Continuous air barrier on all six sides of conditioned space — including rim joists, knee walls, attic floor
ENERGY STAR SFNH §Air Barrier — continuous on all six sides of every conditioned spaceDescription
An air-tight, continuous air barrier must be installed at every boundary between conditioned and unconditioned space — including walls (drywall + sealed sheathing), rim joists (rigid foam + sealant), attic floor or sloped ceiling (depending on vented vs unvented attic), and any kneewall behind a finished room. Sealing details at every penetration: top plates, recessed lights, plumbing/electrical, attic hatch, fireplace surround.
Why this exists
Air leakage is THE largest avoidable energy loss in residential. The 6-sided continuous air barrier is a design AND construction discipline: the architect draws it; the contractor builds it; the rater verifies it via a blower-door test (typically targeting ≤ 3.0 ACH50 for ENERGY STAR). Architects designing complex transitions (bay windows, tray ceilings, cathedrals) MUST detail the air-barrier path explicitly.
Measurements
| Property | Operator | Value | Unit | Note |
|---|---|---|---|---|
typicalACH50 | max | 3 | ACH50 | Typical ENERGY STAR air-leakage target (varies by climate zone) |
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.