Collierville, TN Accessory Structures: ADU Rules (2026)

Collierville Code of Ordinances § 151.024(M) governs accessory residential uses built in conjunction with a principal residential use, the town's version of the granny flat or carriage house. Section 151.003 defines the use as a second home or dwelling on the same lot as a primary, usually larger, home, with a kitchen complete with cooking facilities, at least one bathroom, and sleeping and living arrangements. Section 151.025(B)(1) exempts accessory residential housing from the general accessory-use section, so § 151.024(M) is the operative text.

Location comes first. The use or structure must sit within Special Areas 3, 4, 5, 6, 8, and 9 of the Downtown Collierville Small Area Plan. It must be accessory to an existing principal dwelling, and nothing prevents the unit from being located within or inside the principal structure. Mobile homes, recreational vehicles and travel trailers do not qualify.

Size is a floor and a ceiling. The unit must be at least 400 square feet but cannot exceed the lesser of 800 square feet or 50% of the gross floor area of the principal dwelling unit. Only one is allowed per lot. Parking is a range: at least one but not more than two off-street spaces, in addition to the required off-street parking serving the principal use.

Density and structure counts work in opposite directions. The unit does not count toward any maximum residential density requirement, but it does count toward any maximum number of accessory structures on a lot. Item (8) requires durable exterior building materials that are the same or higher quality as surrounding developments. Where the principal structure is predominately brick or stone, smooth wood or fibrous cement siding is appropriate to reinforce the ancillary and subordinate nature of the unit.

Items (9) and (10) add a no-sale rule and a rental limit, both backed by proof of deed restrictions before building permits. Units above non-residential uses are a separate category under § 151.003, developed in accordance with the standards in the code of ordinances.