Abstract: A process for insulating a register box in which the register box has a plurality of side panels arranged in a generally rectangular configuration and a duct opening through a wall that extends across the generally rectangular configuration, in which the process includes flowing an expandable polymeric material toward the plurality of side panels, placing the register box into or onto a support structure, introducing a liner over the flowed expandable polymeric material within the register box, and placing a form onto the liner in the register box so as to shape the expandable polymeric material within the register box. The form and the liner are then removed from the register box.

Abstract: A register box for HVAC installations has a body with a plurality of side panels arranged in a generally rectangular or square configuration and a wall extending across the rectangular configuration, a duct opening through the wall so as to communicate with an interior of the body, and an expandable foam polymeric material affixed to an inner side of the side panels. The wall has a surface extending from the opening of the duct to the side panels. The expandable foam polymeric material is affixed to the surface of the wall. The expandable polymeric material is polyurethane.