Class A Roofs in Hawaii: What the New Wildfire Roofing Standards Mean for Island Property Owners
Hawaii is not exempt from wildfire risk. The August 2023 Lahaina fire demonstrated how quickly wind-driven fire can move through developed communities. Wildfire exposure also exists in wildland-urban interface areas and dry, leeward, or former agricultural lands on Maui, Hawaii Island, Oahu, and Kauai.
For property owners, the question is not limited to whether a roof is labeled “Class A.” Does the complete roof assembly resist external fire exposure? Are vulnerable edges, vents, gutters, and roof-to-wall transitions protected from embers? Can the system also withstand Hawaii’s wind, rain, ultraviolet radiation, salt air, and, in some areas, volcanic ash?
The answers require a review of the roof assembly, site conditions, applicable county requirements, and maintenance history.
What does a Class A roof rating measure?
Class A is the highest external fire classification commonly used for roof coverings. Under UL 790 and ASTM E108, roof assemblies are exposed to simulated external fire conditions.
The testing evaluates factors such as:
Flame spread across the roof surface
Resistance to fire penetration through the roof covering and deck
Performance when exposed to a standardized burning brand
Production of flying brands or embers
Stability of the roof covering during the test
A Class A rating therefore indicates that the tested assembly provides a high level of protection against severe external fire exposure. It does not mean that the roof is fireproof, nor does it certify every possible roof configuration.
The rating applies to the tested assembly. The covering, underlayment, insulation, cover board, deck, fasteners, and installation details may all affect performance. Substituting materials or changing the assembly without confirming the applicable listing can change the result.
A Class A roof also does not automatically mean that the entire building is ember-resistant. The test does not address every condition that can allow embers to enter or ignite a structure.
Class A is not the same as ember-resistant construction
During a wildfire, embers may travel ahead of the main flame front. They can collect in areas where debris accumulates or enter concealed spaces through openings.
Potentially vulnerable locations include:
Roof edges and metal drip edges
Eave and fascia returns
Open soffits and exposed rafter tails
Dormers and roof-to-wall intersections
Valleys and changes in roof direction
Gutters and downspouts
Skylights and curbs
Attic, ridge, and soffit vents
Mechanical penetrations and pipe flashings
A Class A assembly can reduce the likelihood of roof ignition. It does not cover debris accumulation in a gutter, an open soffit vent, combustible material below a roof edge, or an unsealed gap at a wall intersection.
For this reason, roof hardening is generally evaluated as part of a larger building-envelope and home-ignition-zone review. FEMA wildfire guidance identifies roof materials, roof and gutter maintenance, eaves, openings, and exterior construction as related elements of wildfire risk reduction.
Would a property assessment identify these conditions at the roof perimeter, or would it review only the field of the roof covering?
Why are wood shakes and shingles a concern?
Wood shakes and shingles are combustible roof coverings. Some wood products can achieve a Class A rating when treated, installed over a specified fire-resistant substrate, or included in a tested roof assembly. The rating must be confirmed for the specific product and assembly rather than assumed from the material description.
Hawaii’s climate creates additional service-life concerns. Intense ultraviolet exposure, salt air, heavy rain, humidity, and repeated wetting and drying can affect wood, coatings, fasteners, and fire-retardant treatments. The rate of degradation depends on the product, exposure, installation, inspection history, and maintenance.
This creates a practical question for owners: does the current roof still perform as documented when it was installed?
California and Colorado have adopted increasingly restrictive approaches to combustible roofing in designated wildfire-risk areas. Some high-risk jurisdictions restrict or prohibit wood shakes and similar materials, while others require ignition-resistant assemblies and additional detailing. These changes reflect a broader regulatory and insurance trend that Hawaii property owners may encounter as wildfire risk assessments become more detailed.
Hawaii’s statewide building-code framework currently includes the 2018 International Residential Code, 2018 International Building Code, and 2024 NFPA 1 State Fire Code. County amendments, local fire districts, permitting conditions, and future code changes may impose additional requirements. A universal statewide Class A requirement for every property should not be assumed without confirming the current rules for the specific location and occupancy.
