Fix it: Installing a replacement window

[DarkSkies]

9. Install. Place the window in the rough frame, see how it fits. You will have bought some shims ahead of time, or some mason lath to make shims with. Make sure you place the top plastic header and bottom plastic channel on ahead of time, unless you think it might be too tight. At that point, you might have to eliminate or modify them.

Generally, it's better to use all the parts they gave you, with the exception of their hardware. For windows or cabinet installs, I never use the screws they gave me. I use deck screws for their superior strength.

cut your shims