New construction in a fire zone is the single best opportunity you will ever have to build a hardened home. Every material and detail is a choice made on paper before anyone swings a hammer. The marginal cost of specifying a Class A roof, listed vents, and noncombustible Zone 0 during design is a fraction of the cost of retrofitting those same items into an existing house a decade later.

That opportunity is also easy to squander. Most builders, including good ones, default to the path of least resistance — whatever the local code requires, whatever their standard framing package delivers, whatever the suppliers have in stock. In California WUI areas, "code minimum" means Chapter 7A, which is a real improvement over older codes but is still a floor, not a ceiling. Outside California, code minimums vary widely and are often below Chapter 7A in practice.

This article is a guide to what a homeowner should insist be written into the specifications for a new home in a fire zone — beyond code minimum, but stopping well short of speculative or experimental systems. If you haven't yet, it's worth reading what home hardening is and why it matters first, because the specifications here all flow from the underlying fire-physics story.

The standards worth specifying to

Before we get into individual components, the three reference standards every spec should name explicitly:

  • California Building Code, Chapter 7A (Materials and Construction Methods for Exterior Wildfire Exposure). The California baseline. Even if you are building outside California, specifying Chapter 7A materials is a useful shortcut because suppliers know the requirements and listed products are widely available.
  • IBHS Wildfire Prepared Home and Wildfire Prepared Home Plus. The IBHS standard goes beyond Chapter 7A in several areas — Zone 0, gutters, deck, and interaction details. Specifying to the Wildfire Prepared Home Plus level is the closest thing to a performance target for a seriously hardened new home.
  • ASTM E2886 / E2886M. The test standard for ember-and-flame-resistant vents. Specify this by number; it is the cleanest way to separate genuine ember-resistant products from vents with marketing claims.

On plans, these are typically called out either in the general notes ("All exterior materials shall comply with CBC Chapter 7A and IBHS Wildfire Prepared Home Plus") or in a dedicated Wildfire Hardening section. Either way, naming them on paper matters — it binds the contractor and the plan checker to the same language.

Roof: Class A assembly, no exceptions

Specify: Class A roof covering and assembly per UL 790 / ASTM E108. No Class B or Class C coverings, and no Class A coverings installed over combustible decking that voids the assembly rating.

Acceptable materials in 2026 for most WUI new construction:

  • Asphalt composition shingles rated Class A (most modern architectural shingles meet this).
  • Standing-seam or concealed-fastener metal roofing over an approved underlayment.
  • Concrete or clay tile with fire-blocking at hips, ridges, and eaves, and bird-stops at the tile ends.
  • Synthetic slate or shake products specifically listed as Class A (many are).

Do not specify:

  • Wood shake or wood shingles. Prohibited in California WUI new construction regardless; inappropriate everywhere else.
  • Roofing "treated" to meet Class A without a factory listing. The listing is what matters.

For more detail on what the rating actually tests, see Class A roofing explained.

On plans, the roofing note should read something like: "Roof covering and assembly: Class A per ASTM E108/UL 790. Underlayment: ASTM D226 Type II or ASTM D4869 Type IV minimum, or as required by manufacturer's listed assembly. Valleys and flashings: noncombustible, min. 26-gauge steel or equivalent."

Vents: listed to ASTM E2886

Specify: All exterior vents (attic, soffit, eave, foundation, dryer discharge screen) shall be listed as flame-and-ember-resistant to ASTM E2886. Product data sheets to be submitted for approval.

This is the specification most likely to be downgraded during value engineering, because code-minimum 1/8-inch mesh is cheap and meets Chapter 7A's prescriptive path. A listed vent is a meaningfully better product and only a modest cost increase on a new build.

Acceptable products are manufactured by Vulcan Vents, Brandguard, O'Hagin, and several others. Do not specify by brand — specify by test standard and let the contractor select from any listed option.

See our explainer on ember-resistant vents for the testing story behind this standard.

Exterior walls: ignition-resistant or noncombustible

Specify: Exterior wall covering shall be noncombustible or ignition-resistant per CBC Chapter 7A, Section 707A.3. Acceptable materials: stucco (three-coat or listed one-coat system), fiber cement lap or panel siding (e.g., Class A rated), brick, stone veneer on noncombustible substrate, metal panel siding with appropriate backing.

A few notes:

  • Stucco is the best all-around performer and is standard on much Western new construction. Three-coat stucco over 2x framing with sheathing is a very hard assembly to ignite in an ember exposure.
  • Fiber cement is the most common alternative and fully Chapter 7A compliant. Specify the manufacturer's WUI-appropriate trim and fastening details, not just the siding itself.
  • Wood siding, even "fire-treated," is not a serious choice for new construction in a WUI area. The treatment wears and no post-fire data supports it as a substitute for noncombustible assemblies.
  • Vinyl siding is prohibited by Chapter 7A and performs badly in radiant heat anywhere.

Eaves and soffits: enclosed, noncombustible

Specify: All eaves shall be fully enclosed with noncombustible soffit material. No open-eave rafter-tail construction in WUI areas. Fascia and trim at eaves: noncombustible or ignition-resistant.

Open eaves — where you can see the rafter tails and the underside of the roof sheathing from outside — are one of the most consistent attic-ignition pathways in post-fire surveys. Enclosing them during new construction is trivial. Retrofitting enclosure into an existing house is not trivial, which is why getting this right the first time matters.

Windows and glazing: dual-pane, one tempered

Specify: All exterior glazing shall be dual-pane insulated glass units with a minimum of one tempered pane, per CBC Chapter 7A, Section 708A. Frames shall be metal, metal-clad, fiberglass, or vinyl with noncombustible trim at the head and sill.