Hawaii roofs must address more than wildfire
A roof selected for Hawaii must generally serve multiple performance objectives. These may include:
Wildfire and ember exposure
Hurricane and high-wind conditions
Wind-driven rain
Salt-air corrosion
Intense ultraviolet radiation
Heavy rainfall and drainage demands
Volcanic ash or airborne particulate exposure
Rooftop solar, mechanical equipment, and maintenance traffic
A material that performs well against one hazard may require additional detailing for another. For example, a metal roof may provide a noncombustible surface, but its fasteners, penetrations, coatings, laps, and perimeter securement remain important in a coastal or high-wind environment. Tile may be noncombustible, but loose tiles, open ends, debris beneath tiles, and inadequate edge detailing can create vulnerabilities.
Low-slope systems also require assembly-level review. TPO or other single-ply membranes may achieve Class A as part of a tested assembly, depending on the deck, insulation, cover board, attachment method, and listing. The membrane alone is not sufficient evidence of the assembly rating.
Common roof options for Hawaii properties
The appropriate roof system depends on slope, occupancy, wind exposure, coastal conditions, fire risk, budget, and maintenance access.
Standing-seam metal
Standing-seam metal can provide a noncombustible roof surface and is commonly considered for residential, commercial, hospitality, and industrial buildings. Review should include:
Panel and clip attachment
Perimeter securement
Fastener and flashing compatibility
Corrosion resistance
Penetrations and curbs
Underlayment and deck configuration
Class A assembly documentation
Concrete or clay tile
Concrete and clay tile are noncombustible options frequently used in residential and hospitality construction. The assembly should be reviewed for:
Tile attachment under applicable wind loads
Eave, hip, and ridge detailing
Birdstops or closures
Debris accumulation beneath tiles
Valley and wall intersections
Replacement and maintenance access
Asphalt composition shingles
Fiberglass asphalt composition shingles are available in Class A assemblies and may be appropriate for many sloped roofs. Owners should confirm the product listing, underlayment, deck, slope, fastening pattern, and wind rating. Shingles also require periodic inspection for uplift, loss of granules, seal failure, and damage from weather or maintenance activity.
TPO or other membrane systems
TPO and similar membranes are widely used on low-slope commercial, multifamily, and hospitality roofs. The review should address the complete tested assembly, including insulation, cover board, fasteners, seams, flashings, parapets, curbs, drains, and overflow provisions.
Owner checklist: roof and ember vulnerability
Property owners, developers, and facility managers may use the following checklist as a starting point.
Assembly and design
Confirm whether the complete roof assembly has a Class A listing.
Obtain the applicable UL 790 or ASTM E108 documentation.
Verify that installed components match the tested assembly.
Review the roof deck, underlayment, insulation, cover board, and attachment method.
Confirm local county code, fire district, and permit requirements.
Review roof-to-wall, parapet, curb, skylight, and penetration details.
Confirm that vents and soffits are designed to limit ember entry where appropriate.
Roof condition
Inspect roof edges, fascia returns, eaves, and valleys.
Check gutters and roof drains for combustible debris.
Inspect skylights, curbs, vents, and mechanical penetrations.
Look for damaged, displaced, cracked, or deteriorated roof coverings.
Check metal fasteners, flashings, coatings, and exposed cut edges for corrosion.
Re-seal or repair deteriorated flashing transitions.
Document conditions with dated photographs and written observations.
Insurance and underwriting documentation
Retain roof permits, product data, warranties, assembly listings, and maintenance records.
Document the roof’s installation date and replacement history.
Maintain inspection reports showing the condition of edges, penetrations, gutters, and drainage.
Record completed repairs and the materials used.
Ask the insurer or broker what documentation is required for underwriting or renewal.
Avoid describing a roof as “fireproof” or “ember-proof” unless that language is specifically supported by the applicable documentation.
How Pono Consulting Group can assist
Pono Consulting Group provides roofing systems consulting, building envelope consulting, condition assessments, design assistance, contractor procurement, construction monitoring, quality assurance, and project documentation.
Our work can include visual review, core sampling, assessment of roof penetrations and perimeter conditions, repair or replacement recommendations, construction observations, testing, and closeout documentation. These services support multifamily residential, commercial, industrial, hospitality, and renewable energy projects.
With more than 30 years of combined experience, Pono Consulting Group evaluates roof performance in relation to code, cost, service life, wind, rain, wildfire exposure, and the broader building envelope. For owners considering a new roof, replacement, insurance documentation, or a wildfire-resilience upgrade, would an independent assessment clarify the current condition and the available options?
Hawaii wildfire roofing resources
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