Building Services Calculators

Stormwater drainage and fire services design aids  ·  AS/NZS 3500.3  ·  AS 2118.1  ·  AS 1670.1  ·  AS/NZS 2293.1  ·  NSB/CSIRO

Four calculators covering the stormwater and fire-services sizing I do most often. Each one works through the governing Australian Standard's own method, cites the clause or figure behind every number, and can print a one-page summary for the project file.

Eaves Gutter & Downpipe Sizing
Size eaves gutters and vertical downpipes from catchment area and design rainfall intensity, including the overflow measures the Standard makes conditional on its rainfall tables. Includes a site-coordinate lookup and BOM IFD link.

AS/NZS 3500.3 2018 & 2025  ·  NSB 151/152/153  ·  CSIRO Technical Paper No. 1

Open calculator →
Fire Sprinkler Spacer
Optimum sprinkler spacing, head count and friction-informed system demand across LH, OH and HH occupancies — plus hung-obstruction clearances for ducts, bulkheads and beams.

AS 2118.1 2017  ·  Cl 5.7 & Table 5.7.2  ·  Hazen–Williams

Open calculator →
Fire Service Spacer — Smoke & Emergency
Optimum spacing and coverage checks for point smoke detectors and emergency luminaires, for early-design layout and feasibility.

AS 1670.1 2024 Cl 5.1  ·  AS/NZS 2293.1 2005 Tables 5.1–5.5

Open calculator →
Box Gutter Sizing
Freely discharging box gutters and all three outlet arrangements — rainhead, side overflow and high-capacity overflow — walked through the Standard's own flow charts, with a printable design summary.

AS/NZS 3500.3 2018 Appendix I  ·  2025 Appendix H

Open calculator →