Testing on Friday- Not sure on my vignette

[pugzrool]

I am testing this Friday and have been going working on the 4.0 practice program online and am not 100% sure about my solution...

Originally, I had the max duct / joist combo at the lab only, but then was double checking the plan and noticed that there is a duct going from the lab to the 2nd story mechanical space and then from there to the 2nd floor space... Because of this I went ahead and raised the joists of the lab so that the duct could pass from the lab to the mechanical space to the 2nd floor plenum... am I doing this right?

[thd7t]

Do not raise the roof to allow the duct to pass through.

Also, your first floor rated corridor wall is not going to the floor (this is clearly a slip up, but keep an eye out for that kind of thing).

Do the 3.1 vignette. It's very helpful.

[pugzrool]

Do not raise the roof to allow the duct to pass through.

But I thought that we had to take into account the ability for a duct to pass from one space to another? IE if a duct is going from one space to another the duct would still need to be above the 8" space for lights? And as the ceiling height is fixed, the only way to do that would be to raise the ceiling joists?

Or is it because the duct is going through an intermediary space and not going directly from one to the other... ie it is going through the mechanical room and not directly from the lab to the 2nd floor?

In Dorfs solution guide it says that when a duct is passing from one volume to another then the volumes can't be treated separately.. this was in their sample vignette 2...

Can anyone give any more insight into this?

[thd7t]

You are overthinking this. The mechanical room acts as a chase. Ducts come out of the side of it at whatever elevation they need. Raising the roof like this would be too inefficient, even for an NCARB vignette!