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Re: Common versus Box Nails

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Re: Your Tue, 15 Jun 1999 16:55:39 EDT posting

Ray, Three points:

It looks like you are dealing with an existing home built under the 1985 UBC
and which now is the subject either of alterations or more likely, of
litigation. 

The answer I would testify to in expert opinion is that AT THAT TIME,
architects, plans drafters, contractors, framers, building inspectors, and
MOST engineers would regard box nails as essentially interchangeable with
common nails for purposes of UBC shear nailing schedules. That longstanding
UBC table accepted on its face two nail types of dramatically different wire
diameters, and it is hard to imagine that any difference made by galvanizing
--and there are thin, smooth galvanizing coatings as well as rough hot-dip
coatings-- would amount to much, and the need for rust-resistance is
ordinarily negligible in covered sheathing. Thus the code's authority
coupled with a common-sense interpretation of galvanizing's value for box
nails leaves a logical impression to a reasonable mind that nail diameter
really wasn't significant.
________________

Since the 1991 NDS it is clear that nail wire diameter is the key strength
characteristic after all. If you are designing an alteration or addition,
you might revalue the shear nailing according to the actual nail wire gage
in place.  

On nail names, it is a "common" mistake to suppose that all nails not
"common" are by default "box" nails, especially for 8-penny size, where
available wire gages include .131, .120, .113, and .099 of an inch, with
common and box at the extremes of that range. 

I find 8d/.113 nails favored by framers, and I design accordingly, using UBC
table values for 6d/.113 common nails.

Central Section of SEAOC had a presentation on this subject a week ago, by
Chuck Shubnell, general manager of Golden State Nail Co. in SoCal, phone
909-899-5000, and we learned that exact nail head style isn't significant
among the range of non-finishing/casing nail types. Chuck had a major role
in their product line's testing for ICBO ER-2843 now in effect.       
___________

I sure wish we would go easy on use of the term "standard of care". This is
a legal "term of art" that has definitions in officially approved jury
instructions, in published, precedent-setting appellate court decisions, and
in legal encyclopedias like Cal Jur 3d. Whether a person has fulfilled a
standard of care is determined by judge (or jury, when used) based on law
and upon expert testimony as to certain factors. "How things ought to be" is
a Rush Limbaugh book title, not a basis for declaring standard of care
retroactively. 

As for framers exercising a "standard of care", this is a misapplication of
a term used to describe discretionary acts by professionals, not by framers
following a design professional's spec. Where framers ARE acting at their
own discretion, as for most features of most residential jobs, their
obligation under their own Contractors License Law is to follow "accepted
trade standards for good and workmanlike construction." [Cal B&P Code sec
7109(b)]

Legal work is in a world of words, not mental intentions. (Remember what
turned on the definitions of "is" and of "sex") It is very important to mind
the quality of our words, to get what we want in engineering and not cause
unwanted calamity to ourselves.

Charles O. Greenlaw  SE   Sacramento CA