By The Roofing Brief Team. Last reviewed: October 2026.
Cool roof requirements now apply in nine US codes tracked here, and the binding number in almost every one is the roof’s solar reflectance. For low-slope roofs the floor runs from a 3-year aged solar reflectance of 0.55 under IECC 2021 Section C402.3 to an initial 0.72 under Chicago Building Code 14B-15-1515, so a compliant flat roof must reflect at least 55 to 72 percent of incoming sunlight. California’s Title 24 is the only mandate that reaches re-roofs on existing single-family homes statewide (2025 Energy Code, effective January 1, 2026), and Atlanta’s Ordinance 25-O-1310 adds aged thresholds of 0.70 low-slope and 0.21 steep-slope from June 2026.
Every threshold below is cited to a named code section, ordinance or agency summary, with the effective date where the code states one.
Headline finding: the cool roof mandate map is small, urban, and built on one number
Reflective-roof mandates in the United States are concentrated in hot-climate states and dense cities, they overwhelmingly target low-slope commercial roofs, and nearly all of them hinge on a solar reflectance threshold rather than material type. Of the jurisdictions tracked here, Chicago (0.72 initial), New York City (0.70 initial), Atlanta (0.70 aged, from June 2026) and Philadelphia (0.65 initial) impose the highest low-slope reflectance floors, while California’s Title 24 (aged 0.63 for low-slope) is the widest in scope because it applies statewide to residential and nonresidential re-roofing in most climate zones.
In these places roof color is a code item. A black PVC membrane reflects only 0.04 to 0.05 of sunlight and a black or dark brown asphalt shingle 0.04 to 0.15, per Table 2 of the EPA Reducing Urban Heat Islands compendium, Cool Roofs chapter (2008), so a dark shingle or dark membrane on a covered roof fails any threshold above 0.15 unless an exemption applies.
What counts as a cool roof, and why solar reflectance is the number that matters
A cool roof is a roof surface engineered to reflect more sunlight and shed absorbed heat, measured by two radiative properties: solar reflectance (the fraction of solar energy reflected, from 0 to 1) and thermal emittance (how efficiently the surface releases absorbed heat, from 0 to 1), per the Cool Roof Rating Council (CRRC, 2026). Codes usually also cite the Solar Reflectance Index (SRI), a combined 0-to-100+ scale defined by ASTM E1980.
Reflectance is the number that carries most mandates because it governs how much heat the roof absorbs in the first place. The CRRC rates products for both initial values and values aged three years at outdoor test farms in Arizona, Ohio, and Florida, because reflectance degrades from soiling, biological growth, and UV exposure (CRRC, 2026). That is why some codes cite a lower aged threshold alongside a higher initial one: a fresh white membrane near 0.80 reflectance can weather down toward 0.55 within three years. Reflectance also drives the energy-efficient roof color choices building owners weigh even where no mandate applies.
Which US cities and states mandate reflective roofs (2026 tracker)
Nine tracked mandates are ranked here by low-slope stringency, using the initial solar reflectance floor where a code sets one and the aged value where it does not. Thresholds, scope, and effective dates are drawn from each jurisdiction’s code, the CRRC codes database and the Smart Surfaces Policy Tracker. “Low-slope” means a roof pitch under 2:12, where most cool roof rules concentrate.
