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RE: UBC: How Do You Interpret 1997 UBC P

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My question wasn't regarding the rationale for live load reduction due to
tributary area-I understand that.

My question was, since several people mentioned LL reduction "by tributary
area" specifically, is there some provision for LL reduction in the code due
to any other reason?

Also, the attorney does seem to sincerely want my professional opinion no
matter what. I should mention that he represents an insurance carrier for
the OWNER. They apparently carry an "excess damages liability" policy that
would pay the cost for the repairs to the parking structure-which are very
real, and very perplexing-OVER AND ABOVE that which the Engineer's E&O would

They are trying to determine whether this was a true "omission" or if the
Engineer's "fault" was in fact minimal. The Engineer appears to be
maintaining that "we designed per the Building Code" (UBC 1994 in this case,
although for some reason the Engineer used 1991 UBC which had been
superceded by the time the drawings went to permitting-a minor point since
it doesn't appear there's enough difference at least in the Live Load
provisions between the two codes to matter. Anyone who begs to differ with
that, please let me know), and thus they are absolved from liability on that

However, it appears from a reading of the Code, that "weasel words" might
carry the day. IMO, there is reason to suggest that "due diligence" was not
pursued in this case. A survey of the literature reveals plenty of reasons
to go with a Live Load in parking structures of this type above the Code
minimum. I say "IMO" because I know how I approach stuff like this: I VERY
CAREFULLY determine if the loads seem acceptable before I proceed, Building
Code minimums notwithstanding. And it was relatively easy with a couple of
days' inquiry (including in this forum, which once again has proved its
value FAR BEYOND any reasonable expectation, thanks to the erudite-as
always-comments received from all of you) to discover there is a rational
basis for going with AT LEAST the 50 psf distributed load with NO reduction
due to tributary area, and with a higher concentrated load as well.

The kicker is the popularity over the past decade of the super-heavy-duty
SUV and similar "pleasure vehicles."

In all honesty I can see it both ways, since the state of our knowledge
about loading for parking structures has only recently caught up with the
reality of the past decade.

At the root of this dispute, the question seems to be "how much 'due
diligence' is actually 'due'?" As someone who detests prescriptive codes,
and who doesn't worry about clients' turning me down (even though I'm just a
humble SOHO) because Fred whom they've used for the past twelve years ALWAYS
gives them a cheaper design than that, it just ain't worth the pain and
agony of just such a dispute as this EOR has been undergoing for the past
four years (that's how long the matter has been in dispute).

Of course, since the owner of this parking structure is a rather prolific
developer of commercial and multi-family residential property, I'm sure they
have in the past represented a lucrative source of work for the EOR, and
based purely on supposition I would guess that one reason they've enjoyed
this long relationship is the owner has come to rely on the EOR's
willingness to skin it close to the bone on his designs.

So the owner has himself to blame in part for this debacle, though I feel
certain that with an attorney on his side to reassure him (and I've read
some of the depositions he's been involved in; he is a REAL jerk), that
thought would NEVER cross his mind.

Business is War.

William L. Polhemus, Jr. P.E.
Polhemus Engineering Company
Katy, TX, USA
Phone (281) 492-2251
FAX (281) 492-8203
email bill(--nospam--at)

-----Original Message-----
From: Roger Turk [mailto:73527.1356(--nospam--at)]
Sent: Wednesday, March 06, 2002 12:18 PM
To: seaint(--nospam--at)
Subject: RE: UBC: How Do You Interpret 1997 UBC P


The live load reduction rationale is based on the assumption that as
tributary area increases, the likelihood of the entire area being loaded the
specified amount diminishes.

* * *

BTW, does the lawyer want you to determine the cause of the problem(s) or is
he/she focusing on the LL reduction.  If the latter, the attorney is looking
for a whore on whose testimony the attorney can base his/her case.

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