A Class A roof is a tested assembly, not a fireproof material.
Steep-slope and low-slope roofs · wildland-urban interface
The covering is one layer of three. And the openings around it — vents, eaves, covering voids and gutters — are where the embers that arrive ahead of a wildfire actually get in.
Does a Class A roof protect a house in a wildfire, and what else about the roof matters?
Class A is a fire classification earned by a tested roof assembly — covering, underlayment and deck together — under ASTM E108 or UL 790. Change a layer and you may be outside the listing. It is also not the whole job: wind-blown embers arriving ahead of a fire enter at vents, open eaves, covering voids and debris-filled gutters.
The short versionSection link
The California requirements quoted on this page are quoted because California’s are the most developed and the most publicly documented in the United States — not because they apply where you live. There is no nationwide wildland-urban interface code. Confirm the adopted code, the edition, the amendments and the effective date with your authority having jurisdiction before treating any number here as a requirement.
- What Class A actually is
- A classification for a tested roof assembly, not a property of the coveringThe fire tests behind it are ASTM E108 and UL 790. UL Solutions lists them as three things done to a roof covering specimen: spread of flame, intermittent flame, and burning brand.
- What a real Class A listing names
- Deck, cover board, underlayment, covering, fastener type, fastener spacing, slopeRead a listing from CAL FIRE's own Building Materials Listing and every one of those is written down. The worked example below takes one apart line by line.
- How the fire usually reaches the house
- Wind-blown embers, not a wall of flameIBHS states it flatly: wind-blown embers are the principal cause of building ignitions. NIST calls firebrands a leading cause of structure ignitions in wildland-urban interface fires.
- How far flame alone can ignite a house
- Not beyond about 200 ft, per USDA Forest Service researchJack Cohen, USDA Forest Service: even the large flames of high-intensity crown fires do not directly ignite homes at distances beyond 200 feet. Wall sections at 33 ft ignited in 3 of 7 crown fires; none at 66 ft or 98 ft ignited at all.
- The most vulnerable vent geometry
- A large opening presenting a vertical face to the windIBHS wind-tunnel work: gable-end vents, generic off-ridge vents and vents in open-eave blocking were the poorest performers. Vents in a boxed soffit, and a ridge vent with external baffles, were the best.
- Mesh, where mesh is the rule
- 1/4 in should not be used on any vent; 1/8 in or 1/16 in insteadIBHS's own recommendation. One California jurisdiction's published checklist for the 2019 California Residential Code required vent openings of not less than 1/16 in and not more than 1/8 in, noncombustible and corrosion-resistant.
- The eave rule most people have never heard
- Under the 2019 California residential WUI provisions, vents were generally not permitted on the underside of eavesWith three exceptions — a special eave or cornice vent the enforcing agency accepts, a sprinklered attic, or a noncombustible or ignition-resistant eave underside with the vent more than 12 ft from the ground or a walking surface. That edition was superseded on January 1, 2026 by Title 24 Part 7; section numbers and exceptions change between editions.
- The cheapest thing on this page
- Debris off the roof, out of the valleys, out of the gutters, away from vent inletsIt is also the only item that has to be repeated. California's draft Zone 0 rule would make it a legal duty in mapped areas: the roof and rain gutters of an occupied structure shall be kept clear of leaves, needles, and other combustible debris.
This page's advice — openings and debris before covering — and where it is wrongSection link
The position taken here is that on most existing houses the covering is not the weakest part of the roof, and that money spent on vents, eave detailing and maintenance buys more than money spent upgrading a covering that is already Class A. There are real situations where that is the wrong call.
Best when
- The existing covering is already part of a Class A assembly and has service life left — asphalt, tile, slate, metal, or a listed composite in sound condition.
- The attic is vented through gable-end vents, or through generic off-ridge vents, or through vents set in open-eave blocking. Those are the three geometries IBHS found least able to keep embers out.
- The house has deep overhangs, an open-eave underside, or complex geometry with valleys that collect needles from an overhanging tree.
- A re-roof is already scheduled, so the details that decide this hazard — the eave underside, the drip edge, the covering voids, the vent products — can all be corrected while the covering is off and the deck is visible.
- The property is in a mapped hazard zone where the jurisdiction has adopted WUI provisions, so the work has to satisfy a listing anyway and the inspection is a free second opinion.
- Nobody has been in the attic in a decade and nobody knows what the vents are.
Think twice if
- The covering is wood shake or wood shingle. Then the covering is the problem, and no amount of vent work compensates. The 2025 IBHS Wildfire Prepared Home Technical Standard does not permit wood shake, wood shingle or any wood roof covering material for its designation, regardless of test rating.
- The roof is at or past the end of its planning range. Detailing work on an assembly that comes off in three years is money spent twice.
- The house sits above a slope of continuous fuel with nothing between it and the vegetation. Defensible space and the first five feet come first; a perfect vent on a house with a woodpile against the wall is a solved problem next to an unsolved one.
- The proposal converts a vented attic to an unvented one as a wildfire measure without anyone doing the moisture design. That trade is legitimate and is sometimes the right answer, but an improvised unvented assembly buys a condensation failure to replace an ember failure.
- The building predates 1990 and the work would disturb old shingles, felts or mastics. Those may contain asbestos, and testing comes before disturbance.
- The money on the table is an insurance mitigation credit rather than the work itself. Credits, eligibility and non-renewal decisions are carrier and state specific, and no page can promise you one.
What changes the answer
- Whether your jurisdiction has adopted WUI construction provisions at all, and whether your parcel is inside a mapped zone.
- Whether the roof is being replaced or only maintained — a re-roof re-opens every detail; maintenance re-opens none of them.
- Eave construction: open eave with exposed rafter tails, boxed soffit, or no overhang at all. The three behave differently and are detailed differently.
- Vent geometry and location, which decide far more than mesh size does.
- Covering profile. A flat covering has almost no voids at the eave; a barrel tile or a ribbed panel has a row of them.
- What is growing over the roof. A tree that drops needles into a valley re-creates the fuel every autumn no matter what is under it.
- Whether the attic contains stored combustibles near a vent. IBHS observed that embers entering an attic dispersed rather than concentrating — but noted that a cardboard box beside a vent would stop them and let them pile up.
- The wind. Ember entry through under-eave vents rose with wind speed in IBHS's tests; entry through ridge and turbine vents fell.
The stack, and the seven openings around itSection link
A roof resists fire as a system of layers with a laboratory pedigree, and it admits fire through the holes that were put in it on purpose. Those are two separate subjects, and most wildfire roofing advice collapses them into one.
Key to the diagram
- The ember shower. Burning fragments lofted by the fire and carried on the wind, landing on and around the building before any flame front is visible.
- The ridge vent. An outlet at the top of the slope, sitting under the covering. Its own vulnerability is usually the debris that collects at its inlet.
- The tested assembly. Roof covering, underlayment and roof deck. The fire class belongs to the three of them together.
- Needles and leaves on the covering. Fine fuel delivered by the same wind that delivers the embers, and it collects in the valleys and behind anything that sticks up.
- The covering void at the eave. The space a profiled covering leaves between itself and the deck at the first course — an opening straight into the assembly.
- The soffit vent. The intake opening in the underside of a boxed eave, and the route into the attic from below.
