From: "Dennis S. Wish" <dennis.wish(--nospam--at)gte.net>
Date: Mon, 22 May 2000 15:44:25 -0700
While I tend to agree wholeheartedly with your comments, I believe that the
non-life-threatening damage caused to residential structures after recent
hurricanes, tornadoes and earthquakes may have been greatly reduced if
conventional framing standards were raised and designers and framers had a
better understanding of Lateral Force Resisting Systems (LFRS).
Historically, NAHB has preferred that engineers NOT be involved in
residential construction. Considering the current code issues, I might agree
with them. However, NAHB, I think, demonstrates that the performance issues
were quality of construction and code enforcement problems rather than code
inadequacy issues. Still, NAHB believes that there should only be a minimum
level of compliance to insure life safety and that this acceptable level of
risk be defined. This essentially negates financial or performance based
concerns. This would also explain why there is no pressing need in the
document to improve conventional construction. The statistics support that
homes constructed by conventional construction provide sufficient protection
against loss of life.
The economic climate in this country has changed significantly since the
early seventies. The financial burden suffered by even moderately damaged
homes can have a dramatic affect upon not only the family in residence, but
upon the community as a whole and further upstream each tax payers burden.
Nothing is more evident of this than the hurricanes, tornadoes and
earthquakes that have occurred in the last twelve years alone.
My point is that there is room for engineers to be involved in the
improvement of conventional (prescriptive) construction standards. Reducing
the cost difference between the minimum engineered home (by code compliance
standards) and current prescriptive methods would reduce the incentive for
builders to make performance choices motivated solely on profit margins.
California home owners learned from developing mitigation methods that if a
homeowner invests $2500.00 to strength cripple walls and anchor plates to
foundations in homes built prior to 1969 and on raised foundations, the
owner could save as much as 10 times this cost (not counting the additional
cost to the insurance industry) to bring a failed home back on to its
foundation and repair consequential damages.
The homes most greatly affected by these codes are owned by those who are
least likely to afford to repair the damage. A survey of homeowners in my
area a few years ago (published in the Desert Sun Newspaper) demonstrated
that the majority of homeowners in an area of greatest risk in the state had
little or no earthquake coverage. The demographics were primarily families
who could not afford the insurance. When homes sit unprepared, the financial
burden is weighted upon the entire community as property values reduce.
None of these points are life-safety issues. This is the problem with the
document - it only attempts to be a "companion" to the code rather than to
suggest replacement or improvement of the code.
I don't think it is time for SEA to step out of residential UNLESS engineers
are able to step into NAHB and raise the minimum level of compliance for
conventional construction. Not only does this include the obvious code
change, but it includes appropriate demonstration of skills by those who are
building conventionally framed homes - from the designer to the framer.
Once this is accomplished, then I would agree with your assessment. The
problem right now is that our Seismology Committee members do not understand
this, are not willing to compromise in spite the lack of evidence that
propels them forward, or they simply do not care about single and two family
homes enough to do something for the millions of people that must live in
NAHB is not ready to run free, but they have taken the Bull by the horns and
have opened a door of opportunity for engineers to become a part of the real
Dennis S. Wish, PE