Wood stud wall
Bearing studs at a spacing under axial load and out-of-plane wind, to NDS 2024 3.6 to 3.10 and 15.4 with ASCE 7-22 combinations, in ASD or LRFD. One stud is designed for its tributary width (the stud spacing); the studs are pinned at the plates.
Inputs of the stud wall #
- Studs: species, grade and size (2x4 to 4x8 dimension lumber), plies per stud, spacing, height and the repetitive member factor Cr (three or more studs at 24 in or less with sheathing, NDS 4.3.9).
- Bracing: Ke (1.0 for studs pinned at the plates), the weak-axis bracing (sheathing fastened to the studs, blocking at a spacing, or none) and whether both stud edges are braced for bending (sheathing or finish on both faces, CL = 1.0). These are your judgment; the usual values are prefilled.
- Loads: axial loads per foot of wall per load type with an eccentricity (its moment adds to the wind moment), and the wind pressure W on the wall (the ASCE 7-22 components and cladding pressure, strength level, acting in both directions).
- Plates: the species and grade of the plate under the stud and whether Cb applies (the stud bears at least 3 in from the plate end).
- Wind deflection: the wind load factor (IBC Table 1604.3 note f permits 0.42 of the components and cladding load) and the limit height / n (360 plaster or stucco, 240 other brittle finishes, 120 flexible finishes).
Auto-design (editor toolbar) varies the stud size, plies and spacing (12, 16, 19.2, 24 in.); grade when unlocked. Objectives: least wood per foot of wall; lowest cost index. Kept unless you select them: grade. Every other input is kept; see Auto-design.
Checks performed #
| Check | Basis |
|---|---|
| Slenderness | le/d ≤ 50 about both axes (3.7.1.4) |
| Stud compression | fc ≤ Fc' = Fc* CP, CP of the governing axis (3.7.1) |
| Combined bending and compression | Eq. 3.9-3 under each combination with wind, with its CD or λ; Eq. 15.4-1 when the axial load is eccentric; Fb' with Cr and CL |
| Shear from wind | fv = 3V/(2A) ≤ Fv' |
| Bearing on the plate | fc⊥ = P/(b d) ≤ Fc⊥' of the plate with Cb (3.10.2, 3.10.4) |
| Wind deflection | 5wℓ⁴/(384 E' I) with the reduced wind load, against height / n |
Drawings #
The drawing sheet (Drawing sheet / DXF buttons, and the report appendix) shows a representative length of wall: studs (and plies) at the designed spacing, the plate the studs bear on, the stud height, blocking rows when the weak axis is braced by blocking, and the wall loads by type along the top; and the stud section. Wall length, openings, headers, sheathing, the number of top plates and anchorage are not part of the calculation and are not drawn; the wind pressure and the bracing basis are in the sheet notes.
Limitations #
- Openings, headers, jack and king studs, the sheathing and its fastening, and the in-plane shear of the wall are not covered (see the shear wall module for in-plane design).
- Checked against the NDS 2024 text (steps cite section and page): Tables 2.3.2, 2.3.3, 2.3.5, 2.3.6, 4.3.1, 4.3.8, N3; 3.3.3 (CL, RB ≤ 50, now checked when the compression edges are not braced), 3.7.1, 3.9.2, 3.10.2, 3.10.4, 4.3.9 (Cr) and 15.4 (Eq. 15.4-1 with Eq. 15.4-2). Corrected: the plate bearing Fc⊥' takes no λ in LRFD (Table 4.3.1).
- Reference values and the Table 4A / 4B size factors stay marked [verify]: the NDS 2024 Supplement is not on disk (
research/DOCUMENTS_NEEDED.md). Stud grade wider than 6 in and Southern Pine grades other than No. 2 are reported as not feasible.
Verification examples #
NDS 2024 has no worked stud wall example. The module is verified against Aghayere & Vigil, Structural Wood Design 2nd ed., Example 5.9 (published values as tabulated in the free calcs.com validation page; its ASCE 7-16 snow load is entered as S / 0.7 and its plate bearing without Cb, as in the example) and hand calculations in closed form of the NDS 2024 equations (backend/tests/test_verify_stud_wall.py):
| Example | What it checks | Published / hand value | ILX Calcs |
|---|---|---|---|
| AV-5.9 | 2x6 DF-L No. 2 at 24 in, 10 ft, per stud D 1440 + L 640 + S 1440 lb, W 25 psf | P = 3000 lb, CP = 0.492, Fc' = 840 psi, utilization 43.3 %, plate Fc⊥' = 625 psi, Fb' = 2153 psi; under D + 0.75(L + S + 0.6W): CP = 0.377, Fc' = 896 psi, Eq. 3.9-3 = 0.49 | 3000, 0.4915, 839.3, 43.3 %, 625, 2152.8; 0.376, 893.7, 0.491 |
| HAND-1 | 2x6 DF-L Stud at 16 in, 10 ft, D 300 + L 400 plf, W 25 psf | Fc' = 597.6 psi (D + L), Eq. 3.9-3 = 0.330 (D + 0.6W, ASD), 0.433 (1.2D + 1.0W + L, LRFD), plate Fc⊥' = 781 psi, Δ = 0.108 in | same |