Disclaimer

Every calculator page ends with the same planning disclaimer. Span and footing pages repeat it above the tool. Stair, railing, and deck pages also show the code-edition note beside the checks.

Results are estimates for planning purposes only and are not a structural design. Building codes vary by location; always confirm with your local building department. For structural elements (spans, beams, footings), consult a licensed engineer or contractor.

Code checks reference the 2021 International Residential Code (section numbers for the 2024 edition shown in parentheses). States and cities adopt different editions and often amend them, so limits in your area may differ.

Deck stair checks follow the American Wood Council's DCA 6 prescriptive guide, which is based on the 2015 IRC; your inspector may apply a different standard.

Based on the IRC model code. Your local jurisdiction may adopt a different edition or amendments — confirm with your building department.