| Jurisdiction | Low-slope reflectance requirement | Steep-slope requirement | Scope | In force since | Source (year) |
|---|---|---|---|---|---|
| Chicago, IL | Initial SR ≥ 0.72, or 3-year aged SR ≥ 0.50 | Initial SR ≥ 0.15 on roofs other than low-sloped; exempt at 5:12 or steeper and on historic buildings | New roof coverings, including recovers and replacements | 2009 (low-slope rule); current text amended 2022 | Chicago Building Code 14B-15-1515; CRRC (2026) |
| New York City, NY | Initial SR ≥ 0.70 and TE ≥ 0.75, or SRI ≥ 82; 75% of roof area | Initial SR ≥ 0.25 or SRI ≥ 39 | New and substantially renovated low-slope roofs | 2009, expanded 2011 | NYC Energy Conservation Code; Smart Surfaces Policy Tracker (2024) |
| Atlanta, GA | 3-year aged SR ≥ 0.70 and aged SRI ≥ 85 | 3-year aged SR ≥ 0.21 and aged SRI ≥ 20 | New and replacement roofs; tracker lists all building types, Georgia Tech describes commercial roofs | Passed June 2, 2025; effective June 2026 | Ordinance 25-O-1310; Smart Surfaces Policy Tracker (2026) |
| Philadelphia, PA | Initial SR ≥ 0.65; 3-year aged SRI ≥ 64 or initial SRI ≥ 82 | Not mandated (low-slope focus) | New buildings, additions, and roof rebuilds over conditioned low-slope space | 2010 | Philadelphia Energy Efficiency Regulation 17-111 (2020) |
| California (statewide, Title 24) | Aged SR ≥ 0.63 and TE ≥ 0.75, or SRI ≥ 75 (nonresidential: all climate zones; single-family re-roof: zones 4 and 6 to 15) | Single-family re-roof: aged SR ≥ 0.20 and TE ≥ 0.75, or SRI ≥ 16 (climate zones 4 and 8 to 15) | New construction, additions, and alterations including re-roofing; residential and nonresidential | 2025 code, effective Jan 2026 | 2025 Energy Code Sections 141.0(b)2B and 150.2(b)1I, per the CRRC 2025 code summary |
| ASHRAE 90.1 (model code) | Aged SR ≥ 0.55 and TE ≥ 0.75, or SRI ≥ 64 (climate zones 0-3) | Not mandated | Commercial low-slope roofs where the standard is adopted | Varies by state adoption | ANSI/ASHRAE/IES 90.1; CRRC (2026) |
| Los Angeles, CA (city) | SRI ≥ 78 (Smart Surfaces Policy Tracker); vegetated and solar roofs exempt | SRI ≥ 20 (tracker); aged SR ≥ 0.25 after the 2018 update | New residential low-rise construction | 2014, tightened 2018 | LA Ordinance 183149; Smart Surfaces Policy Tracker (2024) |
| Denver, CO | Cool roof (SRI thresholds) plus one additional green measure | Not separately mandated | New buildings and re-roofs on buildings 25,000 sq ft and larger | 2018-2019 | Denver Green Buildings Ordinance (2019) |
| Texas metros (IECC 2021) | 3-year aged SR ≥ 0.55 and aged TE ≥ 0.75, or aged SRI ≥ 64, over cooled space (climate zones 0 to 3) | Not required (C402.3 covers low-sloped roofs only) | New construction in adopting cities (Houston, Dallas, others) | 2021 code adoption | IECC 2021 Section C402.3 and Table C402.3 |
Chicago and New York set the strictest reflectance floors
Chicago imposes the highest single initial reflectance requirement of any tracked jurisdiction: low-slope roof coverings must have an initial reflectance of at least 0.72, or a three-year aged reflectance of at least 0.50 (Chicago Building Code 14B-15-1515.2.1, a rule the city first adopted in 2009). Chicago also sets a floor for pitched roofs: coverings on roofs other than low-sloped need an initial reflectance of 0.15 or greater, unless the roof slope is 5:12 or steeper or the building is historic (14B-15-1515.2.2). Our Illinois cost guide covers Chicago cool roof rules on a residential reroof. New York City is close behind, requiring an initial solar reflectance of 0.70 with thermal emittance of at least 0.75, or an SRI of 82, across at least 75 percent of a new or substantially renovated low-slope roof (NYC Energy Conservation Code; Smart Surfaces Policy Tracker, 2024).