- Debris in the gutter. A trough of dry fuel held against the fascia and the edge of the deck, at the lowest and most accessible point on the roof.
1 · The class belongs to the stack
A fire class — A, B or C — is the result of a laboratory test, and the thing tested is an assembly. UL Solutions describes its roofing service as fire tests of roof coverings comprising three exposures: spread of flame, intermittent flame, and burning brand, run to UL 790 and ASTM E108. What goes into that apparatus is a built-up specimen: a deck of a stated material and thickness, at a stated slope, with a stated underlayment fastened a stated way, carrying the covering.
This is not a technicality, and you can check it yourself. CAL FIRE’s Office of the State Fire Marshal publishes its Building Materials Listing for wildland-urban interface products, and its roofing category is called, in the state’s own words, “Non-Wood Roof Covering/Assemblies.” A single listing in it — one standing-seam system rated Class A under ASTM E108 — specifies nominal 7/16-inch OSB sheathing with a maximum 1/8-inch gap at all joints fastened with 2-inch nails at 8 inches on centre, a nominal 1/2-inch cover board with its joints staggered from the sheathing, a named synthetic underlayment stapled with a 3-inch overlap, and the panel itself set so its rib lands 6 inches from the OSB joint and fastened with a named screw in the nail strip. That is what “Class A” is a shorthand for.
So the honest reading of a manufacturer’s “Class A” claim is: this covering achieved Class A in the assemblies it was tested in. Substitute the deck, substitute the underlayment, change the slope, change the fastening, lay it over an existing covering that was not in the listing, and you are outside the tested assembly. Whether that matters legally depends on your jurisdiction. Whether it matters physically does not depend on anything.
California’s residential WUI provisions said the quiet part out loud. One California building department’s published checklist for the 2019 California Residential Code reproduced R337.5.1 as: roofs shall have a roofing assembly installed in accordance with its listing and the manufacturer’s installation instructions. The listing is the requirement. The covering is a component of it. That edition has since been superseded — California replaced Chapter 7A and its residential counterpart with Title 24 Part 7 on January 1, 2026 — so read R337 here as an illustration of the mechanism, not as current text.
2 · The ember arrives first, and it arrives alone
The mental picture most people carry — a front of flame sweeping up to a house — is not how most houses are lost. Stephen Quarles, writing for IBHS, opens his vent study with the sentence “wind-blown embers are the principal cause of building ignitions,” and reaches back to the 1961 Bel Air fire, where a report on that fire described not a contiguous fire boundary but “scores of large fires scattered over a wide area, each sending thousands of brands into the air.” He also cites a survey of the houses affected by a January 1944 fire in Victoria, Australia, which found that “practically all the houses ignited inside, i.e., in the roof space, in rooms, or under the floors, due to the ingress of flame, sparks, and embers through openings such as ventilators, eaves, and windows.” NIST’s wildland-urban interface fire group puts the modern version plainly: firebrands are a leading cause of structure ignitions in these fires.
The USDA Forest Service work that underpins defensible space says the same thing from the other direction. Jack Cohen’s crown-fire experiments exposed wall sections at 33, 66 and 98 feet from a forest edge; the 33-foot section ignited in three of seven crown fires, and the sections at 66 and 98 feet showed no ignitions and no significant scorch in any of them. Cohen’s conclusion is the sentence the whole home-hardening field is built on: “even the large flames of high intensity crown fires do not directly ignite homes at distances beyond 200 feet. Given that fires adjacent to a home do not ignite it, firebrands can only ignite a home through contact.”
Read that as a roofing statement and it is unusually actionable. The roof is the largest horizontal surface on the building, the highest one, and the one with holes in it on purpose. Contact is exactly what it offers.
3 · Vent geometry beats vent mesh
IBHS ran attic vents through its wind tunnel with seven ember generators, at three wind-speed records — nominally 16 to 20 mph, 25 to 31 mph, and 45 to 60 mph — counting entering embers on video and weighing what landed on a panel inside. The pattern that came out is a geometric one, not a material one: “vents that provided a vertical face to the wind were more vulnerable to the entry of wind-blown embers.” That is gable-end vents, generic through-roof off-ridge vents, and vents set into the blocking of open-eave construction.
Two consequences are worth holding onto. First, the labels intake and exhaust describe still-air behaviour and stop being true in a wind event: IBHS found that under the elevated wind speeds typical of wildfires, every under-eave and non-turbine off-ridge vent on the windward side became an inlet regardless of its nominal designation. Second, more wind is not uniformly worse. Ember entry through under-eave vents increased with wind speed, but for ridge and turbine vents it decreased — at higher speeds an entering ember was carried straight across the opening and out the other side, while at lower speeds the heavier ones dropped into the attic.
Mesh still matters, and IBHS is direct about it: quarter-inch screening “should not be used to cover any vent,” with 1/8-inch or 1/16-inch preferred, and the finer screen carrying more cleaning-related maintenance because debris accumulates on it. Where a jurisdiction has WUI provisions, the mesh window is often written into them — the 2019 California residential checklist quoted above required openings not less than 1/16 inch and not more than 1/8 inch, in noncombustible, corrosion-resistant material.
Listed products are the other half of the answer. ASTM E2886 is the standard test method for evaluating the ability of exterior vents to resist the entry of embers and direct flame impingement, and it did not exist until 2014 — meaning vents accepted before then were accepted on the draft version of that procedure. All thirteen vents in CAL FIRE’s WUI vent category in the September 2, 2025 handbook carry E2886 as their test protocol. In the IBHS tests, the listed gable vents outperformed their own backing mesh used alone, which is a useful thing to know before paying for one.
4 · The eave is the hardest part of the roof
An eave overhang hangs in outdoor air with nothing heated under it, which is what makes it the cold end of an ice dam. In a wildfire it is a different problem with the same geometry: a horizontal ceiling over an outdoor space, which traps hot gas and buoyant embers rising off whatever is burning below or against the wall. That is why California’s 2019 residential WUI provisions treated the underside of the eave as a protected surface in its own right — requiring the exposed roof deck under an open eave, and the underside of a boxed soffit, to be noncombustible, ignition-resistant, or protected by a tested assembly — and why they started from the position that vents shall not be installed on the underside of eaves and cornices at all. Those provisions were superseded by Title 24 Part 7 on January 1, 2026; what survives the edition change is the reasoning, not the section numbers.
The exceptions to that rule are where the real design work happens. The 2019 checklist lists three: the enforcing agency may accept a special eave or cornice vent that resists the intrusion of flame and burning embers; the attic may be fully sprinklered; or the exterior wall covering and the exposed eave underside may be noncombustible or ignition-resistant with the vent more than 12 feet above the ground or a walking surface. Two of those three are decisions somebody makes about the whole building, not a product you buy.
IBHS’s finding fits neatly against the code’s instinct. Between the two ways of building an under-eave intake — a vent in the blocking between rafters in open-eave construction, or a vent in the soffit of a boxed eave — the soffit vent was the better performer, because its opening lies parallel to the wind flow rather than facing it. IBHS’s recommendation is explicit that soffited construction is the preferred type, and that finer mesh than the quarter-inch it happened to test there should be used.
