Sources & references
Every external reference our calculators rely on, listed by calculator — plus an honest note about what is an assumption rather than a citation.
Our sourcing philosophy is deliberately narrow: a few high-quality, stable references — safety agencies, code organizations, and trade associations — cited only where a claim actually rests on them. Quantities that reflect common industry practice rather than a published standard (typical bag yields, screw counts, coverage rates) are labeled as assumptions on each calculator page instead of being given decorative citations. How assumptions and sources fit together is explained on the methodology page.
Deck Material Calculator
- 811 Before You Dig — Common Ground Alliance (accessed 2026-07-25). Free national utility-locating service. Referenced for all digging safety guidance.
- Prescriptive Residential Wood Deck Construction Guide (DCA 6) — American Wood Council (accessed 2026-07-25). Referenced for the reminder that joist spans, beam spans, and footing sizes must be verified against prescriptive tables or local code — not for any quantity used by this calculator.
Fence Material Calculator
- 811 Before You Dig — Common Ground Alliance (accessed 2026-07-25). Free national utility-locating service. Referenced for all digging safety guidance.
Paver Patio Calculator
- 811 Before You Dig — Common Ground Alliance (accessed 2026-07-25). Free national utility-locating service. Referenced for all digging safety guidance.
- Interlocking Concrete Pavement Institute technical resources — Concrete Masonry & Hardscapes Association (CMHA) (accessed 2026-07-25). Referenced for general segmental-pavement practice (compacted aggregate base, ~1 in bedding sand). Base depths on the page are labeled as assumptions to adjust for local conditions.
Gravel Driveway Calculator
- 811 Before You Dig — Common Ground Alliance (accessed 2026-07-25). Free national utility-locating service. Referenced for all digging safety guidance.
Concrete Slab Calculator
- 811 Before You Dig — Common Ground Alliance (accessed 2026-07-25). Free national utility-locating service. Referenced for all digging safety guidance.
- Ready Mixed Concrete Resources — National Ready Mixed Concrete Association (accessed 2026-07-25). Referenced for general ready-mix ordering practices (never round an order down).
Mulch Calculator
- Mulching Landscape Trees — Penn State Extension (accessed 2026-07-25). Referenced for the guidance to keep mulch off trunks/stems (no 'volcano mulching') and that over-deep mulch harms roots. The calculator's default depth stays a user input.
Flooring Calculator
- Protect Your Family from Sources of Lead — U.S. Environmental Protection Agency (accessed 2026-07-25). Referenced for pre-1978 renovation safety warnings.
- Lead Renovation, Repair and Painting Program — U.S. Environmental Protection Agency (accessed 2026-07-25). Referenced for the pre-1978 warnings that work disturbing painted surfaces should follow RRP lead-safe practices or use an RRP-certified firm.
Tile Calculator
- Tile installation standards overview — Tile Council of North America (accessed 2026-07-25). Referenced for the guidance that coverage of setting materials varies by trowel, tile size, and substrate. Coverage numbers in the calculator are labeled assumptions based on typical manufacturer bag specs.
- Protect Your Family from Sources of Lead — U.S. Environmental Protection Agency (accessed 2026-07-25). Referenced for pre-1978 renovation safety warnings.
- Lead Renovation, Repair and Painting Program — U.S. Environmental Protection Agency (accessed 2026-07-25). Referenced for the pre-1978 warnings that work disturbing painted surfaces should follow RRP lead-safe practices or use an RRP-certified firm.
Paint Calculator
- Protect Your Family from Sources of Lead — U.S. Environmental Protection Agency (accessed 2026-07-25). Referenced for pre-1978 renovation safety warnings.
- Lead Renovation, Repair and Painting Program — U.S. Environmental Protection Agency (accessed 2026-07-25). Referenced for the pre-1978 warnings that work disturbing painted surfaces should follow RRP lead-safe practices or use an RRP-certified firm.
Drywall Calculator
- Protect Your Family from Sources of Lead — U.S. Environmental Protection Agency (accessed 2026-07-25). Referenced for pre-1978 renovation safety warnings.
- Learn About Asbestos — U.S. Environmental Protection Agency (accessed 2026-07-25). Referenced for demolition and disposal safety warnings in older homes.
- Lead Renovation, Repair and Painting Program — U.S. Environmental Protection Agency (accessed 2026-07-25). Referenced for the pre-1978 warnings that work disturbing painted surfaces should follow RRP lead-safe practices or use an RRP-certified firm.
Dumpster Size Calculator
- Learn About Asbestos — U.S. Environmental Protection Agency (accessed 2026-07-25). Referenced for demolition and disposal safety warnings in older homes.
Generator Size Calculator
- Carbon Monoxide Information Center — U.S. Consumer Product Safety Commission (accessed 2026-07-25). Referenced for carbon-monoxide safety warnings: never run a portable generator indoors or in a garage, keep it at least 20 feet from the house with exhaust facing away, and use battery-backed CO alarms.
- Carbon Monoxide Hazards at Work — National Institute for Occupational Safety and Health (CDC) (accessed 2026-07-25). Referenced for the warning that CO from portable generators and other gasoline engines can accumulate to fatal concentrations within minutes, even in areas that appear ventilated.
- Portable Generator Safety — Electrical Safety Foundation International (accessed 2026-07-25). Referenced for the backfeed warning: never connect a generator to household wiring without a transfer switch — backfeeding can electrocute utility workers.