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Climate zones from Figure R301.1 or Table R301.1 shall be used in determining the applicable requirements from Chapter 4.


Warm and Humid counties are below the dashed white line
FIGURE R301.1
NORTH CAROLINA CLIMATE ZONES




TABLE R301.1
NORTH CAROLINA CLIMATE ZONES, MOISTURE REGIMES, AND WARM-HUMID DESIGNATIONS BY COUNTY
Key: A — Moist.
Asterisk (*) indicates a warm-humid location.
NORTH CAROLINA
4A Alamance
4A Alexander
5A Alleghany
3A Anson
5A Ashe
5A Avery
3A Beaufort
4A Bertie
3A Bladen
3A Brunswick*
4A Buncombe
4A Burke
3A Cabarrus
4A Caldwell
3A Camden
3A Carteret*
4A Caswell
4A Catawba
4A Chatham
4A Cherokee
3A Chowan
4A Clay
4A Cleveland
3A Columbus*
3A Craven
3A Cumberland
3A Currituck
3A Dare
3A Davidson
4A Davie
3A Duplin
4A Durham
3A Edgecombe
4A Forsyth
4A Franklin
3A Gaston
4A Gates
4A Graham
4A Granville
3A Greene
4A Guilford
4A Halifax
4A Harnett
4A Haywood
4A Henderson
4A Hertford
3A Hoke
3A Hyde
4A Iredell
4A Jackson
3A Johnston
3A Jones
4A Lee
3A Lenoir
4A Lincoln
4A Macon
4A Madison
3A Martin
4A McDowell
3A Mecklenburg
5A Mitchell
3A Montgomery
3A Moore
4A Nash
3A New Hanover*
4A Northampton
3A Onslow*
4A Orange
3A Pamlico
3A Pasquotank
3A Pender*
3A Perquimans
4A Person
3A Pitt
4A Polk
3A Randolph
3A Richmond
3A Robeson
4A Rockingham
3A Rowan
4A Rutherford
3A Sampson
3A Scotland
3A Stanly
4A Stokes
4A Surry
4A Swain
4A Transylvania
3A Tyrrell
3A Union
4A Vance
4A Wake
4A Warren
3A Washington
5A Watauga
3A Wayne
4A Wilkes
3A Wilson
4A Yadkin 
5A Yancey
Warm humid counties are identified in Table R301.1 by an asterisk.
Deleted. Tables R301.3(1) and Table R301.3(2) contain no NC requirements but are retained for information only.
TABLE R301.3(1)
INTERNATIONAL CLIMATE ZONE DEFINITIONS
MAJOR CLIMATE TYPE DEFINITIONS
Marine (C) Definition—Locations meeting all four criteria:
1. Mean temperature of coldest month between -3°C (27°F) and 18°C (65°F).
2. Warmest month mean < 22°C (72°F).
3. At least four months with mean temperatures over 10°C (50°F).
4. Dry season in summer. The month with the heaviest precipitation in the cold season has at least three times as much precipitation as the
month with the least precipitation in the rest of the year. The cold season is October through March in the Northern Hemisphere and
April through September in the Southern Hemisphere.
Dry (B) Definition—Locations meeting the following criteria:
Not marine and Pin < 0.44 × (TF - 19.5) [Pcm < 2.0 × (TC + 7) in SI units]
where:
Pin = Annual precipitation in inches (cm)
T = Annual mean temperature in °F (°C)
Moist (A) Definition—Locations that are not marine and not dry.
Warm-humid Definition—Moist (A) locations where either of the following wet-bulb temperature conditions shall occur during the warmest
six consecutive months of the year:
1. 67°F (19.4°C) or higher for 3,000 or more hours; or
2. 73°F (22.8°C) or higher for 1,500 or more hours.
For SI: °C = [(°F)-32]/1.8, 1 inch = 2.54 cm.