5 · Voids, valleys and gutters: fuel you installed by accident
A profiled covering — barrel tile, S-tile, a ribbed metal panel, some stone-coated products — does not sit flat on the deck. At the first course it leaves a row of openings between the covering and the deck, which is why the 2019 California residential WUI text had a clause about it: where the roof profile allows a space between the roof covering and the roof decking, the spaces shall be constructed to prevent the intrusion of flames and embers, fire-stopped with approved materials, or covered by a layer of 72-pound mineral-surfaced non-perforated cap sheet over the combustible decking. That is the bird stop, and it is one of the cheapest parts of an expensive roof — and it decides whether an ember lands on a tile or lands on plywood.
Valleys are the other structural fuel trap, and the same 2019 provisions attached a detail to them: where valley flashing is installed it is to be not less than 0.019-inch, No. 26 gauge, corrosion-resistant sheet metal, over not less than one layer of 72-pound mineral-surfaced non-perforated cap sheet, at least 36 inches wide, running the full length of the valley. A valley is where two planes dump water, and also where two planes dump needles.
Then there is the gutter, which is a trough designed to hold things at the exact point where the deck edge, the fascia and the eave underside all meet. The same 2019 residential WUI text required roof gutters to be provided with a means to prevent the accumulation of leaves and debris; the DOE Building America Solution Center recommends gutter screens for the same reason, plus a metal drip edge that extends into the gutter to cover the edge of the flammable roof decking and keep out embers. IBHS adds a warning that applies to plastic ridge vents in particular: the greatest vulnerability of these vents may be ember ignition of vegetative debris accumulating at the inlet, and the flaming exposure to the plastic components that follows.
None of that is glamorous. It is also the part of this page that costs the least and has to be done the most often.
6 · The unvented option, and the bill that comes with it
If vents are the route in, removing them is an obvious move, and it is a legitimate one. The Department of Energy’s Building America Solution Center recommends considering an unvented attic design for wildfire resistance, and notes that soffit vents, roof vents and gable vents can be entry points for wind-blown rain, burning embers and salt-laden air. It is equally clear that this is a choice, not a hierarchy: vented and correctly designed unvented assemblies are both recognised approaches, selected on climate, building design, use of the space and the location of the HVAC equipment.
The caution is that an unvented attic is a moisture design, not a deletion. Getting it wrong moves the failure rather than removing it: the sheathing that no longer sees outdoor air also no longer dries to it, and the assembly has to be built so the sheathing stays warm enough and the interior side is detailed for it. Which insulation, how much of it has to be air-impermeable, and what vapour control the ceiling side needs are set by climate zone and by the code your jurisdiction actually adopted. That is a conversation for a designer and the ventilation guide, not a line item on a roofing proposal.
One real Class A listing, line by lineSection link
This is a single entry from CAL FIRE's Building Materials Listing for wildland-urban interface products — listing 8180-2299:0501, a standing-seam metal system rated Class A under ASTM E108. Nothing here is edited except the layout.
| Layer or condition | What the listing actually says | What it means if the job differs |
|---|---|---|
| Roof deck | Nominal 7/16 in OSB sheathing, maximum 1/8 in gap in all joints, fastened with 2 in nails at 8 in on centre. | A different sheathing thickness, a plank deck, wider joints or a different nailing pattern is a different specimen from the one that was tested. |
| Cover board | Nominal 1/2 in gypsum-based cover board, installed per the manufacturer's instructions, joints staggered from the sheathing, fastened with eight 2 in nails per 4 ft × 8 ft sheet. | Omitting the cover board removes a layer the tested assembly contained. This is the layer most often left out of a like-for-like quote, because it is invisible afterwards. |
| Underlayment | A named synthetic underlayment, stapled to face, with a 3 in overlap. | Substituting felt, or a different synthetic, or changing the lap or the fastening, changes the layer directly under the covering — the one that meets fire first if the covering is breached. |
| Roof covering | A named 16 in wide, 26 gauge standing-seam panel, with the rib or joint placed 6 in from the OSB joint, fastened with #10-12 (1 in) pancake head wood screws in the nail strip. | A lighter gauge, a different panel, a different screw or a different rib placement is a different covering condition from the one in the listing. |
| Slope | 5:12. | Slope is part of the tested condition, not a free variable. A listing that says 5:12 has been tested at 5:12. |
| Test and rating | Test protocol ASTM E108. Rating: Class A. | The rating attaches to the whole row above it. It is not a property carried by the panel on its own. |
Read this table one item at a time
Roof deck
- What the listing actually says
- Nominal 7/16 in OSB sheathing, maximum 1/8 in gap in all joints, fastened with 2 in nails at 8 in on centre.
- What it means if the job differs
- A different sheathing thickness, a plank deck, wider joints or a different nailing pattern is a different specimen from the one that was tested.
Cover board
- What the listing actually says
- Nominal 1/2 in gypsum-based cover board, installed per the manufacturer's instructions, joints staggered from the sheathing, fastened with eight 2 in nails per 4 ft × 8 ft sheet.
- What it means if the job differs
- Omitting the cover board removes a layer the tested assembly contained. This is the layer most often left out of a like-for-like quote, because it is invisible afterwards.
Underlayment
- What the listing actually says
- A named synthetic underlayment, stapled to face, with a 3 in overlap.
- What it means if the job differs
- Substituting felt, or a different synthetic, or changing the lap or the fastening, changes the layer directly under the covering — the one that meets fire first if the covering is breached.
Roof covering
- What the listing actually says
- A named 16 in wide, 26 gauge standing-seam panel, with the rib or joint placed 6 in from the OSB joint, fastened with #10-12 (1 in) pancake head wood screws in the nail strip.
- What it means if the job differs
- A lighter gauge, a different panel, a different screw or a different rib placement is a different covering condition from the one in the listing.
Slope
- What the listing actually says
- 5:12.
- What it means if the job differs
- Slope is part of the tested condition, not a free variable. A listing that says 5:12 has been tested at 5:12.
Test and rating
- What the listing actually says
- Test protocol ASTM E108. Rating: Class A.
- What it means if the job differs
- The rating attaches to the whole row above it. It is not a property carried by the panel on its own.
Product names are omitted here deliberately: this is a worked example of what a listing contains, not a recommendation of any product. The listing itself is public and names them. CAL FIRE states that its approvals rest on technical data submitted by applicants, that products which are not listed may still comply with the prescriptive standards, and that the local authority having jurisdiction has the right to approve or disapprove products for use in its area.
