Fire Separation Between Dwelling Units Roof

Buildings can sit directly on the property line provided they meet the fire resistance requirements and do not have roof overhangs or exterior wall openings.

Fire separation between dwelling units roof.

Dwelling units in two family dwellings must be separated from each other by wall and floor assemblies having a minimum 1 hour fire resistance rating. Fire resistance shall run from foundation to underneath the roof sheathing. New exception allows for the reduction of the 1 hour fire resistance rating of the exterior wall assembly between the building and the exterior area of assisted rescue provided the building is equipped throughout with either a nfpa 13 or 13r automatic sprinkler. Fire area appears in the building code mostly in chapter 9 where it is used as a threshold for requiring either fire separation or fire sprinkler systems.

When properly constructed a gypsum area separation wall serves to prevent a fire in one residential unit from breaching into an adjoining unit for at least 2 hours which is enough time occupants to evacuate and for firefighters to successfully extinguish many fires. Other forms of construction may also be acceptable provided that they achieve this intent. O the closest interior lot line o the centerline of a street or public way o an imaginary line between two buildings on the same lot errata. New exception decrease reduction in fire rating.

Since many of the fire suppression system thresholds see ibc section 903 2 are based upon the fire area separation of a single occupancy into small fire areas can be an acceptable method for avoiding the use of sprinklers. This is a classic type of design decision. For example section 903 2 9 states that one threshold of sprinklering the entire building is when such a building contains a group s 1 fire area of greater than 12 000 square feet. Exterior walls of dwellings garages and accessory buildings must maintain a 5 minimum separation distance from the property line or otherwise be fire protected.

Walls less than 5 from the property line are required to have a one hour fire rating. Footnote h group u carports and private garages with fsd of 5 feet do not require fire rating. 4 e40 15 ibc 1009 7 2 separation.