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Shear Walls and 3x Framing (UBC) STAGGERING

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I have The "Diaphragms and Shear Walls Design/Construction Guide"  2001 APA
(APAL350G.PDF). Page 32 shows that the staggering of nails is to be in both
directions, parallel and perpendicular to the stud. I took Mr. Utzman's
graphics and corrected it. The above reference is the only reference I have
ever found that clarifies the problem. What would we do with out APA?

Here is what page 32 shows...

       o            o          o          o
o            o         o            o
_____________________________
       o            o         o            o
 o            o         o            o


I got the first conclusion from purely the code, by observing how the terms
"stagger" and "offset" are used and related them to a possible directional
relation with the stud. I also applied the engineer's comment that it is
"impossible to staggered".  That is true if staggering at joining edges
means to have four rows of nailing and a 2x is allowed. The table 23-II-I-,
note 4 states  "Plywood joint...nailing shall be staggered in all cases"
That, as a separate sentence, might be interpreted to include a "case" of
shear less than 350 lb/ft, where a 2x is allowed. If that is used, then
staggering is impossible if meaning "four rows of nailing".

I recommend designing with the APA guide, but question condemning some
varying staggerings. When should nailing be pulled and renailed? When is a
stud over nailed and needs replacing?

David Merrick, SE


From: chuckuc 
Subject: Re: Shear Walls and 3x Framing (UBC)

David-

Hmm--where did you get that idea that staggered nails are in a single
line? "Offset" panels are arranged so as to keep splitting loads from
highly loaded edges from falling on the same stud (requiring a panel
displacement of 16"). Staggering nailing is intended to avoid stud
splitting (ideally .5" to avoid same grain splitting problems).

Like this:

       o            o          o
o            o         o            o
_____________________________
o            o         o            o
       o         o            o



Not  like this
o         o          o        o            o
_______________________________
    o          o          o            o


I finally added a little detail on my drawings to clarify.

Chuck Utzman,P.E.


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