Replies

1. 
   Guest_ | Jun 14, 2000 10:09pm | #1

   *
   I don't know the answer but manufacturers have to have the info so you can call them. The Structural Tables Library, University of British Columbia has lots of info on nailing regimes; etc.

   I sunk 2400 deck screws a few weeks ago and only two bent; none broke. I reused the bent screws and they were fine; no twisting off heads or broken shanks. I will be replacing nails with flooring and decking screws in almost every application more and more from now on.

1. 
   Guest_ | Jun 14, 2000 11:16pm | #2

   *Someone correct me here...I have always been of the understanding that the shear value relates to the product you are installing..( OSB, Ply, whatever ) not the actuall fastener??

1. 
   Guest_ | Jun 15, 2000 02:50am | #3

   *While I would assume that someone has the shear value of a bare nail, if you are interested in the shear value when the nail is used in construction, you probably need to consider the material and the tension that the nail creates between the materials being fastened. I don't recall ever running into values for nails per se, but somewhere that I can't find, I should have some nailing schedules for different materials - particularly the nailing schedules for plywood used as shear walls for seismic retrofits. I vaguely remember in a class many years ago studying shear values for rivets and bolts used in structures, and the value was partly depended upon the friction created between the two materials being joined which depended upon the contact area created between the two surfaces by the fastener tension (or something like that...) Of course, this all could have just been a dream during one of the times I nodded off in that class...Anyway, about the only example I could find of a nailing schedule on the Internet is:http://www.mcvicker.com/resguide/page014.htmActually, as I think about it, I can't remember many nails failing by being sheared off (the head maybe) - usually they either pull through the wood, or the lateral forces cause the hole in the wood to be enlarged and the nail bends and pulls out. If you can't find shear figures for nails, since most common nails are simply short snips of mild steel wire with a point and a head pounded on, perhaps you could get a rough idea by looking at an engineering handbook and getting the shear figures for the appropriate diameter steel wire. If I remember correctly, in the late 1980's, drywall screws were not allowed in constructing shear walls for seismic retrofit in the S.F. Bay Area, but this might have only been regarding drywall screws and not the more maleable deck screws. Does anyone know the general code requirements on allowing screws in seismic shear walls?

2. 
   kevin_yrene | Jun 15, 2000 06:35am | #4

   *
   Bill, I dont know the exact shear value numbers, but I think a good place to start would be a nail and screw wholesaler/contractor supplier. I do know that a 16D sinker has a shear value of 150# and a 3" zinc coated screw shears at approximately 800#. Hope that helps a little.

3. 
   Guest_ | Jun 15, 2000 12:49pm | #5

   *
   Mark and Casey are correct - you need to be concerned about the strength of the wood around the nail, not the nail itself. You can find info about it in NDS-95 (national design specification) but it isn't easy to figure out. The strength of a fastener varies depending on the wood species, grade, the number of pieces the nail passes through, and the direction of the grain. (Wood can handle more pressure parallel to the grain than perpendicular)

   Wood screws aren't generally allowed in structural applications, as there are no real standards for the diameter of them.

   I think Kevin's numbers for 16D nails are a bit high, and the 3" screw is way out there. The 16D is probably only about 100# in SYP, perpendicular to the grain.

1. 
   Guest_ | Jun 15, 2000 09:39pm | #7

   *Just looked in my reference book to see if such an answer exists. No luck. Logic says that the shear value of the fastened material is the deciding factor not the fastener. It also says that the manufacturing method for nails and screws would yield large variations from one lot to another.I suspect that is one of the reasons our nailing schedules are so conservative.If you are designing and building so close to the limits the actual values are important it probably would be best to contact the manufacturer for specific information on the specific lot you are using.

4. 
   William_Hastings | Jun 15, 2000 09:39pm | #6

   *
   Can someone tell me the shear value of a 8d common nail, 10d common nail and where I can reference this info? Also I'd like to know the shear value of #8 and #10 2 1/2 inch long wood to wood screws so I can interchange these fastners when necessary. Thanks Bill