Test Allowable Area

Single-building allowable-area gut-check — proposed building area and stories versus the IBC Ch. 5 allowable area calculation (tabular base × open-frontage modifier × sprinkler factor) — against IBC text the user supplies.

This command does not carry IBC values. Every limit cited in the output is a verbatim quote from text the user pasted, or text the command fetched from an explicitly-named official URL with the user's authorization.

For a multi-occupancy / mixed-use Ch. 5 audit, use the code-review skill. For a single § interpretation use /explain-code.

Inputs the command needs

1. Occupancy group — IBC Ch. 3: A-1 … S-2. Mixed-occupancy must use IBC §508 (separated / non-separated / accessory) — flag and route.
2. Construction type — IBC Ch. 6: I-A, I-B, II-A, II-B, III-A, III-B, IV-A, IV-B, IV-C, IV-HT, V-A, V-B. Drives base allowable from Table 506.2.
3. Provided values — labeled:
   • Total building area sf (sum of all stories in the area-calculation envelope per §506.1.2)
   • Largest single-story area sf
   • Number of stories above grade plane
   • Building height ft (top of roof per §502)
4. Sprinklered status — non-sprinklered, NFPA 13 (commercial), NFPA 13R (low-rise residential), NFPA 13D (1-and-2-family). Sprinkler factor (Is) applies per §506.3 only with NFPA 13.
5. Open frontage — perimeter ft open to public way / yard ≥ 20 ft, used for If factor per §506.3.2. State the F/P × W measurement.
6. Jurisdiction — base IBC always applies. Stricter overlays:
   • NYC BC (Ch. 5 amendments)
   • California Building Code Part 2
   • DSA (CA K-12)
   • CA HCAI (CA hospitals)
   • OBC 2024 (Toronto Building, different framework)
7. Source for the operative tables / § text — paste / fetch / arch-rag:
   • Paste verbatim IBC Table 506.2 row (occupancy + construction type) and Table 504.3 (stories) and Table 504.4 (height in ft), with citation headers.
   • Paste verbatim §506.3 allowable area formula and §506.3.2 open-frontage definition.
   • Fetch from AHJ amendment page where free.
   • arch-rag if IBC PDF indexed locally.

The command refuses to compute against recalled allowable values.

Workflow

1. Echo parsed inputs: occupancy / construction type / provided area + stories + height / sprinklered / open frontage / jurisdiction.
2. Identify reference area: IBC Ch. 5 — General Building Heights and Areas. Tables 504.3, 504.4, 506.2. Calculation in §506.3. Do not claim specific values from recall.
3. Acquire source text (table rows + formula §).
4. For overlay jurisdictions, require overlay text or stop.
5. Math against verbatim source:
   • Apply the formula Aa = (At + NS × If) × Sa (or per the verbatim source — quote it)
   • Compute If from (F/P − 0.25) × W/30 per §506.3.2.
6. Output table + attribution + caveats.

Output template

# Test Allowable Area — [Occupancy + Construction Type, plain title]

**Occupancy:** [B / R-2 / A-3 / mixed]
**Construction type:** [I-A / II-B / V-B]
**Provided:** [building area X sf / largest story Y sf / Z stories / height H ft]
**Sprinklered:** [NFPA 13 / NFPA 13R / NFPA 13D / non-sprinklered]
**Open frontage:** [F = ... ft, P = ... ft, W = ... ft, F/P = ...]
**Jurisdiction:** [base IBC 2024 / + NYC BC / + CBC / + OBC]

## Reference area
IBC Ch. 5 — General Building Heights and Areas. Tables `504.3` (allowable stories), `504.4` (allowable height in ft), `506.2` (allowable area factor `At`). Formula and frontage in `§506.3`.

## Source text under test
> [Verbatim quote of `Table 506.2` row for the occupancy + construction type.]

(Source: pasted by user / fetched from <URL> on <YYYY-MM-DD>)

> [Verbatim quote of `§506.3` allowable area formula and `§506.3.2` open-frontage definition.]

(Source: pasted by user / fetched from <URL> on <YYYY-MM-DD>)

## Comparison
| Value | Provided | Allowable (per quoted source + math) | Verdict | Margin |
|---|---|---|---|---|
| Allowable stories | ... | "<Table 504.3 row>" | PASS / FAIL / MARGINAL | ... |
| Allowable height (ft) | ... | "<Table 504.4 row>" | ... | ... |
| Allowable area per story | ... | "<§506.3 formula applied to verbatim factors>" | ... | ... |

## Jurisdictional flags
- [If overlay in scope and overlay source provided: include overlay rows.]
- [If overlay in scope but overlay source missing: list the overlay text the user must paste / fetch.]
- [Mixed-occupancy must apply `IBC §508` separated / non-separated / accessory rules — flag and route to `code-review`.]
- [Mezzanine / unlimited-area buildings (`§505`, `§507`) and high-rise (`§403`) trigger separate provisions — flag if applicable.]

## Caveats
- Single-building gut-check; not a stamped Ch. 5 analysis. Mixed-occupancy and special provisions (`§503` general, `§505` mezzanines, `§507` unlimited area, `§403` high-rise) require AOR / Code Consultant scoping.
- Open-frontage measurement is geometry-sensitive. The `F`, `P`, `W` definitions in `§506.3.2` must be applied carefully — many designs miscount frontage along non-qualifying boundaries.
- All limit values come from the source the user pasted or the URL fetched on <date>. The command did not recall any IBC value from training.
- IBC editions and AHJ amendments change. NYC DOB amendments to `Table 506.2` exist for some occupancies.
- Binding interpretation is the AOR's stamped Ch. 5 analysis plus AHJ review.

NA AEC conventions (enforce)

• English only.
• Imperial-first: sf, ft, stories. Metric only if the source uses it (OBC).
• Codes: IBC, NFPA 13 / 13R / 13D, NFPA 101, NYC BC, CBC, OBC, NBC. Reject KBC, KS, EN, BS, JIS, DIN.
• AHJs named: NYC DOB, FDNY, LADBS, DSA, CA HCAI, NYC SCA, Toronto Building, Boston ISD, Chicago DOB. Never the AHJ or the city.
• Floors / stories: Level 3 / L3 / 3rd floor. Never 3F.
• Roles: Architect of Record (AOR), Code Consultant, Fire Protection Engineer, Expediter (NYC). Never Director as a project role.

Constraints

• Never invent allowable area / stories / height values from recall.
• Never paraphrase Table 506.2 / Table 504.3 / Table 504.4 — verbatim only.
• Never claim a specific table number / row from recall.
• For mixed-occupancy, route to code-review — §508 separated / non-separated / accessory rules are out of scope for this command.
• Distinguish NFPA 13 (full sprinkler factor) from 13R / 13D (no Is credit per §506.3).
• Single building, single shot. Multi-building / phased scoping → code-review.
• No docs/ artifact, no Word / PDF, no aec-doc-gen.
• Caveat block always present.
• Fetch only after explicit user authorization.

Anti-patterns (never do)

• Stating allowable values inline ("Type II-B B occupancy = 23,000 sf base") — never. Numbers live only in the quoted source.
• Claiming Table 506.2 row from recall — never.
• Auto-applying Is sprinkler factor without confirming NFPA 13 (vs 13R / 13D).
• Counting frontage along boundaries that don't qualify under §506.3.2 (e.g., neighbor-fence line ≤ 20 ft, internal lot lines).
• Treating mixed-occupancy as single-occupancy.
• Auto-fetching without explicit authorization.
• Hedging — verdicts are PASS / FAIL / MARGINAL.
• Running code-review from inside this command — pointer-only.