Climate Zone 6 (NY Adirondacks, VT, NH, ME, MN, ND): ceiling R-60 / wall R-20+R-5ci OR R-13+R-10ci / basement R-15/19 / slab R-10 (4 ft)
IECC R-value (DOE climate-zone) — CZ 6 Envelope R-values (high-cold)Description
IECC 2021/2024 prescriptive envelope R-values for Climate Zone 6 (Adirondack region of NY, most of VT/NH/ME, northern MN/MI/WI/ND): ceiling R-60; wall R-20 cavity + R-5 continuous, OR R-13 cavity + R-10 continuous (heavy CI strategy); mass walls R-15/19; floor R-30; basement walls R-15 continuous or R-19 cavity; slab-edge R-10 to 4 ft; crawlspace R-15/19. Window U-factor ≤ 0.30.
Why this exists
CZ 6 starts requiring continuous insulation outside the framing — the cavity-only wall isn't enough. Architects working in high-cold climates should default to a CI strategy + spec the cladding fastening accordingly (longer screws, possibly furring strips for rainscreen).
Measurements
| Property | Operator | Value | Unit | Note |
|---|---|---|---|---|
ceiling | min | 60 | R-value | Ceiling R-60 minimum |
wallTotal | min | 25 | R-value effective (R-20 + R-5ci) | Wall R-25 effective minimum |
basementInterior | min | 15 | R-value continuous | Basement wall R-15 continuous |
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
- Habitable space minimum ceiling height · IRC R305.1
- Wind design · IRC R301.2.1
- Seismic provisions · IRC R301.2.2
- Snow loads · IRC R301.2.3
- Floodplain construction · IRC R301.2.4
Last reviewed 2026-05-15.