How to Install an Exterior Fire-Rated Door

Measure the doorway opening and compare it to the size of the exterior fire-rated door. Remove portions of the doorway, if needed, with a reciprocating saw. File down sections that only require slight adjustment. Try to wedge the door frame in place and adjust the doorway, as necessary, until the frame fits. Remove the door frame and apply a thick layer of caulking all the way around it. Reposition the door frame in place and remove all excess caulking with a putty knife.

Use a carpenter's level against the sides of the door frame with the door open to determine if the frame needs to be adjusted. Open and close the door repeatedly to see if the motion is impacted by the frame's position. Set shims around the frame if necessary and hammer them in place to level the frame. Break off any excess shims that stick out from the door frame.

Drill holes into the center of the frame and into the doorway, spacing the holes every 12 inches around the frame with the door open. Set 3-inch galvanized wood screws into each hole and tighten them down completely to attach the door firmly in its level position.

Position the trim boards, if necessary, against the interior and exterior of the door frame. Drill out any attachment holes and attach the trim with 3-inch galvanized screws.