The math does for me on most building projects. Not helped, already being mathematically challenged, by the govt moving from imperial to metric before I had a firm grasp on the basics. Now I work in a mish~mash & the results are...original.
As for storage ~ the bane of my life. We've never, ever had enough & I am on the man's case so I can shut the door on the junk we can't throw out!

As for storage ~ the bane of my life. We've never, ever had enough & I am on the man's case so I can shut the door on the junk we can't throw out!