There is a maximum size limit of 50% of the gross floor area of the primary dwelling unit, or 1,000 square feet, whichever is more restrictive. The maximum building coverage for the zone district also applies to the entire property.
As an exception to this limit, an ADU in a basement or second floor may exceed the above allowance if the first floor is the same area. For example, an ADU in a basement may be up to 1,200 square feet if the first floor is 1,200 square feet.
If an ADU is part of a detached garage, the ADU square footage is counted separately from the footprint of the garage. For example, a detached garage of 800 square feet can potentially have an 800 square foot ADU above, and the ADU is only considered to be 800 square feet, not 1,600 square feet.