Ductwork resources?

I've just got someone to pull a mechanical permit so I can run new ductwork to kitchen and 2nd floor bedroom (both new additions). I have not touched a self tapping screw in 15 years. So all the help I can get would be appreciated.

I've got 19x 8 square duct terminating 12 feet from plen.

Anyone have experience or can direct to web? Much appreciated.

duct

What is the question? If you have a permit, then you should have the required sizes on it, assuming the furnace is large enough for the additional load.