Which vents let embers in, and whySection link
In 2013–2014 IBHS put a 1,200 sq ft test building with 18-inch overhangs into a wind tunnel, ran seven ember generators at it, and counted what got inside. The table below reorganises the study's own relative-performance ratings so the pattern is visible: geometry decides more than mesh does.
| Vent location and type | How the opening meets the wind | IBHS relative performance | What to take from it |
|---|---|---|---|
| Under-eave — vent in open-eave blocking, 1/4 in mesh | Vertical face, perpendicular to the flow | Poor | The worst of the two intake options. Entry rose as wind speed rose. |
| Under-eave — vent in a boxed soffit, 1/4 in mesh | Horizontal, parallel to the flow | Best of the inlet options | IBHS recommends soffited construction as the preferred type — and finer mesh than the 1/4 in it happened to test. |
| Gable end — 1/4 in square mesh | Large vertical face in a wall | Poor | Few vents means large vents. Size and orientation are the problem before mesh is. |
| Gable end — 1/8 in square or 1/8 in diamond mesh | Large vertical face in a wall | Fair | A real improvement over 1/4 in, and still the most exposed location on the roof. |
| Gable end — 1/16 in square mesh | Large vertical face in a wall | Good | Embers that got through were small enough to self-extinguish before reaching the attic floor. Needs more cleaning. |
| Gable end — listed wildfire-resistant vent | Large vertical face, with baffles or an intumescent honeycomb core | Good | Outperformed its own backing mesh used alone. IBHS still advises avoiding gable vents where an alternative exists. |
| Through-roof off-ridge — generic vent, 1/4 in mesh | Vertical face presented to the flow | Poor | Behaved like a small gable vent on the roof plane. |
| Through-roof off-ridge — turbine | Rotating, consistently an outlet | Good | Only while it spins freely. IBHS notes keeping it in working order matters. |
| Through-roof off-ridge — listed vent with steel wool fill | Louvred, with an infill the ember has to pass through | Best | The steel wool infill was effective at minimising entry into the attic space. |
| Ridge — Miami-Dade wind-driven-rain-compliant, external baffles present | Under the covering, baffled, consistently an outlet | Best | The external baffle eliminated ember entry into the attic in these tests. |
| Ridge — the same vent with the external baffle removed | Under the covering, unbaffled | Fair | At high wind an entering ember was carried straight across and out; at low wind the heavier ones dropped into the attic. Low wind is the likelier wildfire condition. |
Read this table one item at a time
Under-eave — vent in open-eave blocking, 1/4 in mesh
- How the opening meets the wind
- Vertical face, perpendicular to the flow
- IBHS relative performance
- Poor
- What to take from it
- The worst of the two intake options. Entry rose as wind speed rose.
Under-eave — vent in a boxed soffit, 1/4 in mesh
- How the opening meets the wind
- Horizontal, parallel to the flow
- IBHS relative performance
- Best of the inlet options
- What to take from it
- IBHS recommends soffited construction as the preferred type — and finer mesh than the 1/4 in it happened to test.
Gable end — 1/4 in square mesh
- How the opening meets the wind
- Large vertical face in a wall
- IBHS relative performance
- Poor
- What to take from it
- Few vents means large vents. Size and orientation are the problem before mesh is.
Gable end — 1/8 in square or 1/8 in diamond mesh
- How the opening meets the wind
- Large vertical face in a wall
- IBHS relative performance
- Fair
- What to take from it
- A real improvement over 1/4 in, and still the most exposed location on the roof.
Gable end — 1/16 in square mesh
- How the opening meets the wind
- Large vertical face in a wall
- IBHS relative performance
- Good
- What to take from it
- Embers that got through were small enough to self-extinguish before reaching the attic floor. Needs more cleaning.
Gable end — listed wildfire-resistant vent
- How the opening meets the wind
- Large vertical face, with baffles or an intumescent honeycomb core
- IBHS relative performance
- Good
- What to take from it
- Outperformed its own backing mesh used alone. IBHS still advises avoiding gable vents where an alternative exists.
Through-roof off-ridge — generic vent, 1/4 in mesh
- How the opening meets the wind
- Vertical face presented to the flow
- IBHS relative performance
- Poor
- What to take from it
- Behaved like a small gable vent on the roof plane.
Through-roof off-ridge — turbine
- How the opening meets the wind
- Rotating, consistently an outlet
- IBHS relative performance
- Good
- What to take from it
- Only while it spins freely. IBHS notes keeping it in working order matters.
Through-roof off-ridge — listed vent with steel wool fill
- How the opening meets the wind
- Louvred, with an infill the ember has to pass through
- IBHS relative performance
- Best
- What to take from it
- The steel wool infill was effective at minimising entry into the attic space.
Ridge — Miami-Dade wind-driven-rain-compliant, external baffles present
- How the opening meets the wind
- Under the covering, baffled, consistently an outlet
- IBHS relative performance
- Best
- What to take from it
- The external baffle eliminated ember entry into the attic in these tests.
Ridge — the same vent with the external baffle removed
- How the opening meets the wind
- Under the covering, unbaffled
- IBHS relative performance
- Fair
- What to take from it
- At high wind an entering ember was carried straight across and out; at low wind the heavier ones dropped into the attic. Low wind is the likelier wildfire condition.
Two cautions the study makes itself. Ratings are a composite of video ember counts, weighed ember deposits and observed strikes on a cotton pad, within one experiment — they are not a product standard, and no vent is named here. And in no test did the cotton transition from smouldering to flaming, which IBHS attributes to embers dispersing on the attic air currents rather than concentrating; it notes that combustibles stored beside a vent would change that by giving the embers somewhere to pile up.
What changes this on a real buildingSection link
- Fire
Every fire classification on this page belongs to a tested assembly. Underlayment and deck conditions can change the classification, which is why the listing names them. A covering advertised as Class A, laid over an underlayment and a deck that were not in its listing, has not been tested in that configuration by anyone.
Class A is also a description of laboratory behaviour under three specific exposures, not a promise about your building. It does not address ember entry through a vent, ignition of debris in a valley, a fire that reaches the deck from underneath through the eave, or radiant exposure from a neighbouring structure. Roofs with legitimate Class A assemblies are lost in wildfires, and those are the routes this page is about — none of which the fire test measures.
Fire classifications apply to tested roof assemblies, not to a covering in isolation. Ask for the listing number, read what it specifies, and compare it to what is on the proposal. Nothing here certifies any assembly for any building.- Code and jurisdiction
There is no nationwide building code for site-built construction in the United States, and there is no nationwide wildland-urban interface code either. What exists is model text — the International Wildland-Urban Interface Code among it — that a state or local government may adopt, amend, delay or decline.
California is the most developed case and it is still moving. CAL FIRE’s Office of the State Fire Marshal states in its September 2, 2025 listing handbook that effective January 1, 2026, Chapter 7A of the California Building Code is replaced by a new Part 7 of Title 24, the 2025 California Wildland-Urban Interface Code. The City of San Diego’s Fire-Rescue Department describes the same change from the receiving end: Part 7 was adopted by the state and effective statewide on January 1, 2026, is based on the 2024 IWUIC, and the city proposed its own local amendments on top — including one requiring that drip edge flashing, where used at the free edges of roofing materials, be noncombustible. That is a roofing requirement that exists in one city and not in the state code above it.
Now compare Oregon. Senate Bill 83, enrolled in the 2025 regular session with an emergency clause taking effect on passage, repealed ORS 477.490 — the statewide wildfire hazard map — along with ORS 455.612 and 455.614. It directs the Department of Consumer and Business Services to adopt the wildfire hazard mitigation standards of section R327 of the 2023 Oregon Residential Specialty Code and to create a process for municipalities to adopt them, applies them only to new construction of new buildings, and says in terms that the department “may not require a local government to adopt code standards.” The State Fire Marshal produces a model defensible-space code and likewise may not require any local government to adopt it.
Two western states with real wildland-urban interface exposure, moving in opposite directions inside nine months: Oregon’s bill passed the Senate in April 2025, and California’s Part 7 took effect on January 1, 2026. That is the answer to “what are the WUI requirements” in the United States: ask your jurisdiction, name the edition, and check the date.
