one sided 2 hour fire wall

[Jambruins]

I am designing a new apartment unit on the back of an existing 2 unit apartment building. It can be considered a townhouse building because each unit will have two sides with exterior walls.

What is the best way to get a 2 hour fire wall without having to redo the rear wall of the existing two units.

The new unit could have the roof extend up higher up than the existing roof or be lower than the existing roof.

Thanks for the help.

 

[Yankee Chronicler]

There is no such thing as a one-sided 2-hour fire wall.

 

[mtlogcabin]

Look at fire rated shaft construction listings. They are rated from both sides but can be built from one side

2-Hour Fire Rated Shaft Construction​

2-hour fire-rated shaft construction is required for shafts connecting four stories or more in buildings, according to the 2021 International Building Code (IBC).34 National Gypsum Company recommends the area separation wall system, UL design U347, for 2-hour fire-rated shaft enclosures.3 This system consists of two 1-inch thick shaftliner panels friction fit between 2-inch H-studs with a wood or steel stud flanking wall on one or both sides separated by a minimum 3/4-inch air space.3 The H-studs are clipped to the flanking walls with aluminum clips that melt during a fire event, allowing for the collapse of the fire-exposed unit without compromising the fire wall.

 

[steveray]

You could probably get there with a shaftwall system....But it might not be easy...