Before the window was installed, the team checked the rough opening size to make sure the window would fit. They also opened the window packaging and inspected the product.
The window was set in place and centered. Shims were set underneath both right and left sides as well as below the join — the example used in this video is actually two windows that were joined together at the factory. They then used screws to tack through the nailing flange in the top two corners and checked for level, plumb, and square again, before finally checking operation.
Checking for square and operation are two steps he emphasized as “super important” because a window that isn’t square will not operate properly. So, his team opened and closed the window and locked and unlocked the window multiple times to test its operation. Once they were satisfied with the window’s operation, they screwed in both sides and finally the top.