Every code claim on this page records the jurisdiction and the document it came from. None of them is a determination for your address. Record the jurisdiction, the adopted edition, the amendments, the effective date and the official URL, and confirm with the authority having jurisdiction before you rely on anything here.- Wind
Wildfire ember exposure is a wind problem wearing a fire problem’s clothes, and the same wind loads the roof mechanically. IBHS ran its ember tests at records reaching 45 to 60 mph, and the wind that carries embers ahead of the fire is the wind that lifts the first course of shingles.
That interaction is not one this page can resolve for you. Wind performance is site- and building-specific: basic wind speed, exposure category, building height, geometry, pressure zone, enclosure, risk category, attachment and the tested assembly all matter. Whether an assembly can be listed for both a fire class and a wind rating, and whether both survive the substitutions in your proposal, is a question for the listings and the designer.
A marketing mph rating is not a code determination and never has been. Wind design is site-specific and belongs to the authority having jurisdiction and a qualified design professional.- Moisture and ventilation
Reducing vent area for ember resistance changes the drying behaviour of the assembly under it. Finer mesh clogs faster, and a clogged vent is a smaller vent whether or not anybody intended that; IBHS notes explicitly that 1/16-inch screening requires more cleaning-related maintenance than coarser mesh. Ember-resistant products are not automatically area-for-area swaps either, which is why the net free area of the specific listed product is one of the questions below.
Both vented and correctly designed unvented assemblies are legitimate. There is no universal ventilation ratio, and “more ventilation is always better” is not true. What is required, if anything is, is set by the code your jurisdiction adopted, the climate zone and the assembly type.
Do not design to a ventilation number from this or any other website. The net free area required, the conditions on it, and whether it applies to your assembly at all are jurisdiction- and assembly-specific. Confirm with the authority having jurisdiction.- Maintenance
Debris removal is the only item on this page with no capital cost and no end date — which is not the same as free, because the roof and the gutter are both at height and both are somebody’s paid job. California’s draft Zone 0 rule would turn it into an inspected legal duty in the mapped areas: the Board of Forestry and Fire Protection’s April 2026 rule text says the roof and rain gutters of an occupied structure shall be kept clear of leaves, needles, and other combustible debris, and separately that live tree branches be at least five feet above a roof, ten feet from chimneys and stovepipe outlets, and not underneath eaves.
Which is a reasonable maintenance target even where nobody is going to inspect it. The thing to notice is the direction of travel: the rule is not about the roof covering at all. It is about what is lying on it, and what is hanging over it.
Debris clearing is roof and ladder work, and this site does not direct untrained readers onto either. Falls are the leading cause of death for workers in residential construction even with trained crews and fall protection, per OSHA. Hire it out, and never do it while embers are falling, while smoke is in the air, or during a red-flag wind event.- Insurance — the part this page will not guess at
Wildfire exposure sits at the centre of an unstable insurance picture in several states, and roof work is often being done because a carrier asked for it. This site does not model that. Coverage, deductibles, mitigation credits, eligibility, non-renewal, and what a given carrier accepts as evidence of a Class A assembly or a listed vent vary by carrier, by state and by the facts of the policy.
What is worth keeping regardless is the paperwork: the listing numbers for the assembly and the vents, the manufacturer instructions, the permit and inspection records, and dated photographs of the eave, valley and vent details before the covering went on. That file is useful to an underwriter, to an adjuster and to the next owner, and it costs nothing to build while the work is happening.
Nothing on this page is insurance advice and nothing here promises coverage, a credit, a renewal or a claim outcome. Those are decided by your policy language, your carrier and the law of your state.
What is covered, what voids it, and what can actually be repairedSection link
There are three separate documents in play on a wildfire-hardened roof — the fire listing, the manufacturer's product warranty, and the installer's workmanship warranty — and none of them is a promise about fire.
- A covering warranty is not a fire warranty
- Manufacturer warranties on roof coverings are product warranties: they address manufacturing defects and, sometimes, performance over a stated term. Fire loss is an insurance subject, not a warranty subject, and warranty documents routinely exclude it. Read the exclusions in the actual document rather than the headline term.
- The listing is a condition, not a certificate
- California’s 2019 residential WUI text, as published by one California building department, required that roofs have a roofing assembly installed in accordance with its listing and the manufacturer’s installation instructions. That edition has been superseded, but the idea is the durable part. Installing outside the listing can put you outside the classification and outside the warranty at the same time, and the second one is the one your installer will hear about first.
- Vent listings are product-specific
- An ASTM E2886 listing belongs to a specific model, in specific sizes, built as the listing describes — down to the mesh gauge and the core material. It is a manufacturer-and-product document, and it does not transfer to a similar-looking vent, a site-modified one, or one installed differently from its instructions.
- Listing is not the same as compliance
- CAL FIRE states that products which are not listed in its Building Materials Listing may still comply with the prescriptive standards, because listing is not a statutory mandate — and separately that the local authority having jurisdiction has the right to approve or disapprove products for use in its area. Both directions of that are true at once, which is why the AHJ conversation is unavoidable.
Repairability
Partial repairs are where a good assembly quietly stops being the assembly that was tested. Replacing a slope, patching after a satellite dish, or re-flashing a chimney with a different underlayment leaves you with a roof that no single listing describes. That may be entirely acceptable to everyone involved, but it should be a decision rather than an accident — and it is worth writing down what changed, in the same file as the original listing.
Vents are the easy repair and the easy regression. A listed vent damaged in a storm and replaced with whatever the supply house had in stock undoes the most cost-effective part of the whole exercise, and nothing about the roof looks different afterwards.
A warranty is a contract between a reader and whoever wrote it. What it covers, what voids it, whether it transfers, and how it is enforced are set by that document and by the law where the reader lives. Read the actual warranty for the product and the installer in front of you — not a summary of one, including this one.
Questions to ask before you signSection link
These are written to be said out loud. The useful signal is not whether the answer is impressive; it is whether the person can produce a document.
Which listing is this roof assembly, and can I have a copy of the listing itself?
A good answer is a number and a document. A weak answer is a brochure that says Class A. If the assembly is being built to a listing, that listing names the deck, the underlayment, the fastening and the slope, and you can read it against the proposal in ten minutes.
Which layers in your proposal come from that listing, and which are substitutions?
Substitutions are normal and often unavoidable — the existing deck is what it is. The question is whether anyone has noticed. An installer who can tell you which three items differ from the listing is an installer who read it.
Are the vents in this proposal listed to ASTM E2886, and which product and listing number?
E2886 is the standard test method for whether an exterior vent resists ember entry and direct flame impingement. “Fire rated” and “wildfire vent” are marketing phrases; a listing number is checkable.
What is the listed net free area of those vents, and how many does that mean compared with what is up there now?
Ember-resistant vents are not always area-for-area replacements for what they replace, and the balance between intake and exhaust is what makes ventilation work at all. Asking forces the arithmetic to happen before the order goes in rather than after.
What happens at the eave — is it staying open or being boxed in, and what is on the underside?
On this page’s reading it is one of the most consequential details on the roof for wildfire, and it is almost never written into a proposal. Open eave, boxed soffit and no overhang are three different jobs with three different vent answers.
How are you closing the covering voids at the eave, and what is going in the valleys?
