Decks & stairs

Zone 0 deck requirements in California: the five-foot zone starts at your deck, not your wall

Fact-checked August 19, 2026·Sources at the end of this article

The zone is measured from the deck, not just the house

Five feet from the exterior wall: that is how most homeowners picture Zone 0. The regulation draws the line differently. Here is the definition, verbatim:

Zone 0 is the area within five (5) feet around each Occupied Structure, beginning at the exterior surface of the exterior wall, roof, attached deck, stairs, or pergola and extending five (5) feet out, or to the property line, whichever comes first.

14 CCR §1298.04(a), Board of Forestry July 2026 draft rule text, carried into the August 19, 2026 package the Board approved.

The practical effect: a deck extending twelve feet from your back wall pushes the outer edge of Zone 0 to seventeen feet from that wall. Planting beds, mulch, fence sections and stored items within five feet of the deck edge and stairs all sit inside the zone. New to the concept? Start with what Zone 0 actually is.

The definition of "Occupied Structure" is where the August package made its most consequential change for decks. The July draft read:

An Occupied Structure, for the purpose of determining an ember-resistant zone, includes an attached deck, stairs, or pergola, but does not include patios, decks, stairs, or pergolas made of non-Combustible materials. For the purposes of these regulations, an attached deck, stairs, or pergola includes those that are self-supporting and within one (1) foot of the Occupied Structure.

Board of Forestry July 2026 draft rule text, definitions.

The August 19, 2026 package narrowed that carve-out to patios alone:

An Occupied Structure, for the purpose of determining an ember-resistant zone, includes an attached deck, stairs, or pergola, but does not include patios made of Noncombustible materials.

Board of Forestry, definitions in the August 19, 2026 Zone 0 package the Board approved.

The difference is not cosmetic. Under the July draft, a deck, stairs or pergola built of noncombustible materials did not extend the Zone 0 measurement; the zone stayed at the house. Under the version the Board approved, it does extend it. An attached deck, stairs or pergola counts as part of the structure whatever it is built from, so the zone begins at its edge and the five-foot vegetation-free buffer at (b)(6)(B) wraps around it. Only a patio made of noncombustible materials stays outside the definition, and note the capital letter: the August text uses the defined term "Noncombustible", which points at the ASTM E136 furnace test. If you built an aluminum-framed deck on the understanding that it kept Zone 0 at the wall, that is no longer how the measurement works.

The rest of the definition survives unchanged: a self-supporting deck, stairs or pergola within one foot of the structure still counts as attached. A "floating" deck does not escape by not touching the house.

One caution on all of the provision wording quoted here. The August 19 package published in the Board's binder is the pre-meeting deliberative draft. Amendments made from the floor would not appear in it, and no certified "as adopted" text has been published yet, so treat these as the provisions in the package the Board acted on, with the certified text pending.

Under the deck: what the regulation requires

The under-deck provision is short and unambiguous:

The areas underneath decks, balconies, pergolas, and stairs shall be kept free of vegetation and Combustible items.

14 CCR §1298.04(b)(3), Board of Forestry July 2026 draft rule text, unchanged in the August 19, 2026 package; a corresponding provision appears in the State Responsibility Area text at §1299.03(d).

Separately, the rule states: "No firewood shall be stored in Zone 0" (§1298.04(b)(4)), which covers the classic under-deck woodpile twice over. Where it should go instead: the firewood storage guide.

One reason to do this work regardless of the state timeline: the Safer from Wildfires insurance regulation (10 CCR §2644.9, operative October 14, 2022) requires insurers that price on wildfire risk to credit enumerated mitigation measures, and "Clearing of vegetation and debris from under decks" is one of them. That regulation places its obligations on insurers rather than homeowners, and it is already in force.

New construction must comply on the effective date. No calendar dates exist yet because no effective date exists. The timeline and enforcement guide tracks the phases.

The five-foot vegetation buffer around attached decks and stairs

The regulation does not ban all plants from Zone 0, but it creates vegetation-free buffers in specific places, and the largest one wraps around the deck:

There shall be a minimum five (5) feet of vegetation-free buffer spanning out from the edge of any attached deck, stairs, or pergola.

14 CCR §1298.04(b)(6)(B), Board of Forestry July 2026 draft rule text, unchanged in the August 19, 2026 package.

The full buffer set under §1298.04(b)(6): no vegetation under eaves, within one foot of the structure where there is no eave, within five feet of an attached deck, stairs or pergola, or within two feet of windows, doors, posts or vents. The deck buffer is the deepest of the four, at five times the base-of-wall distance. Shrubs planted along a deck skirt are exactly what it targets. Because the August package counts noncombustible attached decks as part of the structure, this buffer reaches around a metal or concrete deck as well, which is new. Outside the buffers, the rule still permits well-maintained low plants, including lawns; see the plants and vegetation guide. For existing homes, the buffers fall in the rule's later phase: three years from the effective date, or up to five on a local fire agency's timeline.

