Methodology
Our Standards
All calculators on TradeCalc are built against recognized industry standards and codes. Each calculator cites its source on the page so field workers can verify results. The codes we reference, by trade:
Electrician — NEC 2023
National Electrical Code (NFPA 70). We cite Article 210/215 for branch circuits and feeders. Article 220 covers load calculations. Table 310.16 gives conductor ampacity, and Chapter 9 holds conduit fill tables.
HVAC — ASHRAE & ACCA
ASHRAE 62.1-2022 for acceptable indoor air quality. ASHRAE Fundamentals for load and duct sizing. ACCA Manual J 8th Edition for residential load calculation.
Plumber — UPC & IPC
Uniform Plumbing Code (IAPMO UPC) Chapters 6 (water supply), 7 (sanitary drainage), 11 (storm drainage), 12 (gas piping). International Plumbing Code Tables 604.5, 709.1, 710.1 plus Appendix C/E. ASPE Plumbing Engineering Design Handbook Vol. 2. IAPMO/ASPE Water Demand Calculator (UPC Appendix M, 2021+).
Roofer — IRC & ASCE 7
International Residential Code R802 (roof framing), R905 (roofing), R301 (structural loads), R806 (attic ventilation). ASCE 7-22 Chapters 7 (snow load) and 16 (rain load). IECC Tables C402.1/R402.1 for insulation. SMACNA Architectural Sheet Metal Manual for gutters, downspouts, flashing.
Review Process
Each calculator undergoes a multi-step review before publication: formula verification against source standards, boundary-case testing with known values, cross-referencing with manufacturer data sheets, and usability testing on mobile devices. We maintain a test suite that validates calculation accuracy across all supported calculators.
AI Use
Guides are drafted with AI assistance and reviewed by our editors. While AI helps draft guide content and structure calculations, all formulas are verified against their source standards. AI does not replace professional engineering judgment — it assists in content creation and formula implementation.
Editorial Model
TradeCalc publishes under a brand organizational byline. Guides are drafted with AI assistance and every formula is code-reviewed against the cited building code. We do not claim individual credentialed reviewers — instead, each calculator page lists the specific code sections it references so you can verify results against the primary source. If you spot an error, contact us and we will correct it and cite the fix.
Last updated: July 2026