For a profiled covering, the answer should involve bird stops, approved fire-stopping, or a cap sheet over the decking. For valleys, it should involve metal of a stated gauge over a stated underlayment, running the full length. Vagueness here is the cheapest failure on the whole roof.
Is my parcel in a mapped hazard zone, which code edition applies, and are you pulling the permit?
Mapped status is a matter of public record and the installer should be able to say. If they cannot name the adopted edition or would rather skip the permit, the inspection you are giving up is a free second set of eyes on exactly the details this page is about.
What will you photograph and hand over before the covering goes down?
Once the covering is on, the deck, the underlayment and the fastening are invisible for the life of the covering. A dated photo set is the only evidence that the assembly matches the listing, and it is the file an underwriter, an adjuster or a buyer will ask for.
Require these in writing
- The listing number and issuing body for the roof assembly, and the test standard behind it.
- Deck material, thickness and condition, plus any re-sheathing or re-nailing included.
- Underlayment product, number of layers, and fastening method and spacing.
- Covering product, profile, and fastener type, length and pattern.
- Every vent by product name, model, listing number and listed net free area, with counts and locations.
- Eave treatment: open or boxed, the material on the underside, and the drip edge material.
- Covering-void treatment at the eave and rakes, named as a product or a method.
- Valley construction: metal gauge, width, and the underlayment beneath it.
- Gutter treatment, including any debris screening, and who owns the cleaning afterwards.
- Permit responsibility, inspection stages, and the jurisdiction and code edition being built to.
- What is explicitly excluded — defensible space, tree work, siding, decks, windows, and crawlspace vents are usually somebody else's scope.
Misconceptions and failure modesSection link
Common misconceptions
Common belief
A Class A roof is a fireproof roof.
What is actually true
Class A is the top of a three-step classification produced by a laboratory test of an assembly. UL Solutions describes that test as three exposures — spread of flame, intermittent flame and burning brand — under UL 790 and ASTM E108. It is a measured resistance under stated conditions, not an immunity, and it says nothing at all about the vents in the roof, the needles in its valleys, or a fire that reaches the deck from under the eave.
Common belief
The shingle is what carries the Class A rating.
What is actually true
The listing carries it. CAL FIRE’s own listing category is called “Non-Wood Roof Covering/Assemblies,” and the individual entries specify the deck material and thickness, the cover board, the underlayment and how it is fastened, the covering, the fasteners, and the slope. A covering achieves Class A in the assemblies it was tested in.
Common belief
Houses burn in wildfires because the fire front reaches them.
What is actually true
Mostly they do not. USDA Forest Service crown-fire experiments found no ignitions and no significant scorch on wall sections at 66 and 98 feet from a forest edge, and Cohen’s conclusion is that flames from even high-intensity crown fires do not directly ignite homes beyond about 200 feet — leaving firebrand contact as the mechanism. IBHS states that wind-blown embers are the principal cause of building ignitions.
Common belief
Quarter-inch hardware cloth over the vents handles it.
What is actually true
IBHS’s recommendation after testing is that quarter-inch screening should not be used to cover any vent, and that 1/8-inch or 1/16-inch is preferred. Where a jurisdiction has adopted WUI provisions the mesh window may be written into them — one California building department’s published checklist for the 2019 residential code required openings not less than 1/16 inch and not more than 1/8 inch. And mesh is the smaller half of the answer: the geometry and location of the vent mattered more in the tests than the screen over it.
Common belief
If I install ember-resistant vents I can stop cleaning the roof.
What is actually true
The debris is the fuel. IBHS specifically warns that the greatest vulnerability of ridge and off-ridge vents may be ember ignition of vegetative debris accumulating at the vent inlet, followed by flame exposure to the plastic components most ridge vents are made of. Finer mesh also collects more, and needs cleaning more often, not less.
Common belief
My state has no wildfire building code, so this is a California problem.
What is actually true
Fire behaviour is physics and code adoption is politics, and they are not correlated. Oregon repealed its statewide wildfire hazard map in 2025 and made its own R327 standards something municipalities may adopt rather than must; the hazard did not change when the map did. The absence of a requirement is information about your permit process, not about your exposure.
Common belief
Sealing the attic up unvented is the safe answer.
What is actually true
It is a legitimate answer, and the Department of Energy recommends considering it for wildfire resistance. It is also a moisture design with its own failure mode. Vented and correctly designed unvented assemblies are both recognised approaches, chosen on climate, building design, use of the space and HVAC location — and an unvented conversion made on a roofing proposal, without that design work, trades one failure for another.
How it actually fails
- Ember entry at a gable-end vent
- A large opening in a vertical wall, facing the wind. IBHS found gable-end vents vulnerable for exactly that reason — they are few, therefore large, and their face is perpendicular to the flow. When the vent is on the windward side, wind, embers and wind-driven rain all enter through it.What you can see: A louvered triangle or rectangle in the gable wall with coarse mesh behind it, visible from the ground. Look for debris caught on the screen and for daylight through it.
- Debris ignition at a ridge or off-ridge vent inlet
- Wind-blown needles and leaves collect at the vent inlet; an ember lands in them; the resulting flame is held against the plastic body of the vent. IBHS names this as the greatest vulnerability of commercially available ridge vents, which it notes are made of plastic materials.What you can see: From the ground with binoculars: a dark line of packed debris along the ridge, or a mat of needles around an off-ridge vent. In the gutter below, the same material in bulk.
- Ignition under an open eave
- Hot gas and buoyant embers from something burning below or against the wall are trapped against a horizontal outdoor ceiling, with exposed rafter tails and exposed deck underside above them. This is why California’s 2019 residential WUI provisions protected the eave underside as a surface in its own right and started from a prohibition on vents there.What you can see: Bare plywood or bare rafter tails visible when you look up under the overhang, and vents set into the underside of it.
- Ember entry through a covering void at the eave
- A profiled covering leaves an open space between itself and the deck at the first course. The 2019 California residential WUI text required those spaces to be fire-stopped or covered by a 72-pound cap sheet over the combustible decking; where nothing was done, the void is a direct path onto the deck.What you can see: On tile or ribbed metal, look along the eave line from the ground: a row of open half-moons or open ribs means no bird stop.
- Fire at the deck edge, started in the gutter
- A gutter full of dry needles sits against the fascia and the edge of the deck. The Building America Solution Center recommends gutter screens and a metal drip edge extending into the gutter specifically to cover the exposed edge of the flammable roof decking.What you can see: Plants growing in the gutter, staining on the fascia, and granules or needle mulch overflowing at the downspout. All of it visible from the ground.
- An assembly that no listing describes
- A Class A covering laid over an underlayment, a deck, an existing covering or a slope that was not in its listing — often during a partial repair years later. The rating was earned by a configuration; this is a different configuration.What you can see: Nothing visible. This one only shows up in the paperwork, which is why the photograph-and-file question is on the list above.
- Wood shakes or shingles
- The covering itself is the fine fuel, presented in a well-ventilated horizontal array. The 2025 IBHS Wildfire Prepared Home Technical Standard rules the material out rather than scoring it down: wood shake, wood shingle or any wood roof covering material is not permitted for the designation regardless of test rating, which IBHS attributes to the service life uncertainties of ignition-resistant treatments and coatings.What you can see: Weathered, split, curling wood coursing, often with moss in the keyways and needles packed between the shakes.