The tempered pane should be the exterior pane where possible; it survives thermal shock better. On elevations facing the worst fuel exposure (canyon, open grassland, neighbor at close spacing), consider both panes tempered.

Skylights: specify Class A-rated skylight assemblies with tempered or laminated glazing. Plastic bubble skylights in fire zones are a poor choice.

Decks: noncombustible or well-separated

Specify: Attached decks shall be constructed with noncombustible framing and decking, or ignition-resistant decking rated for Chapter 7A, over noncombustible framing where practical. Under-deck area shall be either enclosed with noncombustible skirting or maintained with 5 feet of noncombustible clearance to any combustible material.

The IBHS Wildfire Prepared Home Plus standard goes further and requires noncombustible decks (aluminum framing, concrete pavers, or equivalent) with full under-deck clearance. For new construction in a fire zone, this is the right target, even if Chapter 7A permits ignition-resistant wood composites.

If a noncombustible deck is not in budget, the single most important detail is eliminating the gap between deck and siding: the deck ledger and the wall assembly should not form a pocket where embers can lodge and ignite the wall.

Zone 0: designed into the site plan

Specify: The first 5 feet from any exterior wall, deck, or attached structure shall be free of combustible mulch, vegetation, wood fencing, and stored combustibles. Landscape plans shall designate Zone 0 as noncombustible (gravel, decomposed granite, hardscape, or bare soil).

This is a design decision, not a construction decision, and it needs to be on the landscape plan before it is on the site. Combustible foundation plantings that get installed during landscaping are very hard to remove later without a fight with the homeowner's sense of the house's curb appeal — so designing the curb appeal around noncombustible Zone 0 from the beginning matters.

For more on the zones, see defensible space Zones 0, 1, and 2 explained.

Fencing and gates

Specify: The last 5–10 feet of any fence that attaches to the structure shall be noncombustible (metal, masonry, or listed noncombustible composite). No wood fence shall terminate directly against the exterior wall.

This is cheap to design in, awkward to retrofit.

Gutters, downspouts, flashing

Specify: Gutters and downspouts shall be metal (aluminum or steel), not vinyl. Gutters shall be fitted with noncombustible gutter guards (metal mesh or metal diamond pattern). Roof-to-wall flashings and kick-out flashings at all rake-eave intersections.

Interior penetrations and garage

A few details often missed in plans:

  • Garage-to-house penetrations should be sealed per code; a garage fire or a fire entering the garage through the door is a common path into the house.
  • Dryer vents should be terminated with listed ember-resistant backdraft hoods.
  • HVAC intakes in WUI zones should be specified with ember-resistant screening.
  • Door seals — weatherstripping on exterior doors should be continuous; gaps at the threshold under the door are an ember-entry path.

Certification: aim for Wildfire Prepared Home Plus

For a new build, the cleanest performance target is IBHS Wildfire Prepared Home Plus certification. The incremental cost over Chapter 7A is usually modest for new construction — single-digit percentages of the total build cost on most projects — and the certification:

  • Provides an independent third-party verification of the specs and detailing.
  • Is increasingly recognized by insurers for policy availability and discounts.
  • Gives the homeowner a defensible record of the hardening investment at sale.
  • Forces the contractor to actually build to the spec, because certification requires inspection.

Specify Wildfire Prepared Home Plus certification as a project deliverable in the construction contract. Make the certification inspection a condition of final payment. This is one of the cleanest ways to ensure what you specified is what actually got built.

What not to specify

A short list of things sometimes proposed in WUI specs that are not worth your money:

  • Exterior "fire-retardant paint" as a structure solution. Not a substitute for noncombustible siding.
  • "Fireproof" landscaping fabric under mulch. The fabric is fine; the mulch on top is still combustible.
  • Structure-perimeter exterior sprinklers marketed as primary defense. There are legitimate, well-engineered exterior sprinkler systems, but they are a supplement to a hardened structure, not a replacement for one. Specifying a perimeter sprinkler system on a combustible house is doing the expensive thing in the wrong order.
  • "Fireproof vents" that don't carry a listing. If the product doesn't list ASTM E2886, it isn't the spec you want.

Insurance and resale considerations

Two final points that matter enough to put in a section of their own:

Insurance. Underwriters in WUI-heavy states are increasingly specific about what hardening they recognize. A house built to Chapter 7A with a Wildfire Prepared Home Plus certificate is meaningfully easier to insure in 2026 than a house built to generic residential code. Ask your insurance agent — before finalizing specs — which specific items qualify for available discounts. In California, the Department of Insurance publishes the Safer from Wildfires framework that most carriers follow.

Resale. A certified hardened home in a WUI area commands a premium at sale in most current Western markets. The certificate travels with the house. Specs on paper do not; if you can't prove what was built, future buyers won't give you credit for it.

The bottom line

New construction in a fire zone is a rare chance to get hardening right from first principles. The cost difference between a Chapter 7A-compliant spec and a Wildfire Prepared Home Plus spec is small. The cost difference between either of those and a conventional "build to code minimum" house in a non-WUI market is larger, but most of the delta is the regional baseline, not the hardening upgrades.

Write the standards into the general notes. Specify products by test standard rather than brand. Make certification a contractual deliverable. Don't let value engineering remove the listed vents or downgrade the roof assembly. And build Zone 0 into the landscape plan, because no amount of wall-and-roof hardening saves a house surrounded by combustible shrubs.

Get those things right on paper, and the house that comes out the other end of construction will be meaningfully safer than almost anything around it — and will remain so for decades, without the cost and hassle of retrofitting items that should have been specified from the beginning.

This article is informational and not a substitute for licensed professional advice. Cost ranges are general estimates and vary widely by region, house specifics, and market conditions. Before committing to retrofit or new-construction work, consult a licensed contractor with WUI experience, your local building department, and your insurer.