Zone Zero Decks & Patios Requirements

Phase 2 of California's Zone Zero regulations requires replacing combustible decking surfaces within 5 feet of any structure with non-combustible materials. Decks and patios are significant ember accumulation and ignition points during wildfires.

Non-combustible decking required

Combustible decking within 5 feet of any structure must be replaced. Compliant materials include concrete, pavers, stone, porcelain tile, metal decking, and Class A rated hardwoods such as KAYU Batu and KAYU Golden Bangkirai.

Under-deck space must be enclosed

Open space beneath elevated decks is a prime ember accumulation zone. The April 2026 draft requires the under-deck area to be enclosed with ignition-resistant materials or kept completely clear of all combustible material.

Phase 2, within 5 years of adoption

Deck and patio replacement is a Phase 2 requirement. Your local AHJ sets the specific deadline, up to 5 years from adoption. High-risk counties are expected to set earlier deadlines. Getting quotes now avoids the compliance rush.

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What Zone Zero requires for decks and patios

Wood decks and patios within Zone Zero present two distinct fire risks: the decking surface itself can ignite from embers, and the enclosed space beneath elevated decks accumulates debris that can burn for extended periods and ignite the structure from below.

The April 2026 Board of Forestry draft requires the decking surface within Zone Zero to be non-combustible. For ground-level patios and decks, this means replacing wood, composite, or PVC decking with concrete, pavers, stone, porcelain tile, metal, or Class A rated hardwoods. The 5-foot measurement is from the structure — not from the edge of the deck.

For elevated decks, the space beneath the deck is equally important. Embers can travel under a deck and ignite accumulated debris, dry leaves, or stored items. The under-deck area must either be fully enclosed with ignition-resistant material like fiber cement, metal, or concrete, or kept completely clear of all combustible materials at all times.

Attached stairs and railings within Zone Zero are also covered. Wood or composite railings and stair stringers within 5 feet of the structure should be replaced with non-combustible alternatives. Aluminum, steel, or cable railings are all compliant options. Concrete or metal stair stringers satisfy the structural requirement.

Decks and Patios: Frequently Asked Questions

Common questions about Zone Zero deck and patio compliance, answered clearly.

Does my whole deck need to be replaced or just the part within 5 feet?

Only the portion of the deck within 5 feet of the structure must be non-combustible under Zone Zero. However, if your entire deck is within 5 feet of the structure — which is common for attached decks — the full deck surface must be replaced. The measurement runs from the structure outward, not from the deck edge.

Are composite decking products like Trex compliant with Zone Zero?

Most standard composite decking products including Trex are combustible and do not comply with Zone Zero. Some composite products have Class A fire ratings — check the OSFM Building Materials Listing for California-approved products. Look specifically for WUI-rated composite decking if you prefer a wood-look alternative to concrete or pavers.

Can I keep my wood deck if I store nothing underneath?

No — the decking surface itself is the compliance issue, not just what's stored beneath. A wood deck surface is combustible regardless of what's underneath it. Phase 2 requires replacing the decking material with a non-combustible alternative. Keeping the under-deck area clear is an additional requirement, not a substitute for surface replacement.

What are the most cost-effective compliant decking materials?

Concrete pavers are typically the most cost-effective option for ground-level patios. For elevated decks, aluminum decking and porcelain tile over concrete board offer good value. KAYU Batu hardwood is a premium option with a Class A OSFM rating that maintains a natural wood appearance. Verify local AHJ acceptance before specifying.

What about outdoor furniture and items stored on the deck?

Combustible patio furniture, cushions, rugs, and stored items within Zone Zero should be moved inside or to a non-combustible storage area during Red Flag Warning conditions. The April 2026 draft specifically mentions petroleum-based trash containers and patio cushions as items that should be moved indoors during Red Flag days.

When is the Phase 2 deadline for deck replacement?

Your local AHJ sets the Phase 2 deadline, up to 5 years from final rule adoption. With adoption expected late 2026, the outer deadline would be approximately 2031. However, high-risk counties like Los Angeles are expected to set earlier timelines. Getting an assessment and quote now positions you ahead of contractor demand when deadlines approach.

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Phase 2: Decks and Patios

Get ahead of the Phase 2 deck replacement deadline

Deck replacement is a significant project. Contractors in high-risk areas will be in high demand as Phase 2 deadlines approach. A licensed local contractor can assess your deck, recommend compliant materials for your budget, and provide a quote before the rush begins.

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