Free Insulation & Climate-Zone Diagrams
A free set of technical insulation and climate-zone diagrams for writers, educators, and building pros — R-value ladders, wall and roof assemblies, vapor-control placement, thermal bridging, and the IECC climate-zone map. Every figure is drawn to code and cited to its source (2021 IECC, IRC, ASHRAE, ACCA Manual J/S, ASTM, and building-science practice).
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31 free free insulation & climate-zone diagrams · 31 diagrams
- Insulation & Climate
Map of the IECC climate zones across the United States, with climate zone 4 highlighted
IECC climate zones run from warm zone 1 in the south to cold zone 8 in the north. Find your zone — the colder it is, the higher the insulation R-value the code requires.
- Insulation & Climate
How much insulation a house needs in IECC climate zone 4 — attic, walls, and floor
A house needs the most insulation overhead: in climate zone 4 the IECC requires R-60 in the attic, R-30 in the walls, and R-19 in the floor. The thicker the layer, the higher the R-value.
- Insulation & Climate
Map of the eight IECC climate zones across the United States
The IECC divides the country into eight climate zones, warm zone 1 in the south to cold zone 8 in the north. Look up your zone below — the colder it is, the more insulation the code requires.
- Insulation & Climate
Why IECC climate zones are assigned by county, not by state or city
IECC zones are assigned county-by-county (ASHRAE 169), so one state can span two or three zones. The calculator resolves your ZIP to a county, and the county sets your zone.
- Insulation & Climate
IECC minimum attic and wall R-values across all eight climate zones
The colder your zone, the more insulation the code requires — attic minimums climb from R-30 to R-60 and walls from R-13 to R-30, then plateau in the coldest zones.
- Insulation & Climate
What R-value means — the same R-30 takes very different thickness by material
R-value = R-per-inch × thickness. To hit R-30, closed-cell foam needs ~4.6″ but a fiberglass batt needs ~10.3″ — same R, very different depth. Compare materials by R-value, not by inches.
- Insulation & Climate
Thermal bridging — why R-21 batts give you about an R-16 wall
Heat takes the shortcut: the wood studs (≈25% of the wall at 16″ o.c., only ≈R-6.9) bypass the R-21 batt, so the whole-wall R drops to about R-16. Continuous exterior foam covers the studs and breaks the bridge.
- Insulation & Climate
Batt vs. dense-pack vs. spray foam vs. rigid board — what each insulation type does
Same R-value, different jobs: batt must be packed void-free, dense-pack flows around wires and boxes, spray foam also air-seals, and rigid board goes continuous over the studs to break the thermal bridge.
- Insulation & Climate
Open-cell vs. closed-cell spray foam compared in a stud cavity
Closed-cell packs nearly 2× the R per inch of open-cell and adds air, water and vapor control plus rigidity (rim joists, roof decks, below grade). Open-cell is lighter, vapor-open, cheaper per R — but interior-only.
- Insulation & Climate
Spray foam board feet and 2-inch lifts explained
Foam kits are sold in board feet: 1 sq ft × 1 inch = 1 board foot, so board feet = area × thickness. Spray closed-cell in ≤2″ lifts (it cures hot) and budget 70–85% of a kit’s rated yield.
- Insulation & Climate
Unvented roof with spray foam — closed-cell flash, fill, and the thermal barrier
Closed-cell sprayed against the deck makes an unvented, conditioned attic (no soffit/ridge vents). Two code must-dos: the flash coat must hit the R806.5 condensation-control minimum for your zone, and foam in living space needs a ½″ gypsum thermal barrier.
- Insulation & Climate
How attic ventilation works — cool air in at the soffits, hot air out at the ridge
A vented attic is a chimney: cool air enters low at the soffits, sweeps the underside of the deck, and leaves hot at the ridge. It only works when intake (low) and exhaust (high) net free areas are balanced ~50/50.
- Insulation & Climate
Attic vent area math — 1/150 vs 1/300, and why net free area is not the vent size
Required vent area = attic floor ÷ 150 (or ÷ 300 when balanced + a vapor retarder in cold zones), split half intake / half exhaust. Size on Net Free Area — the open area after the screen — not the vent’s gross size.
- Insulation & Climate
The #1 attic mistake — mixing two exhaust types short-circuits the airflow
A ridge vent short-circuits any second exhaust (gable, box/turtle, or a powered fan), starving the soffits and leaving dead air low in the attic. Use ONE exhaust type + continuous soffit intake.
