Residential Deck Requirements
12800 Ravine Parkway South
Cottage Grove, MN 55016
www.cottagegrovemn.gov
E-mail: building@cottagegrovemn.gov
Building/Zoning Permits are required for all deck projects to allow review of plan details and provide
construction inspections to assure structural stability and verification of setbacks from adjoining property lines.
Setbacks: All properties have setback areas from the property lines where a structure may not encroach. The
Community Development staff can provide you with a site plan to illustrate the project setback dimensions.
Plan Submittal Requirements: Design plans must be drawn to scale, preferably 1/4 inch, and illustrate the
following:
Site plan with distances to property lines
Size and depth of footings
Height and design of guards
Size and spacing of joists
Height of deck from grade
Type of decking material
Size and spacing of posts
Live Load: Decks must be designed to support a live load of 40 pounds per square foot.
Frost Footings: Frost footings are required for any deck attached to a structure that has frost footings. The
minimum depth to the base of the footing is 42 inches. Diameter depends upon design.
Decking Material: All wooden members of decks must be of treated or rot-resistant (such as redwood or
cedar) wood. All hardware used with treated wood must be ACQ compliant. All hardware must be properly
sized and secured. Composite materials must be certified by approved testing laboratories.
Posts: All posts must be anchored to prevent movement. Posts for decks over 60 inches high must be a
minimum of six inches by six inches square.
Beams: A one-foot maximum beam overhang from the edge of the post is allowed. Any splices must be made
over a post.
Ledger: Ledger boards must be bolted or lag screwed to solid material, such as interior rim joist, floor truss, sill
plate, etc. Manufactured I-joists, foam-filled rim joists, and wall sheathing material are not acceptable materials
to bolt into. Bolt ledger with a minimum of 3/8-inch bolts spaced 16 inches on center staggered top and bottom.
Flashing is required where the deck ledger is attached to the structure.
House Cantilever: A cantilevered area (boxed or bay area overhang, usually with a patio door) will not support
a deck structure. Additional design considerations and details will be required at these areas.
Joist Cantilever: Joists must not overhang the beam edge by more than two feet.
Guards: Decks more than 30 inches above grade must be enclosed by guards a minimum of 36 inches high.
Spindles/balusters must be spaced so that a four-inch sphere cannot pass between them. Stairways to decks
more than 30 inches above grade require guards and handrails a minimum of 34 inches in height.
Stairways: Minimum 36-inch wide stairway, maximum 7-3/4 inch rise, minimum 4-inch rise, minimum 10-inch
tread depth, and maximum 4-inch riser opening. All riser heights should be equal. The greatest riser height
must not exceed the smallest by more than 3/8 inch. Special attention should be given to the top and bottom
riser height design to assure that all of the risers are of equal size. Stairs with a total rise of 30 inches or more
above grade require 34 inch minimum height guards with a maximum 4-3/8 inch spindle spacing. Stair lighting
is required.
Handrails: A continuous handrail is required for stairways with four or more risers. Handrails must be installed
a minimum of 34 inches, to a maximum of 38 inches, above the tread nosing. The ends of the handrails must
be returned or terminated in the post. The handgrips must be 1-1/4 to 2 inches wide in a shape easy to grip.
Special Design Note: These requirements are for deck structures only. Additional considerations are required
if deck design is intended for a future covered porch or enclosure.
