| Project | Unit | Limit | Proposed | Parapet | Equipment | Clearance | Method | Effective | Status |
|---|---|---|---|---|---|---|---|---|---|
| Warehouse Bay 3 | m | 12.00 | 11.20 | 0.40 | 0.80 | 0.20 | Highest point | 12.20 | Non-compliant |
| Clinic Annex | m | 18.00 | 16.90 | 0.60 | 0.30 | 0.20 | Top of parapet | 17.50 | Compliant |
| Office Retrofit | ft | 60.00 | 58.00 | 2.00 | 4.00 | 1.00 | Highest point | 63.00 | Non-compliant |
The calculator compares an effective height to a stated height limit. Effective height depends on the measurement method you select.
- Hroof = Proposed height to roof
- Hparapet = Parapet height
- Hequip = Rooftop equipment height
- Hclear = Safety clearance
- Hlimit = Allowed height limit
- Roof height only: Heff = Hroof
- Top of parapet: Heff = Hroof + Hparapet
- Highest point: Heff = max(Hroof + Hparapet, Hroof + Hequip) + Hclear
Compliance rule: Compliant if Heff ≤ Hlimit. Otherwise it is Non-compliant and the exceedance is (Heff − Hlimit).
- Pick the same unit used in your drawings or code letter.
- Enter the official height limit for the site or zone.
- Input the proposed roof height from the chosen grade reference.
- Add parapet, equipment, and a clearance buffer if required.
- Select the measurement method used by the reviewing authority.
- Press Check height to see status and margin.
- Run alternate scenarios and export the session as CSV or PDF.
Permit submittals benefit from consistent height records
Height compliance checks are easier to defend when every scenario uses the same grade reference, method, and units. Keep a short trail: drawing set date, sheet number, and the stated limit from the approval letter. Many teams store at least three scenarios per concept: baseline, conservative, and value-engineered. For multi-phase sites, note the phase, datum, and revision number so later checks reference the same geometry. This keeps coordination meetings focused and reduces rework before submission deadlines.
Grade reference choices can change outcomes
If a review body measures from average grade, the effective height may differ from a finished grade reading on sloped sites. Record which reference was used and avoid mixing references across revisions. Example slope notes help during rechecks when grading plans move by small amounts.
Rooftop elements often decide the controlling point
Parapets and equipment frequently control the maximum. A typical coordination set might include parapets around 0.30–1.20 m and mechanical screens that add 0.60–2.50 m above roof. Use the “Highest point” method when reviewers look at the tallest projection rather than the roof line.
Use margins to manage construction tolerances
A small clearance buffer helps account for as-built tolerances, survey differences, and roof build-up changes. If the tool reports 98–99% of the limit, consider reducing the roof datum or reworking rooftop equipment to regain a practical margin.
Example scenario data for quick checks
Sample: limit 18.00 m, roof 16.90 m, parapet 0.60 m, equipment 0.30 m, clearance 0.20 m. Using “Top of parapet,” effective height becomes 17.50 m and remains compliant with a 0.50 m margin. Using “Highest point,” effective height becomes 17.70 m and remains compliant with a 0.30 m margin.
Tip: Save multiple runs to session history, then export once for internal reviews. Use the percent-of-limit value to prioritize changes and document any approved exceptions.
1) What does “effective height” mean here?
It is the height value compared to the limit, calculated from roof height plus parapet or equipment, and optional clearance, depending on the method you select.
2) Which measurement method should I use?
Use the method required by the approving authority. If unsure, choose “Highest point” to test the strictest common interpretation and reduce approval risk.
3) Why include safety clearance?
Clearance can represent tolerances, roof build-up uncertainty, or a conservative buffer requested by a reviewer. Set it to zero if your review process does not allow buffers.
4) Should parapet and equipment both be added?
Not always. The “Highest point” method uses whichever is taller at the roof: parapet or equipment. “Top of parapet” ignores equipment, and “Roof only” ignores both.
5) What if my limit is in meters but drawings are in feet?
Convert first so inputs and limit share one unit. The calculator does not auto-convert between units, which helps prevent accidental mixed-unit submissions.
6) Can I keep a record of multiple options?
Yes. Each successful check is saved in session history. Run alternative scenarios, then export CSV or PDF to share with reviewers and the project team.
7) The tool shows non-compliant—what is the fastest fix?
Check the “Max allowable proposed height” value, then adjust roof datum, parapet, equipment height, or clearance until the effective height falls below the limit with margin.