Notched and tapered member ends

The end of a simple-span sawn lumber or glulam bending member, by NDS 2024 3.2.3, 3.4.3, 3.4.4, 4.4.3 and 5.4.5. The end is either notched or taper cut over its bearing, or hung on a connection. An interior notch can be added. The shear at the notch, the bearing, the bending at the reduced section and the code's notch limits are checked under the member's own reactions. LRFD or ASD.

Inputs of the notched end #

• Member: sawn lumber (species, grade, nominal size from the Supplement Table 4A, 4B and 4D values) or glulam (stress class, width and depth; Supplement Table 5A values, read 2026-11-12). SCL, I-joists and CLT follow their manufacturers' notch rules and are not offered.
• Span and loads:
  • Span: centre to centre of the bearings, the clear span plus half the bearing at each end (3.2.1).
  • Loads: uniform dead, live, roof live and snow loads in plf, including the member's weight, combined by ASCE 7-22. The reaction at each end is w L / 2.
• Member end:
  • No notch: bearing at the end.
  • Notch on the tension face: the bottom cut over the bearing, so the member bears at dn.
  • Notch on the compression face: the top cut at the end, running e past the inner edge of the support.
  • Taper cut on the compression face: the top cut from the member end down to full depth at e past the support. Its depth is the depth removed at the member end; dn is taken at the inner edge of the support (3.4.3.1(e)).
  • Hung on a connection: bolts, lag screws, split rings or shear plates (3.4.4), with the effective depth de and the distance from the member end. de is the depth less the distance from the unloaded edge to the nearest bolt or lag screw centre, or to the nearest edge of a ring or plate (Figure 3E).
  • A taper cut on the tension face is entered as a tension-face notch, as 3.4.3.1(c) treats it.
• Notch depth (d − dn): your input, set by the support detail (a seat or ledge height, a flush top). Auto-design keeps it.
• Bearing length lb: at the member end, so Cb = 1.0 (3.10.4).
• Interior notch: sawn lumber only.
  • Its face: tension, only for members thinner than 3-1/2 in.; or compression.
  • Its distance from the bearing centre to its near edge, its depth and its length.
• Service conditions: wet service and temperature. The load duration factors and the live-load time effect factor are in the code options.

Auto-design (editor toolbar) varies the sawn size, or the glulam width and depth. Objective: the least wood. The notch depth, its length, the bearing, the connection, the span and the loads stay yours. A member too shallow for the notch fails the code limit, and a deeper one is found.

Checks performed #

The shear is taken at the support and equals the reaction, without the reduction for loads near supports (3.4.3.1 and 3.4.2.2 apply that reduction only to members without notches). The drawings are:

• the end elevation (the notch or taper, the bearing block, or the connection);
• the interior notch, when there is one;
• the member section.

Limitations #

• The member away from its ends: flexure with CL, unnotched shear and deflection are the member's own calculation (wood beam, glulam beam).
• Simple span only: uniform loads by type; no point loads.
• Bending at the notch: taken with CL = 1.0. The member's lateral stability is checked in its own calculation.
• Measurements:
  • The middle-third limit and the glulam 3 dn and 3d lengths are measured from the member end (lb + e), as Figure 5F draws them. This is on the safe side of the middle-third rule.
  • The sawn taper limit (d/4) is checked on the depth removed at the member end. This is also on the safe side: Figure 4B shows dn at the bearing.
• Not offered: circular members (Eq. 3.4-4), notches in SCL, I-joists and CLT, notches on both faces at one section (prohibited for glulam by 5.4.5.3).
• Glulam values: the Table 5A values (Fvx, Fc⊥x, Fbx) were read against the Supplement on 2026-11-12 (p. 80).
• Equation numbers: the NDS 2024 scan numbers two equations 3.4-6 (in 3.4.3.1(f) and in 3.4.4.1(a)). The steps name both the equation and its clause.

Verification examples #

Verification status: 15 values compared in 8 examples (0 published, 8 hand calculations from the cited equations): 15 within tolerance, 0 recorded deviations. No published example: every value is a hand calculation. That checks the program against this reading of the code, not the reading itself. Code basis: not yet recorded for this module.

Neither the NDS 2024 nor its Commentary works a notched member example, and AWC's Structural Wood Design Examples are listed as needed. Every value is a hand calculation of the code's equations with the Supplement values (Douglas Fir-Larch No. 2) and, for glulam, Table 5A 24F-1.8E (to be confirmed against the code text). They cover:

• a tension-face notch in LRFD and ASD;
• the bearing;
• a compression-face notch with e ≤ dn and with e > dn, and its net section;
• a glulam tension-face notch with Cvr;
• a connection near and far from the end;
• interior notches on both faces.