1 hour horizontal assembly in existing building

[emcc]

I'm working on an existing wood framed building. In order to meet chapter 10 of the existing building code a sprinkler system needs to be added. The fire pump room is located on the lowest level with a floor above. What is the most economical way to achieve a one hour horizontal separation for above the fire pump room? Most of the floor/ceiling assemblies I can find require a topping mixture between the finished floor and the subfloor. It would be preferable to not have to do any retrofitting to the floor above. I would appreciate any suggestions! Thanks!

 

[JPohling]

If your just trying to provide a rated separation at the fire pump room and do not require the existing floor ceiling assembly to be rated then just construct it with a horizontal rated wall that matches the rated wall assembly. essentially a rated hard lid ceiling. This is most commonly done with corridors and would be known as a tunnel corridor. If you are tight to the structure above you can use a horizontal shaft wall assembly so you can construct only from below.

 

[RLGA]

What system is used for the floor joists?

 

[Paul Sweet]

Gypsum Association FC5406 uses 2 layers of 5/8" type X gypsum board for a ceiling which provides one hour fire resistance protection for
framing above.

 

[mtlogcabin]

If your just trying to provide a rated separation at the fire pump room and do not require the existing floor ceiling assembly to be rated then just construct it with a horizontal rated wall that matches the rated wall assembly. essentially a rated hard lid ceiling. This is most commonly done with corridors and would be known as a tunnel corridor. If you are tight to the structure above you can use a horizontal shaft wall assembly so you can construct only from below.

You cannot use a wall corridor assembly (fire partition) as a ceiling assembly except in a corridor. 708.4 exceptions are where you will find when and how the ceiling is to be constructed.

913.2.1 Protection of fire pump rooms.
Fire pumps shall be located in rooms that are separated from all other areas of the building by 2-hour fire barriers constructed in accordance with Section 707 or 2-hour horizontal assemblies constructed in accordance with Section 711, or both.

Exceptions:

1. In other than high-rise buildings, separation by 1-hour fire barriers constructed in accordance with Section 707 or 1-hour horizontal assemblies constructed in accordance with Section 711, or both, shall be permitted in buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1 or 903.3.1.2.

2. Separation is not required for fire pumps physically separated in accordance with NFPA 20.

Not sure when you will have a fire pump and not have an automatic sprinkler system installed.