General Definition
- Under the IBC, Group U Occupancy is a classification for buildings or structures not typically used for human habitation but instead for incidental, secondary, or accessory uses.
- The BSL does not have an exact equivalent for IBC Group U, but similar classifications exist for non-habitable and accessory structures based on their use, fire risk, and construction type.
IBC Utility and Miscellaneous Group U Occupancy
- Agricultural buildings
- Aircraft hangars, accessory to a one- or two-family residence (see Section 412.4)
- Barns
- Carports
- Communication equipment structures with a gross floor area of less than 1,500 square feet (139 m2)
- Fences more than 6 feet (1829 mm) in height
- Grain silos, accessory to a residential occupancy
- Livestock shelters
- Private garages
- Retaining walls
- Sheds
- Stables
- Tanks
- Towers
- Greenhouses not classified as another occupancy shall be classified as Use Group U.
These structures typically have minimal fire and life safety requirements since they do not house occupants in the same manner as other groups.
BSL Equivalent to IBC Group U Occupancy
The BSL does not have an exact equivalent for IBC Group U, but similar classifications exist for non-habitable and accessory structures based on their use, fire risk, and construction type:
| IBC Group U Use | BSL Equivalent | Notes |
| Agricultural buildings, barns, livestock shelters, stables | 畜舎 (Chikusha – Livestock Housing) / 農業施設 (Nōgyō Shisetsu – Agricultural Facility) | Includes barns, farm storage, and animal enclosures |
| Carports, private garages | 車庫 (Shako – Garage) | May be attached to residences or separate buildings |
| Fences over 7 feet | 工作物 (Kōsaku-butsu – Structure/Installation) | Large fences and walls require permits |
| Greenhouses (non-commercial) | 温室 (Onshitsu – Greenhouse) | Commercial greenhouses fall under factory/agriculture regulations |
| Retaining walls | 擁壁 (Yōheki – Retaining Wall) | Subject to engineering and safety regulations |
| Sheds, storage structures | 物置 (Monooki – Storage Shed) / 倉庫 (Sōko – Warehouse) | Large storage sheds may need permits |
| Towers (radio, observation, water towers, etc.) | 塔 (Tō – Tower) / 特殊建築物 (Tokushu Kenchikubutsu – Special Structures) | Classified based on height, function, and structural requirements |
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Key Differences
- IBC Group U is a broad category, covering utility, agricultural, and storage structures under one classification.
- BSL classifies buildings based on their specific use, meaning that garages, sheds, greenhouses, and fences each fall under separate categories.
- Fire Safety & Structural Standards:
- IBC treats Group U as low-risk, with fewer fire protection requirements.
- BSL applies specific regulations per structure type, especially if near residential or commercial zones.