How to Build a Custom Fireplace Mantel

In this video, This Old House general contractor Tom Silva helps a homeowner build a custom fireplace mantel.

Steps for Building a Custom Mantel

1. Spread a canvas drop cloth onto the floor in front of the fireplace.
2. Cut three poplar boards to size to form the vertical pilasters and horizontal frieze of the fireplace mantel.
3. Join the boards together with glue and pocket screws.
4. Rout a rabbet into the back edges of the mantel so that it will overlap the wall tiles that surround the fireplace.
5. Cut a filler strip to fit behind each side of the mantel.
6. Glue and nail the filler strips to the back of the mantel.
7. Rip a narrow strip of poplar to trim out the top of each pilaster.
8. Glue and nail the trim to the mantel.
9. Use the circular saw to rip a poplar board to fit along the top of the mantel. This board will support the crown molding and mantel shelf.
10. Cut a poplar nailer strip and narrow trim piece to fit the length of the mantel, then fasten them to the mantel with glue and pocket screws.
11. Next, bevel-rip a 1×5 board to width to form the crown molding.
12. Cut a 45-degree miter into each end of the 1×5 crown.
13. Miter-cut a short return piece of 1×5 poplar to fit at each end of the crown.
14. Glue and nail the return pieces to the crown.
15. Glue and nail the crown to the nailer installed on the mantel.
16. Stand the mantel against the fireplace wall and secure it to the wall studs with 3-inch screws.
17. Cut a poplar shelf to fit across the top of the mantel, then nail the shelf to the nailer strip. Also nail at an angle up through the crown molding and into the underside of the mantel shelf.
18. Fill the nail and screw holes with wood putty. Allow the putty to dry overnight, then sand lightly with 120-grit sandpaper.
19. Finish by priming and painting the mantel.

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