TABLE R301.3(2)
INTERNATIONAL CLIMATE ZONE DEFINITIONS
ZONE
NUMBER
THERMAL CRITERIA
IP Units SI Units
1 9000 < CDD50°F 5000 < CDD10°C
2 6300 < CDD50°F ≤ 9000 3500 < CDD10°C ≤ 5000
3A and 3B 4500 < CDD50°F ≤ 6300 AND HDD65°F ≤ 5400 2500 < CDD10°C ≤ 3500 AND HDD18°C ≤ 3000
4A and 4B CDD50°F ≤ 4500 AND HDD65°F ≤ 5400 CDD10°C ≤ 2500 AND HDD18°C ≤ 3000
3C HDD65°F ≤ 3600 HDD18°C ≤ 2000
4C 3600 < HDD65°F ≤ 5400 2000 < HDD18°C ≤ 3000
5 5400 < HDD65°F ≤ 7200 3000 < HDD18°C ≤ 4000
6 7200 < HDD65°F ≤ 9000 4000 < HDD18°C ≤ 5000
7 9000 < HDD65°F ≤ 12600 5000 < HDD18°C ≤ 7000
8 12600 < HDD65°F 7000 < HDD18°C
For SI: °C = [(°F)-32]/1.8.
The interior design temperatures used for heating and cooling load calculations shall be a maximum of 72°F (22°C) for heating and minimum of 75°F (24°C) for cooling.
Materials, systems and equipment shall be identified in a manner that will allow a determination of compliance with the applicable provisions of this code.
An R-value identification mark shall be applied by the manufacturer to each piece of building thermal envelope insulation 12 inches (305 mm) or greater in width. Alternately, the insulation installers shall provide a certification listing the type, manufacturer and R-value of insulation installed in each element of the building thermal envelope. For blown or sprayed insulation (fiberglass and cellulose), the initial installed thickness, settled thickness, settled R-value, installed density, coverage area and number of bags installed shall be listed on the certification. For sprayed polyurethane foam (SPF) insulation, the installed thickness of the areas covered and R-value of installed thickness shall be listed on the certification. For insulated siding, the R-value shall be labeled on the product's package and shall be listed on the certification. The insulation installer shall sign, date and post the certification in a conspicuous location on the job site.
The thickness of blown-in or sprayed roof/ceiling insulation (fiberglass or cellulose) shall be written in inches (mm) on markers that are installed at least one for every 300 square feet (28 m2) throughout the attic space. The markers shall be affixed to the trusses or joists and marked with the minimum initial installed thickness with numbers not less than 1 inch (25 mm) in height. Each marker shall face the attic access opening. Spray polyurethane foam thickness and installed R-value shall be listed on certification provided by the insulation installer.
Insulating materials shall be installed such that the manufacturer's R-value mark is readily observable upon inspection.
U-factors of fenestration products (windows, doors and skylights) shall be determined in accordance with NFRC 100. U-factors shall be determined by an accredited, independent laboratory, and labeled and certified by the manufacturer. Products lacking such a labeled U-factor shall be assigned a default U-factor from Table R303.1.3(1) or R303.1.3(2). The solar heat gain coefficient (SHGC) and visible transmittance (VT) of glazed fenestration products (windows, glazed doors and skylights) shall be determined in accordance with NFRC 200 by an accredited, independent laboratory, and labeled and certified by the manufacturer. Products lacking such a labeled SHGC or VT shall be assigned a default SHGC or VT from Table R303.1.3(3).

Exception: When a garage door is a part of the building thermal envelope, garage door U-factors shall be determined in accordance with either NFRC 100 or ANSI/DASMA 105.

TABLE R303.1.3(1)
DEFAULT GLAZED FENESTRATION U-FACTORS
FRAME TYPE SINGLE
PANE
DOUBLE
PANE
SKYLIGHT
Single Double
Metal 1.20 0.80 2.00 1.30
Metal with Thermal Break 1.10 0.65 1.90 1.10
Nonmetal or Metal Clad 0.95 0.55 1.75 1.05
Glazed Block 0.60


TABLE R303.1.3(2)
DEFAULT DOOR U-FACTORS
DOOR TYPE U-FACTOR
Uninsulated Metal 1.20
Insulated Metal 0.60
Wood 0.50
Insulated, nonmetal edge, max 45% glazing,
any glazing double pane
0.35


TABLE R303.1.3(3)
DEFAULT GLAZED FENESTRATION SHGC AND VT
SINGLE GLAZED DOUBLE GLAZED GLAZED
BLOCK
Clear Tinted Clear Tinted
SHGC 0.8 0.7 0.7 0.6 0.6
VT 0.6 0.3 0.6 0.3 0.6
The thermal resistance (R-value) of insulation shall be determined in accordance with the U.S. Federal Trade Commission R-value rule (CFR Title 16, Part 460) in units of h ft2 °F/Btu at a mean temperature of 75°F (24°C).
The thermal resistance (R-value) of insulated siding shall be determined in accordance with ASTM C 1363. Installation for testing shall be in accordance with the manufacturer's instructions.
Materials, systems and equipment shall be installed in accordance with the manufacturer's instructions and the International Building Code or International Residential Code, as applicable.
Insulation applied to the exterior of basement walls, crawlspace walls and the perimeter of slab-on-grade floors shall have an opaque and weather-resistant protective covering to prevent the degradation of the insulation's thermal performance. The protective covering shall cover the exposed exterior insulation and extend not less than 6 inches (153 mm) below grade.
Maintenance instructions shall be furnished for equipment and systems that require preventive maintenance.