Roof overhangs: south = 1.5-2× window height (passive solar cutoff); east/west minimal use
ROT/EXT-OVERHANG-BY-ORIENTATIONDescription
South-facing roof overhangs sized to block the summer sun while admitting winter sun: overhang depth ≈ window height ÷ tan(latitude + 23.45 + small adjustment). Practically: 1.5-2× window height at NY latitudes. East + west overhangs offer minimal solar control (low-angle sun comes in horizontally) — better to use shade trees, vertical fins, or low-SHGC glazing on these orientations. North overhangs: minimal solar value; size for rain protection only (18-24 in typical).
Why this exists
Properly-sized south overhangs are the most reliable passive-solar shading strategy. They're free architectural performance — same construction cost, dramatic comfort difference.
Categories
Source
Solver enforcement
Browsable only — the solver does not currently enforce this directive (no spec-level data to check against). This entry exists so the architect personas can cite it in conversation and the user can read what the rule says.
Related directives
- Living spaces south-facing in cold climates · LIVING-SOUTH-FACING
- Kitchen east-facing for breakfast · KITCHEN-EAST-FACING
- Studio / office north-facing for consistent light · STUDIO-NORTH-FACING
- Outdoor connection from main living · BACK-DOOR-FROM-LIVING
- Deck adjacent to kitchen / dining · DECK-RELATIONSHIP
Last reviewed 2026-05-15.