Both cities carve out exemptions. Chicago lowers the requirement for the rest of a low-slope roof to a three-year aged reflectance of 0.30 where more than half the roof area is a vegetative roof or roof garden, and for roofs fully ballasted at 15 pounds per square foot or more (Chicago Building Code 14B-15-1515.2.1). The IECC 2021 model code exempts roof portions ballasted with at least 17 psf of stone or 23 psf of pavers, plus areas under PV, vegetative roofs and rooftop equipment (Section C402.3, exceptions 1 and 3). These are heat-island rules first: the stated purpose is to cut rooftop surface temperatures in dense, paved urban cores.
California’s Title 24 is the widest-reaching mandate
California’s Title 24, Part 6 energy code is the only mandate tracked here that applies statewide and reaches re-roofing on existing single-family homes, not just new commercial construction. The 2025 code, effective January 1, 2026, sets the low-slope threshold at an aged solar reflectance of at least 0.63 and thermal emittance of at least 0.75, or an SRI of 75. Where that applies depends on the building: nonresidential low-slope re-roofs in every climate zone (Section 141.0(b)2Bi), single-family low-slope re-roofs in climate zones 4 and 6 through 15 (Section 150.2(b)1Iii), and multifamily low-slope alterations in zones 2, 4 and 6 through 15 (Section 180.2(b)1Ai), per the Cool Roof Rating Council summary of the 2025 Energy Code.
Steep-slope re-roofs on single-family homes face a lower but still binding threshold: an aged solar reflectance of at least 0.20 and thermal emittance of at least 0.75, or an SRI of 16, in climate zones 4 and 8 through 15 (Section 150.2(b)1Ii, per the CRRC summary). The section covers re-roofing by replacement, recovering or re-coating, so a California homeowner re-roofing in a covered zone may be required to install a rated cool product. The prescriptive path lists equivalent options, including ceiling insulation of at least R-38 (or a ceiling U-factor of 0.025 or lower), a qualifying attic radiant barrier, R-2 or greater continuous insulation at the roof deck, or, in climate zones 2, 4, 9, 10, 12 and 14, no ducts in the attic. Roofs weighing at least 25 lb/ft2 are exempt, and the performance-compliance path remains an alternative. Higher steep-slope figures (0.25 aged reflectance or SRI 23 in zones 10, 11, 13 and 15) appear in one multifamily new-construction option under Section 170.2(a)1A; they do not apply to single-family re-roofs. For how these rules show up in a project budget, see Title 24 cool roof rules on a California re-roof.
Where reflective roofs are not required
Most of the United States has no cool roof mandate at all. Outside California’s statewide code and the named cities, reflective-roof requirements generally appear only where a jurisdiction has adopted ASHRAE 90.1 or the IECC commercial provisions, a patchwork documented in our state roofing code and licensing report, which apply cool roof rules to low-slope commercial roofs in the hottest climate zones (0 through 3) and leave steep-slope residential roofs largely unregulated (ANSI/ASHRAE/IES 90.1; CRRC, 2026).
Cold-climate states rarely mandate reflectivity because a reflective roof can raise winter heating demand, the “heating penalty.” IECC 2021 Section C402.3 applies only in climate zones 0 through 3, and the DOE and Lawrence Berkeley National Laboratory cool roof fact sheet notes that winter penalties can be smaller than summer savings even in mixed climates, with a white commercial roof saving up to $0.20 per sq ft a year.
