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Excavation Sloping/Benching Setback Calculator

Calculate the minimum horizontal setback for a sloped excavation wall, using OSHA's maximum allowable slope ratios by soil type.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-26 · v1.0.0

Market
Imperial · sales tax

Minimum required horizontal setback

9.84 ft

Check your inputs

Soil classification (Type A/B/C) MUST be determined by a competent person using OSHA 29 CFR 1926 Subpart P Appendix A's field tests (not assumed) — misclassifying soil is a common cause of excavation collapse. This simple-slope method is only valid for excavations 20 ft (6 m) or less in depth; deeper excavations, benched configurations, or soil with seeping water require the full Subpart P tables or a registered professional engineer's design. Type A soil has a further exception (1/2:1 for short-term cuts ≤12 ft) not implemented here — use the more conservative 3/4:1 ratio shown unless your competent person confirms the exception applies.

Slope ratio used (horizontal:vertical)
1 :1

Official municipal inspection prerequisites — United States

Checked against ICC / ACI requirements for the currently selected market. Switching market re-runs these checks.

  • COMPLIANT — Simple slope method valid only to 20 ft (6 m) depth; deeper cuts need an engineered design.

    Depth 3.0 m is within the 20 ft (6 m) simple-slope range, provided a competent person has classified the soil.

    29 CFR 1926 Subpart P, Appendix B · 29 CFR 1926 Subpart P App. B

These checks cover only the specific thresholds listed above. They are not a complete code review: fire separation, egress, structural capacity and accessibility provisions are outside their scope, and only the handful of local amendments offered in the selector are modelled — your municipality may have others. Final approval rests with your local building authority.

For the dimensions entered, expect a minimum required horizontal setback of 3. Moderate confidence — sound arithmetic, but allow for the variation any real site introduces. Set for United States against IRC 2024. The market selector changes both the units and the code cited.

Estimated cost — your price

This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • Per OSHA 29 CFR 1926 Subpart P, Appendix B (verified against the regulatory text), for excavations 20 feet or less in depth using a simple slope configuration, the maximum allowable slope ratios (horizontal:vertical) are: Type A soil 3/4:1 (0.75), Type B soil 1:1 (1.0), Type C soil 1 1/2:1 (1.5). Type A soil has a further exception allowing 1/2:1 for short-term excavations of 12 feet or less, not implemented in this simplified tool. Required horizontal setback = Excavation Depth × Slope Ratio.

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Frequently asked questions

What are OSHA's maximum allowable slope ratios by soil type?
Per OSHA 29 CFR 1926 Subpart P, Appendix B, for excavations 20 feet or less in depth using a simple slope configuration: Type A soil 3/4:1 (0.75), Type B soil 1:1 (1.0), and Type C soil 1 1/2:1 (1.5), expressed as horizontal:vertical.
Who decides the soil classification (Type A, B, or C)?
Soil classification MUST be determined by a competent person using the field tests specified in OSHA 29 CFR 1926 Subpart P, Appendix A — it must never be assumed, since misclassifying soil is a common cause of excavation collapse.
Does this method apply to any excavation depth?
No — this simple-slope method is only valid for excavations 20 ft (6 m) or less in depth. Deeper excavations, benched configurations, or soil with seeping water require the full Subpart P tables or a registered professional engineer's design. Type A soil also has a further exception (1/2:1 for short-term cuts ≤12 ft) that is not implemented in this simplified tool.