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Re: Plywood over light gage shear wall

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Tom-

I was  just going by the footnote in the report........I didn't even look at the photos since I figured scaling them would be pretty rough.

But looking at the photos I'd have to agree with you....no way those "bugle" heads are anywhere near 13/32, your estimate of 1/4 to 5/16 is way better than the report text of 13/32.

I was actually getting confused between the bugle heads (used for sheathing) & the washer heads (used for frame assembly) which have a pretty goog head on them.

I think the "newer" Ply-Tek's (?) with the reaming wings are a much better screw but I don't know if they're in the code & whether or not they're used in the field.  

As I remember, when we sheathed the test panels, we had trouble with screws lifting the sheathing off the framing when the threads engaged in the plywood.....plus we had trouble with overdrives because the heads wouldn't stop the screw & the some of the drivers we used tended to "coast".  We got the process bugs worked out after the first few panels.

Next time I'm in the vicinity of the lab, I'll checkout the screws.....I'm sure the box of screws we used is still in the "research fastener" cabinet.


btw I don't think you're splitting hairs    I think it's important to know what we really used in those test samples.


Now my question is......where did that 13/32 number in the footnote come from?   Maybe a mistake?  s/b 11/32?


cheers
Bob

On 5/23/07, Tom Skaggs <tom.skaggs(--nospam--at)apawood.org> wrote:

Check out Figure 2.6, the head diameter looks smaller than 13/32 to me…  I got the same "scaling" using the better photo of between ¼" and 5/16"…  But, perhaps I'm splitting hairs…

 

Tom

 

From: Robert Kazanjy [mailto:rkazanjy(--nospam--at)gmail.com]
Sent: Wednesday, May 23, 2007 11:52


To: seaint(--nospam--at)seaint.org
Subject: Re: Plywood over light gage shear wall

 

Tom-

Oops!  Did we neglect to give dimensions of those screws?  

I sure hope they're on the CD somewhere

cheers
Bob

PS  found this link

http://www.icbolabc.org/graphics/pdf/cola-rpt.pdf

I assume this is some sort of subset or super set of the CoLA data

head dia given in footnote on page 3-8  13/32    .406  (min)

On 5/23/07, Tom Skaggs <tom.skaggs(--nospam--at)apawood.org> wrote:

According to COLA Report, screws were "No. 8 x 1" Quadrex tapping (bugle head) screws).  ICBO ES-5202 covered the screws at the time.  I did not see dimensions in the report, but there is a photo (black and white) that shows a screw next to a tape measure.  Head diameter appears to be between ¼ - 5/16", but this is a rough estimate based on a distorted black and white photo printed from a laser printer…

 

Tom

 

-----------------------------------------------------------------------
Thomas D. Skaggs, Ph.D., P.E.
Manager, Product Evaluation

Technical Services Division
APA - The Engineered Wood Association
7011 S. 19th Street
Tacoma, WA 98466
ph: 253/565-6600
fx: 253/620-7235
-----------------------------------------------------------------------

 

 

 

From: Robert Kazanjy [mailto:rkazanjy(--nospam--at)gmail.com ]
Sent: Wednesday, May 23, 2007 11:19
To: seaint(--nospam--at)seaint.org
Subject: Re: Plywood over light gage shear wall

 

Jim-

That's a pretty small head diameter for a self driller / tapper for use in plywood

A number of years ago we did plywood shear wall (CoLA Shear Test Program) over steel studs & I recall that the screw heads were more like 3/8" or even larger.  

I don't have the data readily available due to a crash   .........  archived  somewhere

Maybe the specs have been changed but it seems to me that a bigger head (3/8 or 7/16) would be better than .292" .  A head dia of .292 seems  pretty skimpy.

The screws were #8's or 10's


cheers
 Bob

On 5/22/07, Jim Bessley <jbessley(--nospam--at)gmail.com > wrote:

I am trying to design a shearwall using the 2003 IBC for plywood sheathing over light gage metal studs.  the code says that the screws should be self drilling and tapping screws with a .292" head diameter.  I can't find the screw size that correlates to this head diameter.  Can anybody out there help me.

thanks,
Jim Bessley