Which cool roof meets which requirement
| If your project is… | Minimum to clear | Rule or source |
|---|---|---|
| A low-slope re-roof in Chicago | Initial SR 0.72, or 3-year aged SR 0.50; check the CRRC label, because white PVC tests 0.70 to 0.78 initial in EPA Table 2 | Chicago Building Code 14B-15-1515.2.1 |
| A low-slope roof over cooled space in an IECC 2021 jurisdiction, climate zones 0 to 3 | 3-year aged SR 0.55 and aged TE 0.75, or aged SRI 64 | IECC 2021 Table C402.3 |
| A low-slope roof ballasted with 17 psf of stone or more (IECC) or 15 psf or more (Chicago) | Exempt under IECC; Chicago drops the rest of the roof to aged SR 0.30 | IECC C402.3 exception 3; Chicago 14B-15-1515.2.1 |
| A single-family steep-slope re-roof in California climate zones 4 or 8 to 15 | Aged SR 0.20 and TE 0.75, or SRI 16, unless an equivalent option (such as R-38 ceiling insulation) or a roof of 25 lb per sq ft or more applies | Title 24 Section 150.2(b)1Ii |
| A new or replacement roof in Atlanta from June 2026 | Low slope: aged SR 0.70 and aged SRI 85; steep slope: aged SR 0.21 and aged SRI 20 | Ordinance 25-O-1310 |
| A steep-slope roof in a cold-climate state outside these cities | No reflectance minimum under IECC C402.3; product choice is open | IECC 2021 Section C402.3 (climate zones 0 to 3 only) |
Typical reflectance and installed-cost ranges for common roof surfaces come from Table 2 of the same EPA compendium chapter (2008), which reprints a 2006 cost study. Treat the dollar figures as 2006 prices for comparing options, not as current quotes.
| Roof surface | Solar reflectance | Thermal emittance | Cost range in the study ($/sq ft) | Clears a 0.55 aged low-slope floor? |
|---|---|---|---|---|
| Black PVC single-ply | 0.04 to 0.05 | 0.80 to 0.90 | 1.0 to 2.0 | No |
| White PVC single-ply | 0.70 to 0.78 | 0.80 to 0.90 | 1.0 to 2.05 | Often, if the aged CRRC value holds 0.55 or more |
| Built-up roof, smooth surface with white coating | 0.75 to 0.85 | 0.80 to 0.90 | 1.2 to 2.15 | Often, if the aged CRRC value holds 0.55 or more |
| Modified bitumen, white coating over mineral cap | 0.60 to 0.75 | 0.80 to 0.90 | 1.5 to 1.95 | Marginal; check the aged value |
| Metal, white painted | 0.60 to 0.70 | 0.80 to 0.90 | 1.8 to 3.75 | Marginal; check the aged value |
| Asphalt shingle, black or dark brown | 0.04 to 0.15 | 0.80 to 0.90 | 0.5 to 2.0 | No (steep-slope products are judged against 0.15 to 0.25 floors) |
| Asphalt shingle, “white” (light gray) | 0.25 to 0.27 | 0.80 to 0.90 | 0.6 to 2.1 | No; it can clear steep-slope floors of 0.20 to 0.21 only if its aged value holds |
The same EPA chapter puts cool roof coatings at $0.75 to $1.50 per sq ft installed and single-ply membranes at $1.50 to $3.00 per sq ft, with a cool premium of zero to 5 or 10 cents per sq ft for most products. The DOE and LBNL fact sheet says cool asphalt shingles sold for up to $0.50 per sq ft more than conventional shingles when it was published.
What a compliant cool roof looks like on the job
On a low-slope commercial roof, compliance usually means a white or light-gray single-ply membrane (TPO or PVC), a reflective coating over an existing membrane, or a light-colored modified-bitumen cap sheet, all carrying a CRRC product label that documents the rated reflectance and emittance. The label is what an inspector checks against the code threshold (CRRC, 2026).
- Identify the roof slope and climate zone. Under 2:12 pitch triggers the stricter low-slope thresholds; the climate zone determines whether the rule applies at all.
- Match a CRRC-rated product to the local threshold. Compare the product’s aged reflectance and emittance (or SRI) to the jurisdiction’s minimum before ordering.
- Confirm the compliance path. Title 24 and IECC 2021 both offer a prescriptive reflectance path and a performance (energy-model) path; in California the prescriptive path also accepts equivalents such as R-38 ceiling insulation on a single-family steep-slope re-roof.
- Document for inspection. Keep the CRRC label and product data on site; the reflectance value on the label is the number that clears or fails the roof.
