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InsulationCalculator
Close-up of stacked pink fiberglass batts showing the fiber texture

IECC climate zone 2

Climate Zone 2 — Hot

Hot summers with brief, mild winters. Cooling still dominates, but winter heating is no longer negligible. This zone covers much of the southern US including most of Texas and Florida.

Attic target
R-60recommended level
Wall cavity
R-13wood frame
Floor
R-13over unconditioned space
Example state
TXHouston, TX

Recommended R-values in zone 2

These follow US Department of Energy and ENERGY STAR recommended levels for existing homes. Local building code may require more — check before you start.

Attic

R-60

Minimum R-49

Unlimited depth — the cheapest R-value in the house

Walls

R-13

Capped by framing depth

Floors over unconditioned space

R-13

Matters most over vented crawl spaces

Crawl-space walls

R-10

For sealed, conditioned crawl spaces

Where zone 2 is

States whose most populous area falls in zone 2:

AZFLLATX

Representative cities: Houston, TX · Phoenix, AZ · Orlando, FL · New Orleans, LA.

Several states span three or more zones — California, Texas, Nevada, Arizona, Oregon, Washington, New York, New Mexico, and Idaho among them. Altitude matters as much as latitude. If you are near a boundary,check the map or confirm with your building department.

What insulating costs in zone 2

A 1,240 sq ft attic taken from bare joists to R-60 with blown cellulose, in this zone:

DIY total

$930–$1,650

Material, air sealing, blower, safety gear

Professional

$2,450–$4,950

Includes a 0.95× regional labor adjustment

Material needed

69 bags

17.1" of cellulose

Generated by the same engine as the calculator. Our assumptions.

What matters in this climate

  • Attic insulation pays back fastest on cooling load, not heating
  • Seal and insulate ductwork in the attic — it is a major loss here
  • Spray foam at the roofline is more common here than further north

Other climate zones

Zone 1Cooling runs nearly year-round; heating is almost irrelevant.Zone 3Warm, with short mild winters and a real cooling season.Zone 4Meaningful heating and cooling seasons, roughly balanced.Zone 5Cold winters dominate; heating is the main load.Zone 6Long, cold winters with a short cooling season.Zone 7Severe winters. Maximum insulation is clearly cost-effective.