Your lower cabinets, once topped with your solid surface , will have a height of 36 inches
108 inches is your ceiling height
-36 for the lower cabs and top
=72 inches
-18 INCHES FOR BACK SPLASH
= 54 INCHES remaining, TO HIT THE CEILING
- 48" FOR can upper cabinet
= 6 " open at top
So you add that flat, clean 6" TRIM AT THE TOP of those upper cabinets. When they install it? they scribe to the ceiling for a clean finish minus ugly gaps.
Or?
You build a FLUSH 6 inch soffit Flush to the cabinet box. And you use a 42 inch cabinet
A 36" upper with a useless 12 inc cabinet added? Will cost more.....is harder to perfect.
Don't do it
Q
the details on cabinet size for 9' ceiling
Q