I am building my own house in SE Texas and wanted to
ask if anyone has any concerns about the HVAC Ducts I am

House is a two-story on a slab. I am having my home
insulated with icynene so it will have a very strong
moisture barrier.

The 1st floor ceiling/2nd floor is 18" open wood trusses.
The airhandler will be on the first floor - floor and
the ducts will be distributed thru the open wood

The ducts will be made out of 1.5" ductboard on 3 sides
and use the plywood floor for the 4th side. None of
the 4 sides will be next to an UNconditioned space.

Is this OK?

If not, why & what solution do you recommend?