An image of what you are questioning will make your question clearer.

Without seeing the interior of the house it is difficult to tell how the slightly sloped roof is constructed. it could be 2x members spaces at 24" supported by walls and beams, or slightly sloped beams spaced the width of the windows with timber decking spanning between the beams.

The clearstory windows on the front of the house provide a clue to the location and spacing of the support members, but the photo is too small to really tell what the supporting members may be.

Do you have interior photos?

no interior photo. designing a MC-ish vaca home, slightly sloped roof & desire a low profile roof line. truss engineer is talking 24", 18" is my max, prefer 12". curious on how it is accomplished. thanks for your insight.

Steel.

For a mid-century modern house, stop thinking about trusses and focus on post and beam.

It will make all the difference.

thanks! building codes/inspector are dictating otherwise. 130mph wind rating is the cherry on the top. starting to accept the fact my sleek home will look like a character from south park.

Are you working with a structural engineer? An experienced structural engineer (or an architect), can give you many options to consider which meet local codes and conditions. Good luck!

Steel bar joists can be specified at your requested depth - they will simply be beefier than the "taller" truss.

We have 2' deep trusses as standard, but needed more headroom for the 13' shop garage door - so - the first 4 bar joists we ordered to only be 18" (or 14" - can't remember) and are functionally equivalent.

Our structural engineer is very good and works with most of the local modern architects.