How the checks, counts and numbers on this site are made
Every tool page says the canvas “checks” some things and tells you to measure others yourself. This page lists exactly what is checked, where each rule comes from, how the calculators count, and how the pages are written. Nothing on the site is an AI guess: the editor is a rules engine with the numbers below, and the calculators are the arithmetic they describe.
01
The 15 rules the editor checks
Each rule is a distance measured on the drawing between an item and the nearest wall, fixture or door swing. “Code” rules are taken from the 2021 International Residential Code (IRC) as published; “guide” rules are industry recommendations that most designers follow but no inspector enforces. Your jurisdiction may amend the code figures; the editor does not know where you live.
| Rule | Required | Kind | Source |
|---|---|---|---|
| 15 in from the toilet centreline to a wall or fixture on each side | 15 in / 381 mm | Code | IRC 2021 R307.1, Figure R307.1 |
| 21 in clear in front of the toilet | 21 in / 533 mm | Code | IRC 2021 R307.1 |
| 21 in clear in front of a sink | 21 in / 533 mm | Code | IRC 2021 R307.1 |
| 21 in clear in front of a tub | 21 in / 533 mm | Code | IRC 2021 R307.1 |
| 24 in clear in front of the shower opening | 24 in / 610 mm | Code | IRC 2021 R307.1 |
| shower compartment at least 30 × 30 in inside | 30 in / 762 mm | Code | IRC 2021 P2708.1 |
| 42 in work aisle between a counter and the island or opposite run | 42 in / 1067 mm | Guide | NKBA Kitchen Planning Guidelines |
| 36 in in front of a washer or dryer | 36 in / 914 mm | Guide | NKBA / appliance makers’ installation guides |
| 24 in walkway at the foot of a bed | 24 in / 610 mm | Guide | planning practice (not code) |
| 24 in on at least one side of a bed | 24 in / 610 mm | Guide | planning practice (not code) |
| nothing standing inside a door’s swing arc | — | Guide | planning practice (not code) |
| 60 in from every rail of a pool table for a 57 in cue | 60 in / 1524 mm | Guide | Billiard Congress of America room-size guidance |
| 30 in clear in front of a furnace or water heater | 30 in / 762 mm | Code | IRC 2021 M1305.1 |
| 36 in deep, 30 in wide working space in front of an electrical panel | 36 in / 914 mm | Code | NEC 110.26 (IRC E3405) |
| 7 ft ceiling in habitable rooms, 6 ft 8 in in bathrooms and laundry | 84 in / 2134 mm | Code | IRC 2021 R305.1 |
Not checked, so measure it yourself: egress window size and sill height, stair rise and run, handrails, smoke alarms, structural spans and headers, plumbing vents, electrical outlet spacing, energy code, accessibility beyond the fixture clearances above, and anything in a commercial code (IBC, NFPA 101, local health code).
02
How the calculators count
- Studs: wall length ÷ spacing, rounded down, plus one; four more per door or window (two king, two jack or cripple), two per corner or intersection; 10 percent waste. Three plates per wall.
- Drywall: wall area = perimeter × height minus 3 × 6 ft 8 in per door and 3 × 5 ft per window; ceiling area optional; sheets rounded up with 10 percent waste; one bucket of compound per 450 sq ft, 250 ft of tape and 250 screws per roll and pound. The same formula runs the materials list on the canvas.
- Area and volume: square feet × depth in feet ÷ 27 for cubic yards; tons by typical delivered density (gravel 1.4, crushed stone 1.5, sand 1.35, topsoil 1.2, mulch 0.5 tons per cubic yard). Compaction allowances are stated on the page, never hidden in the number.
- Decks, fences, pavers, office space: each page prints its own formula and assumptions next to the result, and the worked examples in the text were produced by the same code, so they can be reproduced by typing the same inputs.
03
How the pages are written
- Every dimension or requirement quoted in the text has a source in that page’s Sources list: the code section, the industry guideline or the manufacturer document it came from.
- The fixed room layouts were drawn in this editor and pass its own checks (closed rooms, no overlapping furniture, doors that can open, the clearances above) before they are published.
- Each page shows its publication and last-change dates, taken from the content’s revision history, not set by hand.
- Pages state plainly what the tool cannot do: no photos, no 3D model, no AI-generated plans, no stamped drawings. The 3D render button is the one place an image model is used: it paints a picture over the plan you drew (FLUX.1 Kontext on fal), is labelled as an AI image wherever it appears, and is never used to check or measure anything. If a page oversells, that is a bug.
04
Corrections
If a number on any page is wrong, out of date, or does not match its cited source, tell us at aitaylorfan@gmail.com. Corrections are made on the page and move its “updated” date.