Code Value For Cut Nails? 1

[UTvoler]

I have a situation where a wood framed structure (2x6 studs at 16" o-c, 2x6 top/bottom plates) was built with interior load bearing walls that were fastened to slab with masonry cut nails about 32" o-c. The inspector has asked for verification that no other fastening (i.e., bolts) are required. In looking into this, I find no indication in the IBC or NDS that cut nails exist (as far as Code as concerned).

Does anyone have any experience with this? Are cut nails a valid way to fasten a wall bottom plate to a concrete slab per any code, and is there any code values? From a design standpoint there would be a nominal 5 psf lateral load, so not much capacity required to resist lateral forces at the base of the wall.

 

[WARose]

I've always taken it as: NDS covers this by what it refers to as "spike" nails. The NDS yield limit equations (and withdraw) are both still applicable.

The hard part (for me) has always been: what "D" to use in the equations/tables? Since most cut/spike nails I have used previously have had a constant thickness on one side....(and that has typically been thinner than any dimension in the other direction).....I've just used that gauge in calculations.

 

[UTvoler]

Thanks WARose, I don't know how I didn't connect "cut nail" with "spike". Thanks very much for the reply!

 

[Ron]

Assuming your project is in Virginia, the Virginia Residential Code requires either anchor bolts with plate washers or approved tension straps embedded in the concrete. Cut nails are not approved.

Keep in mind that cut nails are trapezoidal shaped. In shear, they typically have good capacity; however, in tension pull-out they will tend to have a non-ductile failure mode and when they start to pull out, they will fail quickly.

You have an uplift and overturning anchorage requirement....not just a shear requirement.

The Wood Handbook, prepared by the Forest Products Laboratory of the US Forest Service, does not recognize cut nails as one of its characteristic nail types/shapes for fastenings (see Chapter 8).

Tremont Nail Company makes a variety of cut nails, but they provide no engineering information.

 

[msquared48]

In years past, contractors used to attach 16 d nails to the sill plates and wet set the plate. Not the best, but provide some shear. Some reversed the heads for better withdrawal. However, I would never rely on nails for any uplift force. No exceptions. Western Woods Use Book has similar information.

Mike McCann, PE, SE (WA, HI)