Deck Building in Commerce City, CO

Deck building in Commerce City is one of the few trades on this list with a dedicated city design guide. The Typical Deck Details handout, based on the 2021 IRC, spells out framing, footing, guard, and stair requirements for a single-level residential deck, and the city states that construction cannot deviate from those details without prior approval. Our crew treats that guide as the baseline for every Commerce City deck.

Decks Need a Permit, Filed as a Residential Addition

Commerce City’s permit list requires a permit for porches and decks, including alterations to existing structures. Decks use the Residential Addition permit type, the same category the city uses for room additions, garages, patio covers, and sunrooms. Location on the lot has to respect the same zoning setbacks that apply to the property’s zone district, so a deck cannot simply be sized to fill the available yard without a setback check first.

We confirm the applicable setback table for the specific address before finalizing a deck footprint, since setback figures differ by zone district and lot type across the city’s current Land Development Code.

Guards Are Triggered at 30 Inches of Height

The city’s deck guide states the rule directly: a guard is required when a deck is greater than 30 inches above grade at a point 36 inches from the edge of the deck. That is a measured trigger, not a design preference, and it has to be checked around the full perimeter of the deck because grade often varies from one side of a yard to another.

The same 30-inch-at-36-inch rule applies separately to stairs: stair guards are required when the total rise of the stair exceeds 30 inches at a point 36 inches from the edge of the stair. On a deck with any meaningful height, that means both the platform and the stair run need their own guard evaluation.

Stair Geometry Is Spelled Out to the Fraction of an Inch

The guide sets a minimum stairway width of 36 inches, with stringers built as sawn or solid 2x12s spaced no more than 18 inches on center. Tread and riser dimensions cannot deviate by more than ⅜ inch from one step to the next, and the guide’s own stair diagram calls for a maximum riser height and a minimum tread depth that keep the stair consistent and safe to climb in low light. A stairway with more than 12 feet of total vertical rise needs an intermediate landing, built as its own free-standing deck rather than a simple platform.

Stringers have to bear on footings sized for that load, and the guide is specific about where cut stringers versus solid stringers are allowed to span, so we select stringer type based on the actual rise and run of the stair rather than defaulting to one method for every project.

Footings Go to Frost Depth, and Ledger Attachment Has Prohibited Conditions

Footings are sized from the guide’s tables based on post spacing and beam span, with post bases centered on the footing and requiring a minimum base size. Footing depth in the guide’s diagram is measured down to the local frost depth, which keeps the footing below the level where seasonal freeze-thaw could heave the post. Because footing dimensions vary by the specific beam span and post spacing on a given deck, we size each footing from the guide’s table for that project rather than reusing a number from a different deck.

Ledger board attachment to the house has its own detailed requirements, including a rule that attachment through brick veneer is prohibited. The guide also identifies specific ledger conditions as outright prohibited; where one of those conditions exists, the answer is a free-standing deck or an engineered design rather than a ledger-attached deck built to the prescriptive tables.

We photograph the ledger location and the house’s wall assembly before drilling a single hole, because a masonry veneer, a stucco finish, or an unusual floor framing detail can all change which attachment path the guide actually allows for that house.

How We Sequence a Commerce City Deck

We start with a setback check against the property’s zone district, then lay out the deck footprint, ledger location if applicable, and stair run before ordering material. Footing holes are dug to the frost depth called for in the city’s guide, with size and post spacing confirmed against the guide’s tables for the specific beam span.

Framing follows the guide’s joist and beam tables, with guard posts and blocking planned into the frame rather than added after decking is installed. Once height is confirmed above the 30-inch guard trigger anywhere around the perimeter, guard construction and stair guards are built to the same detail sheet, and any condition that falls outside the guide’s single-level, prescriptive scope is sent to engineering rather than improvised in the field.

Common Questions

Does a new deck in Commerce City need a permit?
Yes. The city’s permit list requires a permit for porches and decks, including alterations to an existing deck. Decks are filed under the Residential Addition permit type.

When does my deck need a guard rail?
A guard is required when the deck is more than 30 inches above grade at a point 36 inches from the edge of the deck. The same 30-inch, 36-inch measurement separately triggers stair guards on the stair run.

How deep do deck footings need to go?
The city’s Typical Deck Details guide requires footings to reach the local frost depth, sized from the guide’s tables based on post spacing and beam span, so the exact depth and diameter depend on the specific deck design.

Can every deck attach to the house with a ledger board?
No. The guide prohibits ledger attachment through brick veneer and lists other prohibited ledger conditions. Where one of those applies, the deck needs to be free-standing or engineered instead of ledger-attached.

Talk to Us About Your Project

Tell us the deck’s approximate size, height above grade, whether it will attach to the house or stand free, and any stairs or landings you need. We will lay it out against the city’s zoning setbacks and the Typical Deck Details guide before footings go in the ground.