Is an Engineer Required for My Deck Project in Michigan?

Michigan cities — Detroit, Grand Rapids, Warren, Sterling Heights — generally require an engineer-sealed plan set for any deck that leaves the prescriptive path, and the PE seal is the standard requirement for the structural sheets. The seal must show the engineer's name, Michigan PE number, and date, with the engineer in responsible charge. Simple ground-level decks can often be permitted from the prescriptive span tables, but ledger-attached decks, decks over 30 inches above grade, and decks carrying a hot tub or roof load are treated as engineered work in Michigan. Owner-builders don't escape the requirement: the building department asks for the seal regardless of who drew the plans, and the engineer must design the deck for deep frost and lake-effect conditions.

The engineer designs the footings for footings below deep frost penetration — the engineer sets piers deep enough that freeze cycles never lift the deck, and details the ledger connection with ledger connections checked for snow load — Michigan's heavy snow reaches covered decks, and the ledger must be verified to carry it. Guards, stairs, and lateral bracing go on the sealed plan set — guard height and infill spacing, stair stringer sizing, and the bracing that keeps the deck from racking under deep frost and lake-effect conditions. Bring a plot plan with setbacks, the deck's dimensions and height above grade, and photos of the house wall where the ledger will attach. Michigan's deep frost lifts shallow decks — the engineer designs pier depth and drainage for the coldest winters, not the average one.

Use this checklist before engaging an engineer for your deck: • Engineer of record holds an active Michigan PE license, verifiable on the state roster • Footings designed for deep frost and lake-effect conditions on the lot • Ledger connection detailed to the house band joist, never the veneer • Lateral bracing and hold-down designed for deep frost and lake-effect conditions • Guards and stairs drawn to code (guard height, infill spacing, stringers) • Hot tub or roof loads called out and framed for where the deck carries them • Post bases and hardware specified for the local exposure • Engineer confirms they'll respond to plan-check corrections on sealed sheets