Do you need a permit to build a deck in Fort Collins?

When a deck needs a permit in Fort Collins

The City of Fort Collins puts its deck rules in one document, the Residential Deck Guide from Building Services, revised June 24, 2026. It says a permit is required for any of these:

• A deck or porch landing that serves the front door.
• A deck more than 30 inches above grade at any point.
• A deck attached to the house at any point.
• A deck more than 200 square feet.
• Replacing joists, posts, beams or stairs.
• Replacing the guard railing.
• Replacing the decking boards, if the new boards are heavier than the old ones.

Any one of those is enough. A 120 square foot deck that's bolted to the house needs a permit, and so does a freestanding deck that's 36 inches off the ground at its low corner. The 30 inch rule is measured at any point, so on a sloped yard a deck that starts at grade by the back door can cross 30 inches at the far edge.

The guide also covers exterior concrete stairs, ramps, landings and structural deck repairs, so the same rules apply if you're rebuilding the steps off a deck or replacing rotten framing under an old one. It doesn't apply to apartment or condo buildings with three or more attached units on one lot, which go through the commercial process.

Decks that don't need a permit

A small, low, freestanding deck can skip the permit. Working from the guide's list, a deck needs no permit only when all of these are true at once:

• It's 200 square feet or less.
• It's 30 inches or less above grade at every point.
• It isn't attached to the house anywhere.
• It doesn't serve the front door.

Miss any one and you need a permit. Attaching a ledger board to the house is the one that catches people most, because it's the usual way to build a deck off a back door.

No permit doesn't mean no rules. The city's Building Permits page says it plainly: permit exempt does not mean code exempt. A deck that skips the permit still has to follow the building code, and the guide's own guard rule is a good example. Guards are required where the deck is 30 inches or more above grade measured 3 feet out from the deck edge, so a deck that's low at the house can still need a railing on its high side.

The city also notes that new building codes took effect on April 1, 2026, and the deck guide is written to the 2024 International Residential Code. If you're reusing plans or advice from a few years ago, check them against the current guide.

What you submit to get a deck permit

The guide lists what goes in with the application. All plans have to be drawn to scale, such as a quarter inch per foot, and sent as PDFs. They can be hand drawn.

• Permit application, with the deck's square footage and a note if other work is included, such as lights or outlets.
• Homeowner affidavit, if the homeowner is building it.
• Site plan showing the deck in relation to the house, its length and width, and its distance to the property lines and nearby structures.
• Plans: a floor plan of the framing (piers, posts, beams, joists, ledger, stairs and guards, with spans and spacing), a side view showing the height, post height, pier depth, guards and stairs, and the connection details.
• A before photo showing where the deck will go.
• The information sheet on page 5 of the guide, which asks for the wood species, member sizes, spans and pier diameters.

The plan check fee is due when you submit, and the city doesn't review an application until it's paid. For newer homes, the guide notes that an existing site plan may be available through a public records request, which can save drawing one from scratch.

Some decks need an engineer. The guide requires stamped plans from a Colorado registered engineer for, among others, multi-story or stacked decks, decks that hold a hot tub, beams hung from hangers, a ledger on a cantilevered bump-out like a bay window, specialty piers such as helical piers, a pergola sitting on the deck, and steel decks west of Overland Trail, which the guide places in a wind region above 140 mph.

The building rules your deck plans have to show

The guide pulls out the code rules that most often decide whether plans pass. These are the ones most homeowners ask about:

Pier size depends on how much deck each pier holds up. The guide calls this the tributary area and gives a chart: a pier carrying 20 square feet of deck needs a 12 inch diameter, 40 square feet needs 16 inches, 80 square feet needs 22 inches and 120 square feet needs 27 inches. That's why the plans have to show the tributary area for each pier.

Two smaller rules surprise people. Deck stairs need a wet-listed light at the top landing, and a new light has to be shielded and aimed down, which the guide calls a local amendment for dark skies. And for treated lumber, the guide says fasteners and connectors have to be ZMAX, stainless steel or hot dipped.

The five inspections on a Fort Collins deck

Once the permit is issued, work can start and inspections can be booked. The guide lists them in order:

1. Setbacks and footings. The pier holes are inspected before any concrete goes in.
2. Foundation. The post connections.
3. Rough frame. Called in before the decking boards go on, because the inspector needs to see every connection. If the deck uses hidden connectors, the guide says you'll need to schedule more than one rough frame inspection.
4. Rough electric, if there's wiring, before it's covered.
5. Final, plus final electric if there's wiring.

The order matters for scheduling. Concrete can't be poured until the pier holes pass, and the decking can't go down until the framing passes. A deck that skips an inspection can mean pulling up boards so the inspector can see the framing underneath.

Before the pier holes are dug, the ground has to be marked for utilities. Colorado 811 lists deck footings as covered digging and asks for two full business days' notice. Our Fort Collins fence rules post covers how the free locate works and why sprinkler lines aren't part of it.

Who can pull a deck permit in Fort Collins

Fort Collins licenses contractors by class, and the deck guide lists which classes can build decks: A, B, C, C2, D, D2 and MM. It notes that MM doesn't cover two-story decks. If you hire someone to build your deck, ask which City of Fort Collins license class they hold and check it's one of those.

Homeowners can build their own deck and pull the permit themselves with the homeowner affidavit the guide mentions. That puts the plans, the inspections and the code on you, the same as they would be on a contractor.

Either way, the permit holder is the person the inspector deals with. If a contractor pulls it, ask for the permit number so you can follow the inspections yourself. The city's Building Inspections page is where inspections are scheduled, and Building Services answers questions at 970-416-2740.

If the house is in Loveland, Windsor or Timnath, the deck permit comes from that city or town instead, with its own forms and fees. Unincorporated Larimer County is covered in the next section.

Decks outside Fort Collins city limits

If your house is in unincorporated Larimer County rather than the city, the county's rules apply. Larimer County's building permit guide (revised March 4, 2022) says a permit isn't required for a residential deck that's not more than 30 inches above grade at any point and doesn't serve a required exit door. A deck that's higher than 30 inches or serves a required exit door needs one.

That list is shorter than the city's. The county guide doesn't name size or attachment to the house as triggers the way the city's deck guide does, so ask the county Building Division at 970-498-7700 how they treat an attached or larger deck before you assume it's exempt.

The county also notes that land use code rules, such as setbacks, lot coverage and floodplain limits, apply even to structures that don't need a building permit. A deck near a property line or a ditch can still run into those, so check before the footings go in.

What a new deck costs

HomeAdvisor's deck cost guide (updated June 17, 2026) puts a typical new deck at $4,338 to $12,653. These are its published national ranges:

The permit figure is a national range. Fort Collins charges a plan check fee at submittal and the rest when the permit is issued, so ask Building Services for the fee on your deck's size and value.

For a quote, NoCo Services does decks and railings in Fort Collins and nearby cities like Windsor. Ask any builder to list whether the price includes the permit, the drawings, removal of an old deck, stairs and railings.