Installing hurricane impact windows to code requires you to replace the Buck Frame of the opening. The Notice of Acceptance in Miami (product approval) is very clear on this. The impact windows must be installed the same way they were tested by the manufacturer. In most South Florida homes, the existing Buck Frame is often thinner than the one the product was tested with. The Buck Frame serves as an “energy load transfer”. This means it transfers the impact of a projectile from the glass of the window to the frame of the window, and then to the concrete wall the window is installed to. This ripple effect needs to be continuous and sound for the windows to perform against a hurricane or tropical system.