[Zeke]

A lot of members here remember that I sold and installed windows as a business up until the Great Recession killed it. I have installed some windows this year, but not like I used to, like a several hundred per year as a lone wolf installer.

Measuring is not tough. The real trick is to criss cross the opening you intend to leave in place to determine if it's a true 90º rectangle. After that, deduct what the factory recommends.

Some window companies have a line of stock sizes intended for new installations. Most vinyl windows are built to order at no additional cost because, 1) there are so many options that having all of those in JUST ONE SIZE on the shelf would take up a LOT of space, and 2) the factory is gonna build a certain number of windows every shift no matter where they are going. 3 to you, 10 to the next guy and so on.

Retrofitting is encouraged over ripping out the entire existing jamb and that's because the jamb is flashed behind the brick to keep moisture out. Don't break that seal unless it's broken.

If you go to my local distributor's site (1stwindows.com), you can glean a hell of a lot of info for free and not even have to sign up. How to measure, install, the whole ball of wax. He is set up to mostly sell to DIYer's and smaller contractors.

Funny, but hot links seem to be disabled.