| Primary value | 3.0 × 3.0 m |
| Applies to | Internal courtyards in low-rise buildings · Light wells for ventilation |
| Exceptions | Buildings 12.5–18 m height → 3.6 × 3.6 m typical |
| Measured as | Minimum clear plan dimensions of the courtyard. Larger sizes required for taller buildings to maintain light/ventilation ratio. |
| Source | NBC 2016 — Part 3 ✓ Verified |
Internal courtyards bring natural light and ventilation to interior rooms that can't reach an external wall. The 3 × 3 m minimum is the smallest size that delivers usable daylight to ground floor rooms — anything smaller becomes a vent shaft.
Common in narrow urban plots and shophouse typologies. Modern apartments use cut-outs and double-height living rooms to achieve similar light penetration.