Originally Posted by
Darren Miller
Thinking about it again, somethings wrong. If fire rating is needed, then the foundation wall must also be fire-rated (it's supporting the fire-rated wall).
No, the intent is to keep the fire inside for two hours. You don't want a fire in that unit to burn down neighboring units.
There are several reasons for having fire rated walls, ceilings and floors within a structure.
Then there is fire rating based on distance to the property line to protect other structures - I believe that is the intent they are going for.
An example would be townhomes. There are not fire rated ceilings or floors (assuming slab on grade) in the town home, only fire retardant treated roof sheathing for 4' out from the fire rated partition separating the townhomes or a 30" high parapet extending up through the roof.
The intent is not to save the townhome which is one fire, the intent is to save the adjacent townhomes from that fire by delaying its movement for 1 or 2 hours, enough time to allow everyone to get out and the fire department to bring the fire under control and save the other units.
This happened recently in Sanford between here and Orlando a few months ago when a plane crashed into some townhomes. the fuselage hit one and the engines and wings took out the adjacent ones to each side.
The center townhome was destroyed in the fire, the two adjacent townhomes suffered considerable fire damage from the engines and fuel. the other townhomes to the side of those two were relatively undamaged - except for water damage due to firefighting needs. When the fire was out, there was a vacant area between two fire partitions and the two adjacent townhomes were burned out to the second floor. The other townhomes survived.
Just like it was supposed to do - the fire stopped at the fire rated partitions.