All districts
Detached garages, sheds and ordinary accessory buildings belong in side or rear yards, not the front or required side yard. Residential side/rear lot-line minimums are 5 feet on lots below 2 acres and 20 feet on lots at least 2 acres; nonresidential minimum is 10 feet (§ 138-10.102).
Combined detached accessory floor-area caps by parcel acres: below 1 acre 1,000 square feet; 1–1.99 acres 1,200; 2–2.99 acres 1,400; 3–3.99 acres 1,600; 4–4.99 acres 1,800; at least 5 acres 2,000. Combined attached and detached accessory floor area also cannot exceed the main building’s first- and second-floor area. Qualifying gazebos up to 180 square feet are excluded from the accessory-area cap (§ 138-10.106).
Detached residential accessory height is one story, 14 feet below 4/12 roof pitch or 16 feet with pitch at least 4/12. Attached accessory height is the lesser of district maximum and principal-building height. Structures within 10 feet count as attached for setbacks and coverage (§ 138-10.101).
On a residential corner lot, § 138-10.103 requires the greater of: 10 feet from a side-street right-of-way or utility easement; or the required front setback of a residential lot within 300 feet, on the same or opposite side of the street, that has a front-yard relationship to that street.
Attached and detached decks use detached-structure setbacks; a roof less than 50% open within 10 feet uses principal setbacks. Front decks have the specific limited exception in § 138-10.102.A.1. Roof structures at least 50% open are excluded from coverage (§ 138-10.100.D). Small accessory structures up to 200 square feet are exempt from site-plan review; building-permit requirements remain separate (§ 138-2.200.B).