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SDPWS Shear Walls: Engineers Must Check the 0.92 Footnote

October 16, 2026
SDPWS Shear Walls: Engineers Must Check the 0.92 Footnote

SDPWS 2021 tabulates single nominal unit shear capacities, so apply the standard's ASD or LRFD factors to those values, then check Ga for deflection and the 0.92 multiplier in Table 4.3A footnote 10. Pick your wall method early (full-height segments, FTAO or perforated). Distribute story shear by stiffness compatibility or the full-height exception.

TL;DR:

  • SDPWS 2021 LRFD seismic strengths fell about 11% from 2015; update legacy values, and apply the matching ASD or LRFD factor to nominal table capacities.
  • Use full height segments for narrow, regular piers, FTAO for large openings requiring force transfer detailing, and perforated walls when the geometry meets their limits.
  • Include Ga only for shear deformation; total wall deflection also includes bending, anchor or tension elongation, and shrinkage, so compare the value with drift limits.
  • Apply the 0.92 multiplier to OSB or plywood with 10d common nails when the hold down is mounted on the inside face; mark the face on plans.
  • Use stiffness compatibility to equalize deflections; all full height lines may instead distribute by length, applying 2b/h when h/b exceeds 2 and documenting the exception.
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Table of Contents

What changed in SDPWS 2021 and why it matters for your checks

ANSI/AWC SDPWS 2021 replaced separate wind and seismic tabulations with single nominal unit shear capacities for diaphragms and shear walls, and revised the ASD and LRFD factors you apply to those nominal values. For your workflow, that means one table lookup, then a conversion that depends on the load type and design method.

  • Nominal first: read the tabulated value as nominal, never as an allowable value.
  • Convert deliberately: apply the ASD reduction or the LRFD resistance factor that matches the load combination you are checking.
  • Watch the footnotes: AWC's codes and standards summary notes that footnote 10 was added to Table 4.3A, along with other table and equation edits.
  • Read the errata: the 2021 SDPWS errata record clarifications on Ga application, moisture-content adjustments, footnote wording and uplift resistance factors.

LRFD seismic design strengths dropped by about 11% from the 2015 edition after calibration to cyclic testing. If you carry over old LRFD seismic capacities from past projects, update them.

Which shear wall design method fits your wall line?

SDPWS gives you three methods, and SEAU's summary of SDPWS 2021 practice covers each one's aspect-ratio rules and distribution requirements. Choose before you start sizing hold-downs, because the method drives the load path.

  • Individual full-height segments: each pier resists shear on its own. Check the aspect ratio of every segment.
  • FTAO (force transfer around openings): openings are included in the analysis. Straps and blocking carry force around them. Aspect ratio limits apply, and the framer needs clear strap and blocking callouts.
  • Perforated walls: openings are included without FTAO straps. Check the applicable design limits and capacity provisions for the method.

A quick decision rule: if the architect can hold openings to narrow, regular piers, use full-height segments. If large openings must stay in the wall line, use FTAO. If openings are modest and the geometry fits the perforated limits, perforated walls save strap detailing. For the blocked versus unblocked question that follows, see our post on blocked vs unblocked shear walls.

How do vn, Ga and the deflection check fit together?

The shear check takes one of two equivalent forms: V/b < vn, or V < vn × b. Here V is the design shear on the wall line or segment, b is the segment length, and vn is the adjusted unit shear capacity from the SDPWS table, after the ASD or LRFD conversion.

Ga is the apparent shear stiffness. AWC's FAQ on Ga explains that the tabulated values were developed to support seismic story drift and apply to the shear deformation component of total deflection. Total deflection also includes bending, anchor or tension elongation, and shrinkage effects, so Ga alone never gives you the full number.

Ga covers only the shear deformation term, so add the other components before comparing to a drift limit.

A working procedure:

  1. Set the unit shear demand from the story shear and wall length.
  2. Select the sheathing and nailing, read nominal vn, and apply the factor for your method.
  3. Confirm V/b < vn, adjusting for any footnote multipliers.
  4. Compute deflection with the bending, shear (Ga), and anchor elongation terms.
  5. Iterate the nailing or wall length until strength and drift both pass.

Our code-first deflection example walks through the formula with numbers.

