How to Add a Door to a Cut Concrete Beam

Attach a 2-by-4 frame to the cut concrete beam. Start by building a rectangle on the floor slightly larger than the door that will be inserted. For example, if you are installing a 36-inch door that is 96 inches tall, build a rectangular box that measures 37 inches by 97 inches on the inside of the frame.

Cut one 40-inch treated 2-by-4 and one 37-inch treated 2-by-4. Cut two 97-inch treated 2-by-4s. Assemble the box by placing the two 97-inch 2-by-4s side by side. Place the 40-inch 2-by-4 on the end and attach with 3-inch wood screws. Insert the 37-inch 2-by-4 at the opposite end between the two 97-inch boards rather than on the end. Attach with 3-inch wood screws. You will remove this board later on.

Set the frame against the cut beam with the 27-inch 2-by-4 on the bottom. Attach the frame to the beam with concrete screws. Drill through the frame with a hammer drill fitted with a 6-inch concrete drill bit 1/4 inch in diameter. Space the holes 16 inches apart. Check the frame with a 4-foot level to ensure it is plumb front to back and side to side.

Remove the bottom 2-by-4 from the frame with a reciprocating saw. Cut through the ends of the 27-inch 2-by-4 where it intersects the side lumber, severing the screws. Tap the lumber free with a hammer.

Slide the door and frame in place inside the wooden frame and attach the frame trim at the bottom corner where it overlaps the wooden frame. Shoot 2-inch finish nails through the trim and into the frame with a finish nailer. Place a framing square on the top inside corner of the door and position the door so that it is square. Place a finish nail in the top corner and check that the door opens and closes correctly. Finish nailing the door in place with the finish nailer and replace the trim on the opposite side of the door.