-)
 
Thanks,
 
Thor Matteson