Sources and further readingSection link
Understanding Roofing / Published
Scope and limitations
- It cannot tell you whether your building is in a mapped wildland-urban interface or fire hazard severity zone.
- That is a jurisdictional determination made from official maps, and it changes.
- It cannot tell you which code applies to your address, which edition it is on, how it was amended, or when it took effect.
- Every code statement here is attributed to a named jurisdiction and a named document, and none of them is a determination for anywhere else.
- It does not reproduce the current text of the 2025 California Wildland-Urban Interface Code.
- The roofing, vent and eave provisions quoted here come from one California building department's published checklist for the 2019 California Residential Code and are reproduced to show the mechanism, not the current requirement.
- Section numbers, dimensions and exceptions change between editions.
- It does not publish a cost figure.
- Wildfire hardening is priced by roof geometry, eave construction, vent count, access, and local labour, and no defensible national dataset separates that from general re-roof spending.
- The proposal checklist compares scope instead of dollars.
- It does not rank vent products, and it names none.
- The IBHS results describe categories of vent geometry tested in one facility, not a buying guide, and product listings are manufacturer-and-model specific.
- It cannot tell you what your insurer will do.
- Coverage, credits, eligibility and non-renewal are set by policy language, carrier practice and state law, and this page has had no legal review.
- It cannot estimate the probability that any particular house survives any particular fire.
- Ignition depends on the whole home ignition zone, on wind, on fuel, on suppression and on chance, and no roof detail changes that into a guarantee.
State Fire Marshal Listed Wildland-Urban Interface (WUI) Products Handbook, September 2, 2025 edition
CAL FIRE — Office of the State Fire Marshal, Fire Engineering and Investigations Division, Building Materials Listing Program / September 2, 2025
That the state's listing category for roofs is named 'Non-Wood Roof Covering/Assemblies' and is tested to ASTM E108 or UL 790; the worked Class A listing quoted on this page, including its deck, cover board, underlayment, covering, fastener and slope specifications; that the vent category is tested to ASTM E2886; that effective January 1, 2026 Chapter 7A of the California Building Code is replaced by a new Part 7 of Title 24, the 2025 California Wildland-Urban Interface Code; that products not listed by the programme may still comply with the prescriptive standards because listing is not a statutory mandate; and that the local authority having jurisdiction has the right to approve or disapprove products for use in its area.
A product listing directory for California, published by CAL FIRE. It is not a code text, it does not state the requirements a building must meet, and it lists only products whose manufacturers chose to apply. CAL FIRE states its approvals rest on technical data submitted by applicants and that its engineering staff review test results without making independent claim verification. Individual listings are product-specific.
Vulnerability of Vents to Wind-Blown Embers
Insurance Institute for Business & Home Safety (IBHS) — Stephen L. Quarles, Ph.D. / August 2017
That wind-blown embers are the principal cause of building ignitions; the historical Bel Air 1961 and Beaumaris 1944 accounts quoted; the experimental design, including the three wind-speed records of 16–20, 25–31 and 45–60 mph and the seven ember generators; the finding that vents presenting a vertical face to the wind were more vulnerable; that gable-end, generic off-ridge and open-eave blocking vents performed poorest and soffit vents, baffled Miami-Dade ridge vents and listed steel-wool off-ridge vents performed best; that under wildfire wind speeds nominal inlet and outlet designations stop holding; that ember entry rose with wind speed for under-eave vents and fell for ridge and turbine vents; the recommendation that quarter-inch mesh not be used on any vent, with 1/8-inch or 1/16-inch preferred and finer mesh needing more cleaning; that listed vents outperformed their backing mesh alone; the warning about vegetative debris at the inlet of plastic ridge vents; the observation about combustibles stored beside an attic vent; and that ASTM E2886 is the standard test method for evaluating whether an exterior vent resists ember entry and direct flame impingement, published in 2014.
One laboratory study in one test facility, on a 1,200 sq ft test building with 18-inch overhangs, using wood-chip and dowel embers. Its relative performance ratings are comparative within that experiment, not product ratings and not a purchasing standard. It predates the current editions of the codes discussed on this page and describes California acceptances as they stood when the work was done.
Wildland-Urban Fire — A different approach
Jack D. Cohen, Research Physical Scientist, Missoula Fire Sciences Laboratory, Rocky Mountain Research Station, USDA Forest Service
That the home and its immediate surroundings within 100–200 feet principally determine home ignition potential during severe wildland-urban fires; that wall sections placed at 33, 66 and 98 feet from a forest edge ignited in 3 of 7 crown fires at 33 feet with no ignitions or significant scorch at 66 or 98 feet; and that even the large flames of high-intensity crown fires do not directly ignite homes beyond 200 feet, leaving firebrand contact as the ignition route.
Research synthesis about structure ignition and the home ignition zone. It is not roofing guidance, contains no assembly or vent detail, and does not address code requirements. Its experimental figures come from crown-fire experiments on wall sections, not on whole houses.
Wildland-Urban Interface Fire Group
National Institute of Standards and Technology (NIST)
That firebrands are a leading cause of structure ignitions in wildland-urban interface fires, and that firebrand ignition is a significant contributor to the spread of wildfires into communities.
A programme overview page. It states research direction rather than quantified findings, and carries no statistics on structure loss and no roofing or vent specifications.
Design for Wildfire Resistance
U.S. Department of Energy, Building America Solution Center (PNNL)
The recommendation to cover roof edges with metal drip edge extending into the gutter to cover the edge of the flammable roof decking and keep out embers; to cover gutters with gutter screens to prevent accumulation of leaves and pine needles; to box in eaves or install noncombustible or ignition-resistant flat soffit coverings; to use ember- and flame-resistant vents and screen attic vents with mesh no larger than 1/8 inch while avoiding fiberglass or plastic mesh that could melt; and to consider an unvented attic design.
Best-practice guidance for builders and designers, not adopted law anywhere. Its list of Class A roofing types describes coverings commonly found in Class A assemblies; it is not itself a listing and does not establish that any particular product achieves the class in any particular assembly.
Disaster-Resistant Roof Venting
U.S. Department of Energy, Building America Solution Center (PNNL)
That in wildfire events one of the most common means of homes catching fire is the entry of airborne embers into vented roof assemblies through roof vents; that mesh screening at soffit vent openings should be 1/8 inch (3 mm) or less; that certified ridge or off-ridge vents are preferable to gable vents because gable-end vents can circumvent soffit-to-ridge airflow and admit wind-driven rain and embers; and that for the best resistance to wind-borne rain and embers in new construction an unvented attic should be considered.
Guidance rather than code. Its certification reference is to a wind-driven-rain protocol (Florida Building Code TAS 100(A)), which is not an ember-resistance test; ASTM E2886 is the ember standard and this guide does not name it.
Vented versus Unvented Attic
U.S. Department of Energy, Building America Solution Center (PNNL)
That soffit, roof and gable vents can be entry points for wind-blown rain, burning embers and salt-laden air; that the choice between a vented and an unvented attic is made on climate, desire for living or storage space, building design and configuration, and HVAC location; and that both are recognised approaches with their own advantages rather than one being universally correct.
Guidance, not code. Its code references are to specific IRC and IECC editions and are model provisions, not the law in any particular jurisdiction. It does not design an unvented assembly for any specific climate zone.
