There is a way to get the square feet of your job but it will calculate for each group (using 'part summations') instead of total for the whole order.
The way to do this is to create a new part on each of your products for the purpose of adding up the square feet of the product. For example if it's for slab door that's an easy one. You'll just need to multiply the height and width to get the square feet of that product (don't forget to divide by 144 to convert feet to inches, I didn't show that in the image below):
