Wall Continuous (Exterior) Insulation in Zone 2 (Hot)
The DOE recommends None required for wall continuous (exterior) insulation in Climate Zone 2 (Hot). This zone has 2,000 heating degree days and 3,500 cooling degree days annually. The typical wall continuous (exterior) cavity depth is 2 inches. States in Zone 2 include Alabama, Arizona, Florida, Georgia, Louisiana and 2 more.
Quick Facts
Insulation Not Required
The DOE does not require wall continuous (exterior) insulation in Climate Zone 2 (Hot). The moderate climate in this zone does not create sufficient temperature differentials across this building component to justify the cost of insulation. However, local building codes may have different requirements, and adding insulation may still provide comfort benefits, noise reduction, and improved indoor air quality. Some utility programs and green building certifications may incentivize or require insulation for this component even in Zone 2.
If you choose to add insulation despite it not being required, even a modest R-5 to R-10 can improve comfort by reducing temperature differences between rooms and eliminating cold or hot spots on surfaces adjacent to unconditioned spaces. The cost of adding insulation during new construction is minimal compared to the total project cost, so many builders include it regardless of the code requirement.
Installation Guidance
Continuous exterior wall insulation is not required by the DOE in Climate Zone 2. The moderate climate in this zone means that thermal bridging through studs does not create sufficient heat loss to justify the added cost and complexity of continuous exterior insulation. However, adding continuous insulation during a re-siding project is still beneficial and may be required by local energy codes or incentivized by utility programs. Even R-2 to R-4 of continuous insulation improves comfort by eliminating cold spots on interior wall surfaces aligned with studs and reduces the risk of condensation within the wall cavity.
States in Zone 2
The following states include areas within Climate Zone 2. Click any state to see its complete insulation requirements across all applicable zones.