Originally Posted by
John Arnold
It's a row home, at the end of the row.
That's why.
There is likely less than 5 feet to the property line, right?
The fire rating is determined on the distance from the property line, and the floor is being treated like a wall (which means the wall should also be two hours for the same reason). I'm going with the '2 hours' based on what they said, not looking it up to see if '1 hour' would suffice, just commenting that the wall and floor should be the same the fire rating based on distance to the property line.
If he constructed a block foundation wall around the addition, he would likely not need to have any fire rating to the floor system. If it is that small (for a laundry room), I would recommend doing that is this will eliminate long term problems related to the gypsum board being under the floor and exposed to the weather, plus, any penetration through the floor would need to be treated as a fire rated penetration and would require expensive fire stopping. He would have to do the math to see which is less $ and which is less trouble - the two might not be the same, in which case he would need to select the choice which best suits his needs and capabilities.