Bulk water management: site drainage 6 in/10 ft away, capillary break above foundation, drainage plane behind cladding
Indoor airPLUS §Moisture Control — bulk water managementDescription
Indoor airPLUS requires bulk-water management at every envelope boundary: site graded ≥ 6 in fall in the first 10 ft (5%) away from the foundation; gutters + downspouts discharging ≥ 5 ft from foundation; capillary break (sill seal, rigid foam, sheet membrane) above the foundation wall; drainage plane behind ALL exterior cladding (rain-screen detail required for stone / brick / large-format claddings); flashing at all wall penetrations.
Why this exists
Water in walls + foundations is the #1 trigger of mold + IAQ problems. The airPLUS bulk-water rules are the architect's design checklist for keeping water OUT of the assembly. Combined with the ENERGY STAR water-management items, this is the most comprehensive residential moisture-protection spec available for free.
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 2026-05-15.