How to Fit a Salvaged Door in an Existing Opening

In this video, Ask This Old House general contractor Tom Silva takes a homeowner’s salvaged door and uses several tricks to make it fit.

Steps:
1. Remove the hinges from the doorframe using a driver in reverse or a screwdriver.
2. Remove the hinges from the door using a driver in reverse or a screwdriver.
3. Place door in opening and push it up tight to the header.
4. Use a pair of scribes to follow the angle of the gap between the header and the door, starting at the widest gap and tracing until you reach the lowest gap.
5. Cut the marked portion of the door using a track saw.
6. Take a small piece of wood and line it up with the top hinge. Mark it ⅛ inch longer than the door to account for the space between the header and the door.
7. Also mark the distance on the wood from the edge of the hinge to the face of the door. Now, that can serve as a gauge for making the hinge points in the doorframe.
8. Place the gauge tight against the underside of the doorframe. Using it as a guide, match up the hinge with the edge on the gauge. That’s where you want the hinge to be placed.
9. Drill holes through the holes in the hinge and drive in screws.
10. Mount the bottom hinge by using the same reference lines on the gauge.
11. Close the door and see how it fits into the opening.
12. If there is a gap between the door and the frame on the hinge side, you may have to mortise out the hinges.
13. Next, check the distance between the door and the floor. If there’s a gap, you may have to account for it by adding a piece.
14. Measure the distance between the door and the floor at its highest point. Take that measurement and subtract ⅛ inch; that’s what you’ll want for the added length.
15. To add the extra piece of door, take the measured piece of poplar and glue it to the bottom using wood glue.
16. Then drive in two screws at the bottom to keep the poplar and the door together.
17. Using a hand plane, plane the piece of poplar until it’s level with the rest of the door.
18. To create a fake seam to match the rail of the door, use a rafter square as a straight edge and a utility knife to mark the poplar. Go over the cut several times.