1 Hour Fire Wall In The Attic Of A Duplex

On a recent project in urbana the town houses only required a separation barrier wall between units and the duplex units required a full fire separation wall with fire proof sheathing and sealant.

1 hour fire wall in the attic of a duplex.

It is unlikely with a total burn out that a one hour wall will be able to survive once the first wall collapses. 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. It must extend from foundation to underside of roof sheathing. These wall assembly files are used for planning and estimation purposes for many ul wall types such as fire rated wall assemblies.

A 1 hour fire rating for the wall separating the units which is usually 5 8 type x drywall is required. The duplex will be 28 x about 60 long with the building split down the middle to make two 14 x60 units. Here s how it is specified in the residential edition of the florida building code fbc and the international residential code irc. This leaves you free to use whatever plumbing electrical insulation and finishes you want for the walls in each unit.

And three exceptions have been added over the years for a duplex with an automatic sprinkler system fire rated ceilings or a screen enclosure. A one hour fire rated unit separation wall is allowed for duplexes or for multi unit buildings that are equipped with approved fire sprinklers. 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. 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. If doing a remodel on a two family dwelling.