What the regulation does not say about deck boards

Here is the part the scare copy skips. Neither the July 2026 draft nor the August package the Board approved contains a provision requiring replacement of combustible deck boards or retrofit of existing deck materials. The deck provisions are limited to how the zone is measured, the vegetation buffers, and keeping the areas underneath clear. Your existing redwood deck is not banned by this rule.

Two more honest gaps. The rule has no provision expressly regulating furniture on top of deck surfaces, unlike San Diego's guidelines and the IBHS standard, which both address it. And the Board's summary offers exactly one piece of deck-hardening advice, labeled optional:

While not required, it is best practice to install metal screening around the deck base to keep embers and debris out.

Board of Forestry July 2026 draft summary, Figure 6 caption.

San Diego: deck rules already in force

The City of San Diego's Zone 0 rules (SDMC §512.0604) apply to all structures in a Very High Fire Hazard Severity Zone within city limits. They have been in force for new structures since February 28, 2026, apply to existing structures beginning February 28, 2027, and carry a full-compliance target of February 28, 2029. San Diego measures the zone from the same starting points the state rule uses: the exterior wall surface, attached deck, stairs or pergola, extending five feet or to the property line, whichever comes first. And its guidelines are explicit that the deck itself stays:

Attached combustible decks and other structures, such as balconies and stairs, do not require replacement because they are considered part of the existing structure. Zone 0 only applies to combustible materials located on or beneath attached horizontal surfaces of decks, balconies, and stairs.

City of San Diego, Zone 0 Guidelines for Existing Structures (Rev. 4/22/2026), Section 4.7.

What San Diego requires on and under the deck goes further than the state rule. On deck surfaces, "items such as firewood, combustible storage, combustible planters, or combustible outdoor furniture are prohibited" within five feet of exterior walls, and potted plants must sit at least five feet from those walls. Underneath, the area must stay free of combustible storage and vegetative debris, and "an 1/8" non-combustible mesh is required to prevent the accumulation of debris for decks 4 feet or less in height." Relocating under-deck storage is a Year 1 maintenance action beginning February 28, 2027. The city's voluntary home-hardening attachment also suggests noncombustible or OSFM-approved WUI products when you replace deck boards anyway; that is a suggestion, not a requirement. Full coverage in our San Diego Zone 0 guide.

Berkeley's EMBER rules (effective January 1, 2026 in the Grizzly Peak and Panoramic mitigation areas) likewise require all areas within five horizontal feet of any structure, outbuildings, attached deck or stairs (including under attached decks and stairs) kept free of combustible material. Not sure whose rules cover your parcel? Start with does Zone 0 apply to my home.

IBHS: the voluntary standard goes further

The IBHS Wildfire Prepared Home standard (2025) is voluntary; it matters if you want the certification some insurers credit. And it treats decks more aggressively than the state rule or San Diego. It measures its 0–5 foot noncombustible zone from the outermost posts of a deck or overhead structure, and the zone "extends vertically to the sky."

Underneath an elevated deck, the standard requires removing all vegetation and combustible groundcover to bare mineral soil (noncombustible hardscape such as gravel and pavers is permitted) and six inches of vertical noncombustible material at the base of posts, supporting walls and stairs. It also states, flatly: "Shall have nothing stored underneath." Decks with a walking surface four feet or less above the ground must be fully enclosed with noncombustible, corrosion-resistant mesh, openings no larger than 1/8 inch, from walking surface to ground.

On the walking surface, base-level certification requires noncombustible-framed furniture (cast iron, aluminum, metal), with an exception for small combustible items like chair cushions that can be moved indoors on Red Flag Warning days. Deck boards are regulated only at the higher "Plus" tier: retrofits there need solid noncombustible walking surfaces with no gaps and noncombustible railings within five feet of the home. Base-level certification does not require replacing combustible deck boards. More in our IBHS Wildfire Prepared Home guide.

What this means for you

The deck zone is mostly a labor problem rather than a purchase problem. Nothing on this list is due today, because the state rule has no effective date yet, but the content of the requirements is now settled. In rough order of payoff:

• Measure from the deck edge, not the wall. Walk five feet out from the outer edge of the deck and stairs. That is your working Zone 0 boundary under the adopted state rule and under San Diego's in-force rules. Since the August package, it holds even if the deck is metal or concrete.
• Clear underneath completely. No stored items, no firewood, no leaves or needles, no vegetation. It costs nothing, and under-deck clearing is already a named measure on the insurer mitigation form (10 CCR §2644.9).
• Move the woodpile out of the whole zone. The rule bans firewood anywhere in Zone 0, not just under the deck.
• Audit plantings against the buffer. Anything growing within five feet of an attached deck, stairs or pergola has to go once the rule takes effect, three to five years out for existing homes. If you are replanting this fall anyway, plant outside the line.
• Consider mesh skirting on low decks. Best practice per the Board's summary, required in San Diego for decks four feet or less in height, and required for IBHS certification.
• Do not buy new deck boards for compliance. Nothing in the statewide rule requires it, and San Diego expressly says attached combustible decks do not require replacement.

Work these items alongside the rest of the zone (mulch, fencing, storage) using the full Zone 0 checklist. And if a fence or gate meets the house near the deck, that is its own set of rules: see the California Zone 0 fencing guide.