Alamo Heights is an independent city, so San Antonio's ADU rules do not apply. Its zoning code, as published, allows detached servant or caretaker quarters for people employed on the premises and says accessory buildings are not to be rented or used as a separate domicile. As of October 2026, that makes a rentable ADU difficult; confirm with the city before designing.
What can I build behind my house?
Accessory buildings for uses tied to the main home, such as a garage, pool house or quarters for household employees. A guest suite used by your own household may be possible within those limits. We confirm the intended use with the city before design so the permit matches it.
Does an accessory building affect my floor area?
Yes. The code's floor area ratio definition counts accessory buildings such as pool houses, guest houses and second units toward gross floor area. On lots already near the limit, that can rule out a new structure.
How many unrelated people can live in a unit?
The code's family definition limits unrelated occupants to two individuals, which is tighter than many neighboring cities.
What if I want an income unit?
Alamo Heights is a hard place for that today. Owners who want a permitted rental ADU usually do better on a lot inside San Antonio, where the city allows one ADU per property with an owner-occupancy affidavit. See the San Antonio owner-occupancy rule.