Roofing testing and certification services
UL Solutions
That UL 790 / ASTM E108 fire tests of roof coverings comprise spread of flame, intermittent flaming, and burning brand exposures.
A services page from the testing laboratory. It names the test components but does not define the Class A, B and C thresholds, and it is not the standard itself.
Wildland-Urban Interface (WUI) Checklist, updated 12/6/19
City of San Carlos, California — Building Division / December 6, 2019
The 2019 California Residential Code Section R337 provisions reproduced on this page: R337.5.1, that roofs shall have a roofing assembly installed in accordance with its listing and the manufacturer's installation instructions; R337.5.2, on fire-stopping roof-covering voids or covering the decking with a 72-pound mineral-surfaced non-perforated cap sheet complying with ASTM D3909; R337.5.3, on valley flashing of not less than 0.019-inch No. 26 gauge corrosion-resistant metal over a 72-pound cap sheet, at least 36 inches wide, running the full length of the valley; R337.5.4, that roof gutters be provided with a means to prevent accumulation of leaves and debris; R337.6.2, that ventilation openings be noncombustible and corrosion-resistant with dimensions not less than 1/16 inch and not more than 1/8 inch; R337.6.3, that vents shall not be installed on the underside of eaves and cornices, and its three exceptions; and R337.7.4 and R337.7.5, on protecting the exposed underside of open and enclosed roof eaves.
A local building department's plain-language checklist for one past code edition, published for its own applicants. It is evidence of what one California jurisdiction told builders under the 2019 CRC. It is not the current requirement anywhere — California moved these provisions into Title 24 Part 7 effective January 1, 2026 — it is not the code text itself, and it has no force outside San Carlos. Use it to understand the mechanism, then confirm the current adopted text with your own authority having jurisdiction.
Code Change Report — 2025 California Wildland-Urban Interface Code
City of San Diego — Fire-Rescue Department / 2025–2026 adoption cycle
That the 2025 edition of the California Building Standards Code, Title 24, Part 7 was adopted by the State of California and effective statewide on January 1, 2026, and is based on the 2024 International Wildland-Urban Interface Code; and that a local jurisdiction layers its own amendments on top of it — including a proposed new Section 504.2.3 requiring drip edge flashing at the free edges of roofing materials to be noncombustible, and proposed Zone 0 requirements applying to existing structures one year after the ordinance effective date, with roofs and rain gutters kept clear of leaves and needles.
A proposal document for one city's local amendments, published during its own review process. The amendments described were proposed rather than confirmed as adopted at the time of reading, and they bind nobody outside San Diego. It is cited here as evidence that local amendment happens, not as a statement of San Diego's current law.
Zone 0 Draft Regulations for full Board consideration — cover memorandum, August 2026
California Board of Forestry and Fire Protection — Executive Officer, Board Counsel and Staff / August 2026
That Assembly Bill 3074 (2020), Senate Bill 504 (2024), Assembly Bill 1455 (2025) and Executive Order N-18-25 directed the Board to develop defensible-space standards for the first five feet around structures, described as the ember-resistant zone; that the proposed regulations would apply in State Responsibility Areas and Very High Fire Hazard Severity Zones within Local Responsibility Areas, immediately to new construction and phased over five years for existing structures; and that following Board approval the package goes to the Office of Administrative Law for expedited review, with staff expecting the regulations could become effective in September 2026.
A staff memorandum about a proposed rule, not adopted law. At the time of reading the package had not completed Office of Administrative Law review or been filed with the Secretary of State, and its content could change. Check the Board's own current status before relying on any of it.
Summary of Draft Zone 0 Regulation Language and draft rule text, April 2026
California Board of Forestry and Fire Protection / April 2026
The draft rule language quoted on this page: that the roof and rain gutters of an occupied structure shall be kept clear of leaves, needles, and other combustible debris; that tree branches shall be at least ten feet from chimneys and stovepipe outlets, at least five feet above a roof and at least one foot from walls, and shall not be underneath eaves; and that no plants or vegetation are permitted under eaves, within one foot of the structure, or within two feet of windows, doors or vents.
A draft under active revision, superseded by later versions of the same rulemaking. It is not law, it applies only within the California areas the rule would cover, and the quoted language may not survive into the adopted text.
Enrolled Senate Bill 83, 83rd Oregon Legislative Assembly, 2025 Regular Session
Oregon Legislative Assembly / 2025 Regular Session
That Oregon repealed ORS 455.612, 455.614, 476.390, 476.394, 477.027, 477.161 and 477.490 — including the statewide wildfire hazard map; that the Department of Consumer and Business Services shall adopt the wildfire hazard mitigation code standards of section R327 of the 2023 Oregon Residential Specialty Code, create a process for municipalities to adopt them, and may apply them only to new construction of new buildings; that the department may not require a local government to adopt those standards; that the State Fire Marshal shall create a model defensible-space code consistent with and not exceeding sections 603 and 604 of the 2024 International Wildland-Urban Interface Code, and may not require a local government to adopt it; and that the Act declares an emergency and takes effect on its passage.
Oregon law as enrolled. It says nothing about any other state, and it does not describe the content of R327 or of the model defensible-space code the State Fire Marshal was directed to produce. Subsequent sessions and agency rulemaking may have changed the picture; confirm the current statute and rules with Oregon's own agencies.
2025 Wildfire Prepared Home Technical Standard
Wildfire Prepared Home, a programme of the Insurance Institute for Business & Home Safety (IBHS) / 2025
That the programme's base-level roof requirement is a roof covering material with a Class A rating when tested in accordance with ASTM E108 or UL 790, and that it names fiberglass composition asphalt shingles, concrete and clay tiles, metal shingles or sheets, and slate as examples rather than as a closed list; and that the standard states that, given the potential service life uncertainties of ignition-resistant treatments and applied coatings, the use of wood shake, wood shingle, or any wood roof covering material regardless of test rating is not permitted. It also requires roof coverings to be kept clear of vegetative debris and, on barrel tile or corrugated coverings, noncombustible bird stops at the eave ends.
A voluntary designation standard written by an insurer-funded research institute, not a code, a listing or adopted law anywhere. It sets eligibility for one programme's certificate; it does not determine what any jurisdiction permits, and it does not establish that any particular product achieves Class A in any particular assembly.
IBHS research shows creating an ember-resistant buffer around a home cuts its risk of igniting from a wildfire in half
Insurance Institute for Business & Home Safety (IBHS) / August 26, 2025
IBHS's position that a wildfire-resilient home has a Class A fire-rated roof together with ember-resistant vents and a noncombustible zone immediately around the building, and that clearing vegetation from the perimeter materially improves survival odds.
A press release summarising a 2021 study conducted with a commercial analytics firm. Its headline survival figure is not reproduced as a number on this page, because the release does not publish the study's method, sample or confidence interval in a form a reader could check. Treat it as a statement of IBHS's position, not as a measured probability for any building.
Residential fall protection guidance
U.S. Occupational Safety and Health Administration (OSHA)
The safety escalation on this page: that fall exposure in residential roofing work is serious enough that this site does not direct untrained readers onto roofs or ladders, before adding smoke, wind or ember fall to it.
Occupational guidance addressed to employers and workers in residential construction. It is not homeowner guidance, and it says nothing about wildfire.