Methodology
This tracker compiles reflective-roof mandates in force as of October 2026 from primary regulatory sources: the California Energy Commission’s Title 24 Part 6 standards, municipal energy and building codes for Chicago, New York City, Philadelphia, Los Angeles, and Denver, the ANSI/ASHRAE/IES Standard 90.1 model energy standard, and the International Energy Conservation Code (IECC) 2021 Section C402.3, and Atlanta Ordinance 25-O-1310. Threshold values were cross-checked against the Cool Roof Rating Council codes and programs database (2026) and the Smart Surfaces Policy Tracker (2026). Reflectance and cost ranges by surface come from the EPA heat island compendium (2008). Jurisdictions are ranked by low-slope stringency using each code’s stated solar reflectance floor, preferring the initial value where a code specifies one and the aged value where it does not. Solar reflectance, thermal emittance, and SRI are defined per CRRC and ASTM E1980.
Limitations
This is a non-exhaustive snapshot, not a legal compliance opinion. Additional local jurisdictions maintain cool roof provisions that are not individually listed here, and codes change: adoption dates, climate-zone assignments, and threshold values are periodically revised, so a given city may have amended its rule after October 2026. Many mandates include exemptions (green roofs, high-rise buildings, rooftop equipment, historic structures) and offer a performance-based compliance alternative that can permit a non-reflective roof when whole-building energy targets are met. Requirements vary by roof slope, climate zone, building type, and whether the work is new construction or re-roofing. Building owners and contractors should confirm the current requirement with the local authority having jurisdiction before specifying a roof.
Frequently asked questions
Which US cities require cool or reflective roofs?
As of October 2026, cool roof requirements are in force in New York City, Chicago, Philadelphia, Los Angeles, Denver and Atlanta (effective June 2026), plus statewide in California under Title 24. Most rules apply to low-slope roofs. Other cities enforce reflectance indirectly by adopting IECC 2021 Section C402.3, which covers low-slope roofs over cooled space in climate zones 0 through 3.
What solar reflectance does a cool roof code require?
For low-slope roofs, tracked mandates require an initial solar reflectance of 0.65 to 0.72 (Philadelphia 0.65, New York City 0.70, Chicago 0.72) or a 3-year aged reflectance of 0.55 to 0.70 (IECC 2021 and ASHRAE 90.1 at 0.55, California Title 24 at 0.63, Atlanta at 0.70). Steep-slope floors are lower, an aged reflectance of 0.20 to 0.25, per each jurisdiction’s code.
Does California require a cool roof when I replace my roof?
In many cases, yes. California’s 2025 Title 24 covers re-roofing by replacement, recovering or re-coating, so re-roofing an existing home in a covered climate zone (zones 4 and 6 to 15 for low-slope; 4 and 8 to 15 for steep-slope, per Section 150.2(b)1I) may require a CRRC-rated product meeting the aged reflectance or SRI minimum. Equivalent options such as R-38 ceiling insulation and a performance path exist, so confirm with your local building department.
Do dark shingles violate cool roof codes?
They can, on a roof the code covers. EPA’s heat island compendium lists black or dark brown asphalt shingles at a solar reflectance of 0.04 to 0.15, below the 0.20 aged steep-slope floor in Title 24 and the 0.21 floor in Atlanta. A dark-colored shingle complies only if it is a CRRC-rated cool product that meets the aged value, or if the project uses an equivalent option or the performance path.
What is the difference between solar reflectance and SRI?
Solar reflectance is the fraction of sunlight a surface reflects, from 0 to 1. The Solar Reflectance Index (SRI), defined by ASTM E1980, combines reflectance and thermal emittance into one 0-to-100+ scale that estimates relative surface temperature. IECC 2021 Table C402.3, for example, accepts either an aged reflectance of 0.55 with emittance of 0.75 or an aged SRI of 64.
Why do cool roof mandates concentrate in hot cities?
Reflective roofs cut summer heat gain; the DOE and LBNL fact sheet says a cool roof can reduce a single-story building’s annual air-conditioning energy use by up to 15%. In cold climates a reflective roof can raise winter heating demand, so IECC 2021 Section C402.3 applies only in climate zones 0 through 3, and mandates cluster in southern states and dense urban cores.