- Insulation & Climate
Why a bigger AC is not better — oversizing short-cycles and leaves the house cold but clammy
Bigger is not better. An oversized AC short-cycles: it cools fast but never runs long enough to dehumidify, so you get a cold, clammy house plus extra compressor wear. A right-sized unit (ACCA Manual S: 95–115% of the load) runs long, steady cycles that stay cool AND dry.
- Insulation & Climate
Where the cooling load comes from — ceiling, walls, windows, air leaks, and internal gains
Square footage only sets the surfaces — the envelope, climate, and windows set how much heat crosses them. On a design day heat enters through the ceiling (biggest — attic ≈ +15°F), walls, windows (conduction + solar), air leaks, and internal gains. Same 2,000 sq ft, leaky vs. tight envelope = very different equipment.
- Insulation & Climate
A heat pump’s balance point — capacity falls as the heating load rises
A heat pump loses capacity exactly as the house needs more heat. Plot both against outdoor temperature and they cross at the balance point. Above it, the heat pump carries the load; below it, backup heat (electric strip or a dual-fuel furnace) covers the gap. A cold-climate unit crosses lower and needs less backup.
- Insulation & Climate
IECC climate zone 1 on the US map (very hot climate)
Climate zone 1 (very hot) covers the southern tip of Florida and Hawaii. Your required insulation depends on this zone.
- Insulation & Climate
Insulation R-values required in IECC climate zone 1 — attic, walls, and floor
What the 2021 IECC requires in climate zone 1: insulation for the attic, walls, and floor. A thicker layer means a higher R-value.
- Insulation & Climate
IECC climate zone 2 on the US map (hot climate)
Climate zone 2 (hot) covers most of Florida, the Gulf Coast, and south Texas. Your required insulation depends on this zone.
- Insulation & Climate
Insulation R-values required in IECC climate zone 2 — attic, walls, and floor
What the 2021 IECC requires in climate zone 2: insulation for the attic, walls, and floor. A thicker layer means a higher R-value.
- Insulation & Climate
IECC climate zone 3 on the US map (warm climate)
Climate zone 3 (warm) covers the Deep South, central Texas, and the low-desert Southwest. Your required insulation depends on this zone.
- Insulation & Climate
Insulation R-values required in IECC climate zone 3 — attic, walls, and floor
What the 2021 IECC requires in climate zone 3: insulation for the attic, walls, and floor. A thicker layer means a higher R-value.
- Insulation & Climate
IECC climate zone 5 on the US map (cool climate)
Climate zone 5 (cool) covers Pennsylvania, New York, Michigan, the upper Midwest, and the interior Northwest. Your required insulation depends on this zone.
- Insulation & Climate
Insulation R-values required in IECC climate zone 5 — attic, walls, and floor
What the 2021 IECC requires in climate zone 5: insulation for the attic, walls, and floor. A thicker layer means a higher R-value.
- Insulation & Climate
IECC climate zone 6 on the US map (cold climate)
Climate zone 6 (cold) covers northern New England, the upper Midwest, and much of the Mountain West. Your required insulation depends on this zone.
- Insulation & Climate
Insulation R-values required in IECC climate zone 6 — attic, walls, and floor
What the 2021 IECC requires in climate zone 6: insulation for the attic, walls, and floor. A thicker layer means a higher R-value.
- Insulation & Climate
IECC climate zone 7 on the US map (very cold climate)
Climate zone 7 (very cold) covers northern Minnesota, far-northern Maine, and high-elevation mountain areas. Your required insulation depends on this zone.
- Insulation & Climate
Insulation R-values required in IECC climate zone 7 — attic, walls, and floor
What the 2021 IECC requires in climate zone 7: insulation for the attic, walls, and floor. A thicker layer means a higher R-value.
- Insulation & Climate
IECC climate zone 8 on the US map (subarctic climate)
Climate zone 8 (subarctic) covers interior Alaska. Your required insulation depends on this zone.
- Insulation & Climate
Insulation R-values required in IECC climate zone 8 — attic, walls, and floor
What the 2021 IECC requires in climate zone 8: insulation for the attic, walls, and floor. A thicker layer means a higher R-value.
Run the numbers
These diagrams pair with the free Insulation Calculator — code-minimum R-values by climate zone, no signup.