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RE: Town Home Lateral Loads

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That is how we have done it in the past. Then there are no drag forces. However, if I do that, I don't have enough seismic separation between units. I think the gap is 2" between framing. So it will be less after sheet rockis applied.

I agree. With insufficient seismic separation and no tied between units, how do you provide for deflection compatibility between units and prevent pounding at the floor? I think building them this way is foolishand the building official just doesn't understand. He wants me to enforce a fire separtion between units but then ignore the seismic separtion requirement. In the past we have always designed these as one building with continuous exterior double top plates through the air gap at a minimum, if not continuous floor sheathingthrough the length of the building. I have never seen a single building built where the floor diaphragm or double top plates were not continuous. This has been a recent change at this particular jurisdiction by the building official. An adjacent jurisdiction allows continuous floor sheathing and top plates at the exterior.

You are righton theseparation, 2" max. And as I replied to Bill above, I also feel this is foolish. This is a fire issue. The calculations are not a problem, it is a fire issue the building official is concerned with. Ifeel the risk of fire spreading to an adjacent unit through 3/4" floor sheathing orcontinuous exterior double top platesis a minimal concern compared to the structural problems you create. If he truly wants a separation there should a parapet between units on the roof as well. It seems to me like this is selective code enforcement with a limited understanding of how you are sacrificing structural integrity.

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