conflict of clause regarding automatically shutting down make-up air

[sunyaer]

This is from Ontario Building Code division B:



This is the referred 3.2.4.13:


I take "prevent the circulation" as "shut down". So in a high-rise building, does the make-up air duct serves more than 1 storey? I would say YES, so 3.2.6.2.(5.1) would never apply, since high-rise building always has more than 1 storey, what am I missing?

 

[e hilton]

You’re missing some details. The first one talks about make-up air … bringing in outside air. Not recirculating systems. You want to bring in outside air to pressurize the hallways to keep smoke from getting into the halls and stairs.

 

[tmurray]

The system likely serves more than one storey, but the ductwork can be isolated (with smoke/fire dampers) so it doesn't.

The application is that if the system only serves on storey, it is good to go. If it serves more than one storey, you need to install smoke dampers to keep smoke out of adjacent spaces and allow the system to continue to run.