Code Reference
StructuralNDS 2018

Section 12.3.1/Dowel-Type Fastener Design

NDS 2018 Chapter 12 covers design of dowel-type fasteners (nails, screws, bolts, lag screws) using yield limit equations.

What this section requires

The design value for a single dowel-type fastener is determined by the yield limit equations, which consider the bearing strength of the wood members, the bending yield strength of the fastener, and the geometry of the connection. The controlling yield mode (I through IV) depends on relative member thicknesses and dowel bearing strengths. Design values are adjusted for load duration (CD), wet service (CM), temperature (Ct), group action (Cg), geometry (C-delta), end grain (Ceg), diaphragm (Cdi), and toe-nail (Ctn) as applicable.

Why this section exists

Wood connections are typically the weakest link in a wood structure. The yield limit model predicts how a fastener and the surrounding wood interact under load. Different failure modes (wood crushing, fastener bending, or a combination) produce different connection capacities. The yield limit equations identify the controlling mode and ensure the connection is designed for the weakest mechanism.

What plan reviewers look for

Plan reviewers check wood connection details for fastener type, size, quantity, spacing, and edge/end distances. They verify that the connection capacity is documented (either by calculation or by referencing NDS Table values). For proprietary connectors (Simpson, USP), they check that the connector model is specified and the installation conditions match the manufacturer's listing.

Common violations

Fastener spacing and edge distance not shown
The connection detail shows the number of bolts or screws but does not dimension the spacing between fasteners or the edge and end distances. Minimum spacing requirements prevent wood splitting and are critical for full-strength connections.
Group action factor omitted
A bolted connection with multiple fasteners in a row does not include the group action factor (Cg), which reduces the per-fastener capacity when many fasteners share the load. This is significant for connections with 4 or more bolts in a row.
Proprietary connector not specified
A connection relies on a proprietary metal connector (joist hanger, hold-down, hurricane tie) but the specific product model is not identified on the drawings. The reviewer cannot verify capacity without the manufacturer and model number.
Compliance tip
Dimension fastener spacing, edge distance, and end distance on every wood connection detail. For bolted connections with multiple fasteners, include the group action factor. For proprietary connectors, specify the manufacturer and model number and reference the evaluation report (ESR or ICC-ES).

Related NDS requirements

Section 3.3.3 covers bending design values for the wood members.Section 3.4.3 covers compression design values. NDS Table 12.3.3 provides minimum fastener spacing requirements. Chapter 12 covers specific requirements for bolted connections.

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Related sections

J3.1Bolted ConnectionsAISC 360-223.3.3Bending Design Value AdjustmentNDS 20183.4.3Compression Design Value AdjustmentNDS 2018