Direct Answer
In Detroit, retaining wall construction work generally requires a permit when the project exceeds $600 or involves system replacements. Your licensed contractor should pull the permit — if they ask you to pull it yourself, that's a red flag. Unpermitted work can cause problems when selling your home.
Full Explanation
Detroit follows MI state building codes administered by the local building department. Permit fees vary by project value. All inspections must be scheduled through the Detroit building department. Keep all permit documentation — required for home resale disclosure.
Local Factors in Detroit
📍MI permit threshold: $600
📍Detroit building department issues local permits
📍Sales tax on materials: 6%
📍Permit records are public and transfer with the home