I plan on replacing my 25 year old aluminum windows with some vinyl retrofits. The window guy at the local big box store told me I would get the best fit and a slightly larger window if I cut away the aluminum flanges ( I think that it what it's called) that protrude inward from the frame and install the window directly over the frame. After looking online, I can't find any reference to this being done. Is this a good idea? Thanks.
I hope I attached the photo correctly. The part he says to cut away is the metal that sticks out from frame. Basically, he told me to measure drywall to drywall because I'll cut away the portion of the frame that is not embedded in drywall.
I would go to some place that sells only doors and windows. The big box window guy could well be a retired house painter. And for sure don't buy your windows there. They may carry a quality name (like Pella) but will not be of the same quality.