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RE: Standard of Care: Investigation of Existing Building Structure for Alteration or Addition

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This is a very broad question, could you give us a few more specifics?
Several people have already given answer to the general question.  The best
answer I can give you is "Are you comfortable with the new/existing
situation?"  Whenever possible I base my assumptions on existing
documentation.  When that is not available, you are left with conservative
assumptions, experience with construction from that era, and/or testing.
Our office has been using a liberal interpretation of the beginning of that
chapter.  If the new situation increases the stress less than 5% of what is
already there, we consider it okay unless there is some obvious reason to do
otherwise.

As for era of construction, I have worked on buildings back into the 1910
era.  No existing documentation, we did a field survey for general material
condition and placement (wall type, joist spacing / spans, etc) .  The
proposed new loading was less than the original design loads and we saw no
conditions that warranted concern.  The goal was not to provide the same
level of safety as for new construction, but to ensure that the framing
would not fall on anyone's head under normal use.  Unfortunately, this is
full of "engineering judgment", and is not based on any strict code
interpretation.  It basically says, "Its been there for 90 years with no
damage, who am I to judge something that is proven to work?"  Unless we are
directed to do more, we generally base our assessments on "no visible signs
of distress."  Talk to your owner and find out what kind of service they are
looking for.

Off on another note, this building had 4 foot thick stacked sandstone walls.
Was formerly a two story school-house that was to be converted into a bed
and breakfast.  Developer ran out of money and didn't finish the job.

Best of luck,

Jake Watson, P.E.
Salt Lake City, UT

-----Original Message-----
From: Bill Polhemus [mailto:bill(--nospam--at)polhemus.cc]
Sent: Monday, October 07, 2002 7:04 PM
To: seaint(--nospam--at)seaint.org
Subject: Standard of Care: Investigation of Existing Building Structure
for Alteration or Addition


IBC Section 3409.4 states "The owner shall have a structural analysis of the
existing building made to determine adequacy of structural systems for the
proposed alteration, addition or change of occupancy. The existing building
shall be capable of supporting the minimum load requirements of Chapter 16."

The Code goes on to state that a report detailing the results is to be
submitted to the Building Official, who will then "determine whether the
existing building" including the alteration or addition, is in compliance.

The questions I have in this regard are as follows:

1. What is the minimum standard of care that should be observed in gathering
the data used to perform the afforementioned structural analysis? Put
another way, what level of data gathering should be performed? Destructive
investigation where necessary, including core testing of concrete or coupon
testing of steel, among other things?

Or is it sufficient to make certain reasonable, perhaps conservative,
assumptions?

2. How should this data be gathered? Has anyone performed this kind of thing
on a low-rise commercial building of venerable age--say fifty years or more?
How did you do it? Did you employ, say, a surveyor? Or a material test
company?

Does anyone have any suggestions as to who I might contact to gather this
level of data?

Thanks in advance for your input.


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