Nail Withdrawal Design Value (NDS 12.2.3)
The design number behind the framer's 'nails don't hold in withdrawal' instinct, which fastener-pullout only tabulates: NDS W = 1,380 G^(5/2) D lb/in, times the penetration. A 16d common nail (D 0.162) in DF-L (G 0.50) gives 39.5 lb/in, so a 1.5 in bite holds 59 lb; toenailed at wind duration the 0.67 Ctn nearly cancels the 1.6 CD bump - the reason toenailed uplift is weak and framing hardware replaces it. Side grain only (no end-grain withdrawal). A design aid, not the engineer of record's stamped design.
Formula and source
W = 1,380 G^(5/2) D (lb/in); Ctn = toenailed ? 0.67 : 1.0; Z_w = W x p x CD x Ctn.
The NDS 2018 12.2.3 reference nail/spike withdrawal design value and the toenail factor, by name; the 1,380 empirical constant is named.
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