Return to index: [Subject] [Thread] [Date] [Author]

Re: nailing zones in plywood diaphragms

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Roger Turk wrote:

>I'm afraid that you misunderstood what I wrote.  The transition is made 
>beyond where the nailing with the **lower** capacity is adequate.
I think we are saying the same thing a transition is made and the higher 
capacity nailing overlaps the lower shear zone.  I took the original question 
as asking specifically where the nailing changes from one spacing to another. 
 Sooner or later you have to change the spacing. My point is this should 
occur at a panel joint, purlin or joist, and if this is the case you will 
have different nail spacing on one side of the panel joint than the other.  

If the transition splits a panel you would have a different spacing from one 
side of the panel from the other. 

>Since the nailing with the larger nail spacing (lower capacity) is already 
>more than adequate (if it isn't, it *should* be) for the shear force at the 
>transition location, why have two different nail spacings on each side of a 
>plywood joint?  As for your question, "If not there, then where?", what is 
>wrong with having the transition location between 
>joists/purlins/girders/plywood joints?  In fact, with staggered end joints, 
>you will not have adjacent panels ending at the same location anyway. 
Except at every other panel. As I stated in my previous post, and above.  
Case2 the nail spacing from one side of the panel to the other changes.

In Case 4 where the load is parallel to the purlins, if you make the 
transition between purlins, you will have different nail spacing from one end 
of the panel to the other and the nail spacing along the other edges will 
transition somewhere along the side edge of the panel.  

IMO, in the field it's easier for the nailing to change over a framing member 
from a standpoint of giving everyone involved a reference line to work from.  

J. Thomas Jakaby, SE
Jakaby Engineering
San Jose, CA