1 Hour Fire Wall In The Attic Of A Duplex

It must extend from foundation to underside of roof sheathing.

1 hour fire wall in the attic of a duplex. Here s how it is specified in the residential edition of the florida building code fbc and the international residential code irc. These wall assembly files are used for planning and estimation purposes for many ul wall types such as fire rated wall assemblies. And three exceptions have been added over the years for a duplex with an automatic sprinkler system fire rated ceilings or a screen enclosure. It is unlikely with a total burn out that a one hour wall will be able to survive once the first wall collapses.

Usg provides resources here for our ul wall assemblies for seamless integration into any construction project. Fire resistance shall run from foundation to underneath the roof sheathing. For some reason they must think the the town house is safer than a duplex even when attached to the end of 4 town houses. This leaves you free to use whatever plumbing electrical insulation and finishes you want for the walls in each unit.

A one hour fire rated unit separation wall is allowed for duplexes or for multi unit buildings that are equipped with approved fire sprinklers. If doing a remodel on a two family dwelling. Fire rated assemblies two family dwellings 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. This typical one hour fire rated wall assembly uses just a single 2x4 stud wall with fiberglass in the stud bays and 5 8 inch gypsum board on both faces.

The duplex will be 28 x about 60 long with the building split down the middle to make two 14 x60 units. In my experience the best way to make this work is with a two hour fire barrier wall that locates all of the fire resistance in the 2 of gypsum board panels and 3 4 airspaces in the middle of the assembly. A 1 hour fire rating for the wall separating the units which is usually 5 8 type x drywall is required.