Roof overhangs protect walls — 12-24 inches in humid climates; one foot per story below
HUD RSDG §5.6.5Description
Roof overhangs at the eave and rake protect walls from rain and shade windows from direct sun. As a reasonable design guideline (in many homes none is provided): protective overhang widths should be 12-24 inches in humid climates, with more where practicable. A rule of thumb is to provide a minimum of 12 inches of overhang per story of protected wall below. However, overhang width significantly INCREASES wind uplift load on a roof; in high-wind areas, keep overhangs shorter or detail the framing connections (especially rake overhangs) for the uplift.
Why this exists
The HUD Prevention and Control of Decay in Homes study (1978) correlated climate index with overhang width and showed wall service life extends materially with adequate overhangs. Conflict with high-wind uplift requirements: in coastal zones the FEMA minimal-overhang guidance dominates (see fema-p-2325-minimize-roof-overhangs-wind).
Measurements
| Property | Operator | Value | Unit | Note |
|---|---|---|---|---|
humidClimateMin | min | 12 | in | Minimum overhang in humid climates |
humidClimateMax | exact | 24 | in | Typical upper end of recommended overhang |
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
- Continuous load path from roof to foundation · HUD RSDG §2.4
- Residential structural reliability targets 1-in-100 to 1-in-1000 annual probability of failure · HUD RSDG §2.5
- Residential floor live load: 40 psf minimum (30 psf sleeping rooms) · HUD RSDG §3.4
- Wind load design uses ASCE 7 basic wind speed for the locality · HUD RSDG §3.6
- Ground snow load for Virginia: 25 psf eastern, up to 40 psf western mountains · HUD RSDG §3.7
Last reviewed 2026-05-14.