Evergreen Deck Replacement Under Jeffco's WRC

A deck is where many Evergreen houses meet the forest. Ponderosa needles collect between boards, firewood gets stacked underneath, and on a steep lot the open space below the joists funnels wind and embers right at the house. That's why Jefferson County's Wildfire Resiliency Code (WRC), effective July 1, 2026, pays specific attention to decks, and why a deck replacement in Evergreen is a different project than the same job in Lakewood or Littleton.

When the WRC applies to your deck

The county says the WRC isn't retroactive. It applies to new buildings and to the exterior alteration of existing buildings, such as building additions, deck replacements, re-siding and re-roofing, but only on unincorporated properties inside the Jefferson County wildland-urban interface (WUI). Evergreen is unincorporated, and much of it is in the WUI. Check the county's WUI overlay map: Class 1 areas appear in blue, and Class 2 areas, the wildland-urban intermix with moderate to high fire hazard, appear in orange and carry additional hardening and defensible space rules.

The code applies only to what you're working on. The county's own example: a property owner replacing a roof meets the roofing requirements but doesn't have to replace siding, windows or decking. The same logic runs the other way. Replacing the deck brings the deck under the WRC, not the whole house.

What gets hardened

The WRC's structure hardening list includes deck surfaces and framing and underfloor enclosures, along with roofing, gutters, vents, siding, flashing, glazed windows and doors, eaves and soffits. In practical terms, expect your designer and the county reviewer to focus on:

• The walking surface. Decking material that meets the code's fire-performance requirements, rather than standard untreated softwood boards.
• The framing. Joists, beams and posts that meet the code's framing provisions, which can affect lumber choice or call for protection.
• The space underneath. On a steep Evergreen lot, the underside of a deck can be tall and open. The code addresses underfloor areas, so plan whether the underside will be enclosed with approved materials or kept clear.
• Where the deck meets the house. The siding, flashing and doors next to the deck may already be covered by other WRC sections if they're part of the work.

The county points to WRC Chapter 4 for the full regulatory language. Have your builder show you which product and assembly they're relying on for each item.

The deck counts as a structure

For defensible space, Jefferson County measures zones from the structure, and its guidance notes that decks are considered structures as well. Zone 1 runs 0 to 5 feet from a structure, and in both Class 1 and Class 2 areas the county's Zone 1 standards include no plants except mature trees, no combustible mulch such as wood mulch, no storage of firewood or other combustible materials, and no new trees. Mature trees 10 inches in diameter or larger must be pruned so there are no low-hanging branches.

So the 5-foot zone starts at the outer edge of the deck, not at the house wall. A bigger deck pushes the zone farther into your yard. That can mean moving the woodpile, the planters and the mulched beds that often sit right under or beside a mountain deck.

Defensible space is assessed by a county-approved Wildfire Mitigation Specialist whom the property owner hires; see the county page for which permits require it.

Planning an Evergreen deck replacement

1. Check the WUI map for your parcel and class.
2. Measure Zone 1 from the outer edge of the proposed deck, and plan what has to move.
3. Design with the hardening list in hand: decking, framing and underfloor treatment.
4. Engineer for the mountains. Foothill snow and wind loads, plus steep-slope footings, often call for an engineer.
5. Apply through Jefferson County's online permit process, and schedule inspections.

Hire a builder who has already worked under the county's WRC. Any lighting or outlets on the deck need a Colorado-licensed electrician you can verify on DORA's lookup. For general deck costs and materials, see our deck guide, and for Evergreen's wells, septic and steep lots, see the Evergreen area page.