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Re: Wood: Conventional Framing opinions needed from other states

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FLew98 wrote:

> ...
> Now lets apply this example to seismic/structural design of houses.  I assert
> that the avoided costs of conservative seismic design for houses can offset
> many times over the costs of  "Y2K-level" expenditures for repairs after a
> damaging event.  I'll use round numbers to make the math easy, but the
> magnitudes should be valid.  Assume that, due to engineering fees and extra
> labor and materials above and beyond what contractors would do under
> prescriptive requirements, engineered houses cost an average of $1,000 more
> than non-engineered ones.  Some 1.2 million new housing units are built
> annually in this country.  Assume that half of them are engineered because
> they are apartments, custom homes or mobile homes.  That leaves 600K units
> that will incur the added costs if Dennis would have his way - $600 million
> *annually*, or about $13 billion in the interval between the San Fernando and
> Northridge events.  And that's not including ROI results.  Yet, the vast
> majority of the 13 million non-engineered housing units built during that
> interval won't experience strong ground shaking during their service life..
> To impose a 100% solution on a 5% problem is a questionable use of society's
> resources, and questionable public policy.   And it may not even be 5% - it's
> unlikely that all the damaging earthquakes in the U.S. in this century,
> collectively, damaged as much as 5% of the country's housing stock (or even
> California's).
> ...

A few comments on your analysis.

Since your $13 billion is to cover the nation as a whole, you should not limit
your damage mitigation side of the equation to earthquake, but you show also
include snow, wind, and a few other miscellaneous items like , vertical load
failures, foundation failures, garage headers that sag (causing loss of value),
leaks contributed to by large deflections, sleep lost due to creaky walls, excess
heating and cooling costs if windows or door seals unseat, et cetera (perhaps even
including some construction phase collapses).

While engineering may mitigate some or most of these costs, it will not mitigate
all.

The cost of damage in not only the repair or replacement cost, but also the value
associated with the disruption to the lives of the occupants (and maybe a few
medical bills and legal bills which can mount very quickly).

The interval between San Fernando and NorthRidge events is, IMHO, shorter than the
service life of most homes.

$1000 per unit sounds low to me, you get very little engineering or structural
observation out of $1000.

The 1906 earthquake (and fires) wiped out a large section of San Francisco.  At
that time wouldn't this have represented a large percentage of total housing in
the state?

If we engineer zones 3 and 4, or just zone 4, the ratios could change a great deal
from what they look like if we engineer all zones.

Stan Johnson, PE, (how about damage from really loud rap music from cars driving
by at 1 am?  I mean, we are talking West Coast.  ;^)