Nails and Horizontal Shear 1

[EIT2]

In the APA Table for Recommended Shear for Horizontal APA Panel Diaphragms ..., we are only allowed to specify 10d nails at adjoining panels if the framing is 3" nominal.

Does anybody use 3" nominal framing?

Are there alternatives?

Are there more current APA table?

Is there revised information on fasteners such as those with a ringed shank that may have greater pull-out values?

Any increase factors for fasteners applied with air guns?

Thank you!

 

[rlflower]

3" nominal width in framing is common.

Correct me if I am wrong, but I do believe it is correct to interpet this requirement as 3" nominal in width, or 2 1/2". If you use a 2 x 4 flatwise, that gives you a 3 1/2" wide nailing surface. Similarly, I-joist products typically provide a nailing surface that is at least 2 1/2" wide.

Try contacting Trus Joist MacMillian.

No, APA does not currently provide an alternative to this requirement. Yes, using a different type of fastener would have some effect upon the panel's performance; however, remember that these tabulated values are based upon lab test results. Any variance from the parameters of these lab tests with the intent to obtain better design values could only be accepted if proven by another lab test. So, yes, go ahead and use wood screws, etc., but you cannot convince any plan checker that screws provide a better value than what's shown in the table for nails. (any way you look at it, you're "screwed" -- just kidding!)

Be careful in specifing the use of air guns for nail placement. Be sure that the air pressure in the gun is restricted such that the result is no more than if you used a conventional hand-held hammer. We do not want to allow the nail head to penetrate the top ply of the plywood any more than would occur with a hand-hammer.

Another thought: look into the actual size of the "10d nail" used in the nail gun -- it likely is not the same as the conventional 10d nail. However, it is often considered an acceptable substitute.

Enough said?

-Richard L. Flower, P. E.

 

[ERV]

The proper nail is a 10D short (2 1/4&quot, the framing members must be a nominal 3" width (2 1/2" dressed). 3" members are only required if the nailing schedule is 3" o.c. or closer with 10D nails. 8D nails are allowed for 3" nailing into 2X. When the need arises for blocked diaphragms with 2", 2 1/2" or 3" o.c. nailing w/ 10D nails I usually specify 4x members, this is pretty common for flexible diaphragms (such as concrete shear walls and wood roof diaphragm. NOTE: 2x4's flat are not allowed.
In the case of trusses with 2X cords it is permissable to double up the cords, however, the nailing for the scab must be checked.
You may use 10D nails if the spacing is 4" o.c. ore further.
For more information on this see UBC97 Table 23-II-H page 2-287

 

[EIT2]

ERV,

How do you know the "proper nail is a 10D short (2 1/4&quot"?
Where is this stated?

Thank you!

 

[ERV]

EIT2,

Experience. A 10D common nail is 3" long and as such tends to split lumber regardless of 3X members. The code (IBC or UBC) requires 1 5/8" penetration into main members, given 5/8" sheathing a 2 1/4" nail provides the required penetration.

 

[boo1]

my exp is that 3" is not normal framing". Typically 2 by xx is used.

 

[RockEngineer]

Sometimes you will get a really picky plans checker for the local jurisdiction that insists that double 2x is not per code and that single 3" nominal material is required. Since you usually can't buy 3" nominal treated boards for sill plates or for the edge boards on your highly loaded shear planels you end up using 4x for framing materials and sill plates. Often these same picky plans examiners authorize aternate braced wall panel designs issued by their office that use double 2x for the sill plates and panel nail edge boards. They don't have a good explanation as to why that is allowed in their alternate braced wall panel and not in an engineered shear wall. The fun of dealing with government.

 

[ERV]

The problem with using 2X's doubled up is this:

If panels edges occur on a doubled up member, and 10D nailing is specified, lets say @ 3" o.c., then the doubled up member would probably have to be nailed to each other somewhere close to the same schedule in order to keep them from pulling apart. This will most likely detroy the integrity of the two members. This amount of nailing is certainly not allowed by NSD.

3X members are specified to eleviate splitting of the member thereby keeping the integrity of the member.