It depends entirely if you are replacing the door with a "new contstruction" patio door in which case your only option is to remove the siding and replace the flashing....

Or if you are installing a "replacement door" in which case you will be simply installing a 'replacement' tyoe door in an existing opening, much like one would install a replacement window...

I am going to install an Anderson 400 Series French Single Swing. Looks like either removing all the surrounding siding or just releasing all the surrounding siding enough to get access. The siding is 10 years old and I am worried that it may be too brittle to be pushing around if I work around it by just releasing the edges. So I guess I will pop off the siding and number it for reinstall. I should get a better flashing job done this way too.

I live in a condo and I'm replacing the exterior sliding doors. The building has vinle siding that I can't remove. Do I need to use the flanges on an Andersen replacement door or can I install without. The frame will be going in from the inside up against the old wood and aluminum trim cover.

Can you recommend some good to better patio sliding doors cinsiderations: cost and quality