1 Hour Fire Wall In The Attic Of A Duplex

I know that i need a 1 hour fire wall separating them from the foundation to the bottom of the roof.

1 hour fire wall in the attic of a duplex. 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. These wall assembly files are used for planning and estimation purposes for many ul wall types such as fire rated wall assemblies. Here s how it is specified in the residential edition of the florida building code fbc and the international residential code irc. A 1 hour fire rating for the wall separating the units which is usually 5 8 type x drywall is required.

Usg provides resources here for our ul wall assemblies for seamless integration into any construction project. And three exceptions have been added over the years for a duplex with an automatic sprinkler system fire rated ceilings or a screen enclosure. 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. 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.

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. 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. Where back to back walls are provided the original intent recognised that collapse on one side with unprotected steel structure for instance could occur within 10 minutes.

This leaves you free to use whatever plumbing electrical insulation and finishes you want for the walls in each unit. It is unlikely with a total burn out that a one hour wall will be able to survive once the first wall collapses. Fire resistance shall run from foundation to underneath the roof sheathing.