What should your drawings say about nails, hold-downs and openings?

Write the full prescribed nail dimensions on the drawings. Design Example 1 commentary notes that SDPWS 2021 prescribes explicit nail dimensions, such as 10d common and 8d common, and removed an implied reduction for short nail lengths. A note reading "use required nails" no longer protects the tabulated capacity.

  • Nail callouts: state type, diameter and length, for example 10d common, not "10d."
  • Footnote 10 factor: Table 4.3A footnote 10 applies a 0.92 multiplier for OSB or plywood with 10d common nails when the hold-down sits on the inside face of the wall. Apply it in the capacity, and show the hold-down face on the plan.
  • Openings: per WoodWorks guidance, openings that materially affect shear-panel strength must be detailed with reinforced edges to transfer shear stresses. Specify sheathing nailing around openings, or include those areas in the opening area per SDPWS Section 4.3.2.3(9).
  • Straps: dimension strap extents around openings so the framer can install them as designed.

Pro Tip: Put the hold-down mounting face and nail schedule in the shear wall schedule itself, not only in a general note. Our nailing schedule guide and permit-ready schedule checklist show layouts reviewers accept.

How do you distribute story shear across a line of walls?

SDPWS accepts two approaches. Stiffness compatibility distributes shear so that all walls in the line deflect equally. Because wall stiffness depends on the shear each wall carries, you usually need iteration.

The exception applies to lines composed only of full-height segments. There you may distribute shear in proportion to length, with the 2b/h adjustment for segments where h/b exceeds 2. Document your use of the exception in the calculations.

A compact procedure:

  1. Make an initial distribution, proportional to wall length.
  2. Compute each wall's vn check and its deflection.
  3. If deflections differ, redistribute shear toward the stiffer walls and recompute.
  4. Stop when deflections match, or, for an all full-height line, record that you used the exception and why it applies.

Where do you find worked examples and calculation resources?

Start with primary documents, then use tools to speed repetitive work.

  • SDPWS and errata: the AWC SDPWS page and the errata linked above are the authority for table values and footnote wording.
  • Code adoption: IBC 2021 Section 2306.3 states that wood-frame shear walls shall be designed consistent with SDPWS.
  • APA material: APA's shear walls and diaphragms page points to SDPWS Tables 4.2B and 4.3A and summarizes common sheathing and fastening assemblies.
  • Design examples: the ICC design example above steps through a full check.
  • Calculators: use them for speed, repeatable results and permit-ready reports, and hand-check critical walls.

What pitfalls show up most in practice?

Read the footnotes and the latest errata before you finalize any shear wall. Most capacity mistakes I see trace to a skipped footnote, not a wrong equation. Write exact fastener dimensions and the hold-down mounting face on the drawings, since the field builds what the sheet shows. Then split your review: run the calculator or spreadsheet for speed, and hand-check the walls that govern the building. A fast tool finds problems early. A hand check is what you can defend to a plan reviewer.

— Evalin

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FAQ

What is the main change to SDPWS shear wall tables in 2021?

SDPWS 2021 moved to single nominal unit shear capacities instead of separate wind and seismic tabulations. You then apply the revised ASD or LRFD factors to the nominal value. See the AWC SDPWS 2021 page for the standard itself.

Can I use Ga for wind deflection calculations?

Ga values were tabulated to support seismic story drift and apply to the shear deformation component of total deflection. AWC's FAQ on Ga explains when applying them to wind deflections is appropriate. Check that guidance before relying on Ga alone.

When does the 0.92 factor in Table 4.3A apply?

Footnote 10 applies the 0.92 multiplier for OSB or plywood with 10d common nails when the hold-down is mounted on the inside face of the wall. Show the hold-down face and nail type on the drawings so the factor matches what gets built.

Do openings in shear walls need reinforcement?

Openings that materially affect shear-panel strength must be detailed and have their edges reinforced to transfer shear stresses, per WoodWorks guidance. Small openings may go unreinforced only if they do not materially affect strength.

Where do I check for SDPWS corrections?

Consult the current AWC errata before finalizing designs. The 2021 SDPWS errata records clarifications on Ga application, moisture-content adjustments, footnote wording and uplift resistance factors.

Sources