Duluth Deck Guide: Footings, Permits, Rules (2026)

Updated October 25, 2026. This guide is general information, not legal or engineering advice. Rules change, so confirm with the agency listed before you start work.

Quick reference

Topic	Duluth, MN	Superior, WI
Footing depth	60 in. below grade	Below frost line or at least 48 in.
Guards required	Over 30 in. above grade; 36 in. tall; 4 in. sphere	Over 24 in. above grade; 36 in. tall
Stairs	7-3/4 in. max riser, 10 in. min tread; handrail at 4+ risers	8 in. max riser, 9 in. min tread
Who builds	Licensed residential contractor if more than one special skill	City contractor registration; state Dwelling Contractor certification to pull permits
Permit office	Construction Services and Inspections, City Hall	City of Superior Building Inspection
Climate	Jan. mean about 11°F; about 90 in. of snow a year	About 56 in. of snow a year

How deep do deck footings go in Duluth?

Sixty inches. Minnesota's building code splits the state into two frost zones, and St. Louis County is in Zone I, where the minimum footing depth is five feet; much of southern Minnesota is in Zone II at three and a half. The rule allows shallower footings only when an engineer competent in soil mechanics shows evidence they'll work. Duluth's deck page states the frost depth as 60 inches below grade, and Hermantown lists the same. In Duluth, the footing inspection checks diameter, depth, the base and that no water is standing in the hole, and it happens before concrete is poured.

When does a Duluth deck need a permit?

The City of Duluth requires a permit for decks attached to a building, more than 30 inches above grade, or part of an accessible route. Freestanding platforms no more than 30 inches up and without frost-depth footings don't need one. Applications are made online at least two weeks before work starts and include a site plan with zoning setbacks and drawings of the deck. Simple rectangular decks can use the fill-in sheets in the city's packet; complex decks and decks with roofs need full plans. Shoreland permits may also apply near the lake and river.

What inspections should you expect?

Footings, before concrete, with forms and reinforcement in place and post bases on site
Framing: posts and beams, ledger, lateral load connections, joists and decking
Final, for compliance with the Minnesota State Building Code

The permit holder schedules each inspection at least 24 hours ahead, and the approved plans must be on site.

What does the Duluth deck packet require?

A ledger of at least 2x8, attached with half-inch lag screws or through-bolts with washers, and corrosion-resistant flashing. No attaching to brick veneer.
At least two lateral load connections between the deck and the house.
Span tables based on a 40 psf live load and 10 psf dead load.
Diagonal or corner bracing on decks more than 6 feet above grade, and a full design by a Minnesota licensed structural engineer for decks more than 14 feet up.
Guards on any surface more than 30 inches above grade, at least 36 inches tall, with 4x4 posts no more than 6 feet apart.
Stairs at least 36 inches wide, with landings top and bottom and a light near the top.

Does a Minnesota deck builder need a license?

The Minnesota Department of Labor and Industry says anyone who contracts directly with a homeowner for work in more than one special skill must hold a residential building contractor or residential remodeler license. A contractor with gross annual receipts under $15,000 can instead hold a Certificate of Exemption. DLI's consumer guide adds that a number beginning with “IR” is a registration, not a license, and that only homeowners who hired a licensed contractor can seek money from the Contractor Recovery Fund, which pays up to $75,000 per claim. Look up any license on DLI's website before you sign.

What should the contract cover?

DLI recommends a specific written contract: materials with brands and grades, start and completion dates, written change orders signed by both sides, a modest down payment with later payments tied to progress, and a holdback until you've inspected the work. It also suggests that the contractor obtain the permits, which makes them responsible for code compliance. Subcontractors and suppliers who aren't paid can file a mechanic's lien, so collect lien waivers as you pay and full waivers before the final payment.

How is Superior different?

Superior follows Wisconsin's Uniform Dwelling Code. Its deck appendix calls for footings below the frost line or at least 48 inches below grade, guards on decks more than 24 inches above grade, and stairs with an 8-inch maximum riser and 9-inch minimum tread. Under SPS 305.31, a building permit for a one- or two-family home requires a Dwelling Contractor certification and a certified Qualifier, and the City of Superior separately requires contractors to register with the city.

Questions to ask a builder

What's your Minnesota license number (or Wisconsin certification, for Superior), and are you insured?
Who pulls the permit, and does the deck need an engineer?
How deep will the footings go, and how will the ledger and lateral connections be done?
Will you provide lien waivers with each payment?

Common questions

How deep do deck footings need to be in Duluth?

At least 60 inches below grade. St. Louis County is in Minnesota's Zone I, where the code's minimum footing depth is five feet.

At what height does a Duluth deck need a guard?

Guards are required on any deck surface more than 30 inches above grade, at least 36 inches tall. In Superior, Wisconsin's code requires them above 24 inches.

Who issues deck permits in Duluth?

Construction Services and Inspections, Room 100, City Hall, 411 West First Street. Hermantown, Proctor and Superior issue their own.

Duluth deck guide (2026)