How labor contractor charges covered area

Aoa,
I'm a newbie in this field , any suggestion and guidance is highly appreciated.
I'm constructing a 39.5 x 26 feet for running a shop. The front side is (39.5) +6'(verandah). And the other 3 corners is 2'(shed). So after calculating covered area it becomes 1430sqft. Now my labor contractor asking me to include the walls height to be included in covered area. According to him it becomes 1565 sqft. So is he fooling me or this is how labor contractor charge?

Only covered area under roof slab will be calculated including shades whatsoever. No wall height should be calculated in covered area.

Hope this will be beneficial.

Rest we are at your disposal.

Regards

Team dSA

92-333-4220989