Abstract: A method of installing a fenestration unit in a composite panel using a foam material, and to a composite panel with the fenestration unit installed using a foam material, where the foam material is the primary attachment structure. A rough opening is created in the composite panel where the rough opening has a perimeter larger than a perimeter of the frame of the fenestration unit. Then the fenestration unit is positioned in the rough opening with a space between the perimeter of the frame of the fenestration unit and the perimeter of the rough opening of the composite panel. A foam material is delivered into at least a portion of the space to fixedly adhere the fenestration unit to the insulating core of the composite panel. The foam material typically provides the primary structural attachment between the fenestration unit and the composite panel.