There is a lot to know about constructing a deck to comply with Minnesota’s building code, how to apply for and obtain a permit, and how inspections are handled. We have a Residential Decks packet here that includes all of the information you need as well as the application materials for building a deck.
Much of the information is also provided on this web page, but you will need to refer to the packet for a complete understanding of what we need from you and how to design the deck to comply with the code.
You will submit a permit application and plans to Construction Services. Allow at least 3 days for review of the plans. So, if you and your crew plan to build your deck on a weekend, it’s a good idea to plan ahead, find out setback and other requirements early, and submit your plans a week or two in advance.
The cost of the permit will be based on the size of the deck. You can estimate your cost by entering the area of the deck in square feet here in the deck permit fee estimator. The actual fee will be determined at the time your application is reviewed.
Deck Fee Calculator
You will need two or three inspections, depending specifically on how your deck is configured, and those inspections need to be scheduled ahead of time on a weekday, so keep that in mind as you plan your project. You’ll find more details about inspections below and in the packet.
A permit is required if the deck is attached to the dwelling or is 30 inches (or more) above grade. A building permit application must be completed and submitted to Construction Services. Allow a minimum of 3 business days for review of the plans. You will be contacted when the building permit is ready to be issued. Cost of the permit is based upon the size of the deck. With your permit you will receive a copy of your approved plan. Please be aware that if you later decide to make changes to your plan, these changes must also be approved.
A Permit Application Checklist outlining all application requirements is provided with this handout and must be completed and submitted with your application. See pages within for sample Site Plans, Ledger Connection, Lateral Load Connection, Framing / Foundation Plan and Standard Details.
Always site specific. Check with Construction Services at 218-730-5240 for your project.
Deck height, measured to the underside of beam, may be 6’-9” with a 4x4 post, 8’ with a 4x6 post and up to 14 feet with a 6x6 or 8x8 post if all of the requirements of table R507.4 are followed. For decks beyond the parameters of the table, a complete design of the framing, connections and foundation by a Minnesota licensed structural engineer is required.
A multi-level or stacked deck is not addressed in the code and design must be by a Minnesota licensed engineer. If proposed deck does not require an engineer, footings must be sized to carry the load from all levels. Design for 42-pound live load plus 10-pound dead load, assuming 1500 psf soil bearing capacity.
All decks shall be designed to support a live load (people, furniture, grills, etc.) of 40 lbs per square foot, and a dead load (wood, decking, etc.) of 10 lbs per square foot (R301.4, R301.5).
See MINIMUM FOOTING SIZE table R507.3.1 for footing size based on soil bearing. If no soils report is provided, to document bearing capacity, assume soil bearing of 1500 See JOIST SPAN table R507.6 for minimum joist size, spacing requirements and cantilever maximums. See BEAM SPAN table R507.5 for beam size. Beam may cantilever post by 1/4 the adjacent beam span. Ask your lumber supplier about species and grade.
Joists shall be spaced 16” on center for perpendicular and 12” on center for diagonal 5/4” deck boards Joists shall be spaced 24” on center for perpendicular and 16” on center for diagonal 2X” deck boards Plastic composite deck boards to follow manufacturers specifications.
Please use table R502.3.3(2) for cantilever spans for balconies. Ground Snow Load for Duluth MN is 60 psf.
Different loads require different attachment. Please refer to the LEDGER ATTACHMENT REQUIREMENTS provided in this hand-out.
A minimum of two lateral load connections are required per deck. Please refer to the DECK LATERAL LOAD CONNECTION requirements provided in this handout.
All connections between deck and dwelling shall be weatherproof. Any cuts in the exterior finish shall be flashed. Flashing of the ledger at the point of connection to the house is especially critical (R703.8).
Footings are required for any deck attached to a dwelling or to any other structure that has frost footings. The minimum depth to the bottom of the footings is 60 inches. The footing bottom diameter shall be based upon the attached table R507.3.1. If the materials used for posts are not rated for ground contact, the concrete piers must protrude above grade a minimum of 6 inches.
