What is the MOST ACCURATE way to measure for replacement windows?
I have inherited a house built in the 'S. It has single pane aluminum slider windows that are useless. (most don't even lock) I want to replace them this summer with vinyl casement windows. What is the best most accurate way to measure for them, so I don't order and get stuck with windows I can't use. Do I measure the opening on the inside of the window? Would a member of the sales team come out and measure?