Posts must be centered on the concrete piers and attached with a mechanical fastener (post base) and anchor bolt (or approved equal). Beams must be positively connected to the top of the posts. Options include a mechanical fastener (post cap) or notch the top of the post 3 inches (two 2x beam only) from one side and thru-bolt the beam with a minimum of (2) – ½ inch diameter bolts (two 2x8) or (3) – ½ inch diameter bolts (two 2x10 or greater). Splices in beams must be centered over a post. Each joist must be connected to the beam with the proper fastening method using nails, joist hangers or hurricane clips. Beam members shall be nailed or screwed together. Attach with a minimum of (2) – rows 10d common nails or (2) – rows #10 screws at 16 inches on center from each side, stagger. Split beam attachment to posts is not allowed.
Minimum width is 36 inches. Maximum riser height is 7¾ inches. Minimum tread depth is 10 inches. Treads with a depth less than 11 inches must have compliant nosing. Largest tread depth or riser height shall not exceed the smallest by more than 3/8 inch across the run of the stairs. Treads shall be level with a slope no greater than 2%. Lighting capable of illuminating the treads and landings is required, shall be located in the immediate vicinity of the top landing and may be activated from inside the dwelling (R303.7). There shall be a landing at the top and bottom of stairs. Landings must be as wide as the stairs they serve, have a minimum length of 36 inches in direction of travel and have a slope no steeper than one-unit vertical in 48 inches horizontal (2% slope). R311.7
Stairways having 4 or more risers shall have at least 1 handrail. The top of the handrail shall not be less than 34 inches or more than 38 inches above the nosing of the treads (to the top of the gripping surface). Handrails shall be continuous for the full length of the stairs and shall protrude from the adjoining surface by at least 1½ inches, but no more than 4½ inches, and the ends shall be returned or terminated into posts. Handrails with a circular cross section shall have an outside diameter of not less than 1¼ inches or more than 2 inches. Other handrails may be acceptable. See the specific code language to be sure your handrail does comply R311.7.8.
A guardrail is required on all decks or any portion of a deck more than 30 inches above grade or above a lower deck. Deck guardrails must be a minimum of 36 inches high. Open guardrails on decks must have intermediate rails (balusters) or an ornamental pattern that a 4-inch sphere cannot pass through. Guardrails on open sides of stairs cannot have an opening between balusters that a 4-3/8-inch sphere can pass through (R312).
Header beams and joists that frame into beams shall be supported by approved framing anchors such as joist hangers. Beams supporting deck joists shall not be supported on deck ledgers or band joists. Posts shall be attached to concrete piers with a post base and anchor bolt (or approved equal). Installation of these framing anchors shall be in accordance with the manufacturer’s installation instructions; typically, special nails are required. Note: Decks must be positively anchored to the primary structure or be self-supporting. Please see drawings provided in packet.
Fasteners for pressure-preservative wood shall be hot dipped zinc coated galvanized steel (HDG), stainless steel, silicon bronze or copper. Ask your materials supplier for an approved fastener (R317.3.1). Screws cannot be used to attach joist hangers unless specifically approved for such application.
You must call for a scheduled appointment time (please try to schedule inspections a minimum of 24 hours in advance). The approved plan must be on site for all inspections. Typically, 3 inspections are required:
- Footings – These will be checked for proper diameter, depth, belled bottom, a flat surface at the base, and no water in the holes. The form (sonotube) and reinforcement must be in place. The post bases and anchor bolts (or approved equal) must be on-site.
- Framing – If your deck surface is 4 feet or closer to the ground, you must pass a framing inspection before the decking material may be applied to the deck surface. Structural integrity and proper attachment of all connectors will be inspected.
- Final – For decks that are 4 feet or greater off the ground, framing and final inspections may be completed together. A final inspection must be completed to be sure that the deck complies with the current Minnesota State Building Code.