How I Built a Custom Fireplace Mantel to Match My Client’s Staircase

By / May 12, 2018
Home » How I Create Art - The Build Process » How I Built a Custom Fireplace Mantel to Match My Client’s Staircase

After finishing up my last project, a custom staircase and handrail, the customer asked me back to design and build a fireplace mantel for them.

Here are some of the specialty tools I used on this build. (affiliate links)

If you caught my last project, you saw me build a custom staircase and handrail. Well, my client loved the newel post design so much that they asked me to build a fireplace mantel in the same style. Challenge accepted!

Milling the Stock

I started by ripping the stiles roughly to width, along with the sides of the mantel and the inner panels. Then I sent everything through the planer to get them to the various thicknesses I needed for the project.

The Miter Strategy: Making It Look Seamless

Here’s where things get interesting. I decided to miter the sides of the mantel to the front stiles, but I didn’t want it to look like a miter joint. Before rough cutting these pieces, I spent some quality time studying my boards, selecting parts with similar grain patterns and coloring. When done right, the mitered corners would look like one continuous piece of wood—unless you really inspect it closely, you’d never know they were mitered together.

When I ripped those long miters, I set up a featherboard to keep the stock tight against the fence. This little trick helps ensure the miter closes up nicely with minimal fussing along the entire length.

The Tape Hinge Trick

For the glue-up, I used my favorite technique: blue tape as a hinge. I taped the parts together so I could fold them into place after spreading the glue. Pro tip: don’t tape the full length. I left spaces every few inches so I could see the miter point and make sure it was staying in place and closing up tight.

Once I spread the glue and folded everything up, I added more tape to hold it all in place while the glue dried. Simple, effective, and no clamps required for this step!

Trimming to Final Dimensions

When I originally cut the mitered stock, I intentionally left it a little long—you know, just in case one got out of square or I messed up the miter somehow. Insurance, basically. Now that the components were assembled, I ripped the stile to its final width along with the sides of the mantel.

I’d also left them long so I could slide the parts back and forth during glue-up to match the grain as closely as possible. Now it was time to square one end on each piece, then set up a stop block to ensure they’d all end up the same length.

Assembling the Legs

All that was left for the main leg structure was cutting the rails to width and length and assembling them to the stiles.

For joinery, I used the smallest domino I could find. Don’t have a domino? No problem! You could absolutely use a biscuit joiner for this, or even cut mortise and tenon joints. Fair warning though—the stock is only about 3/8″ thick for the reveal, so you’d be cutting some pretty tiny mortise and tenons.

To make working with these long, skinny pieces less awkward, I clamped them in my vise while cutting the mortises. For the small rail pieces, I used one against the back of the other to add stability—safety first!

Since I was gluing end grain to long grain, I made sure to spread glue on both the domino and in the mortise. This isn’t the place to skimp on glue if you want joints that won’t fail.

Building the Header

The header piece followed much the same process as the sides. I jointed a straight edge to run against the table saw fence, then ripped a miter down the side. The glue-up was identical to before—just some blue tape to hold the miter together while it dried.

I added plywood cleats to the legs to give me something solid to nail the header to later.

Then I did a mock-up so I could take exact measurements for a filler strip that the cove molding would attach to. I didn’t shoot video of making that filler strip, but you’ll see it installed later. Basically, it was a 3-inch board with mitered returns on the ends leading back to the wall.

Creating the Cove Molding

Time to make the cove! I started by routing the profile on the tip of a board. Then at the table saw, I set up a dado blade to remove the bulk of the material. This reduces the load on the router and honestly saves time in the long run. It also reduces the chance of blowing out a big chunk of wood while routing. I did a horizontal pass and a vertical pass to remove most of the waste.

Here’s a tip: lighter passes at the router typically produce cleaner cuts. And since it’s safer to rout a bigger piece (less chatter) than a small one, I used a wider board than I needed and routed a profile on each side. Then I went back to the table saw and cut the cove free.

I switched out the router bit to a roundover and used the same process to cut some quarter round for the base of the legs. Just be sure to have your push stick ready!

The Top Shelf

The shelf was the final piece I needed to make before staining and installing. I used the same nosing bit as I’d used on the staircase to create the bullnose edge.

I started by cutting the profile on the end of a board to help me find the right blade angle to remove the bulk of the material—same strategy as before. Then it was just a matter of ripping off the excess and routing the profile.

The final step was mitering the nosing and installing it around the shelf.

Installation Day

Out at the jobsite, my plan was to attach those plywood cleats to the wall first, giving me something solid to nail the legs to. I positioned them inside the legs to figure out exactly where they needed to go on the wall.

I’d left the inner panels out of the legs so I could reach through with my drill to mark the exact location and drill holes for some mollies to attach the cleats to the wall. Smart move, if I do say so myself.

Once the cleats were attached to the wall, I pulled the legs off and attached the inner panels by nailing them from inside the leg. Then I put the legs back on the cleats, but before nailing them in place, I installed the header to make sure I had a tight fit between the legs and header. Always good to check your fit before committing!

Next came the filler strip—this piece just creates a little reveal and gives the cove molding something to attach to.

Then I positioned the top shelf and took a few minutes to make sure it was perfectly centered. I attached it by nailing from the bottom to hide as many nail holes as possible.

The Final Details

Now I was down to the final trim. I started on one end and worked my way across, installing the cove. For all the final trim work, I used my headless pin nailer. No holes to putty? Yes, please!

Then I added the final detail on the legs, and that was it.

The Finished Product

Here’s the finished mantel—a nice, clean design that goes perfectly with the staircase newel posts. My client was thrilled, and honestly, I’m pretty proud of how those mitered corners turned out. You really can’t tell where one board ends and another begins.

Sometimes taking the extra time on grain matching and setup makes all the difference in creating something that looks truly custom and high-end.

I’m the owner of Benham Design Concepts, a mixed media art studio where I design and build custom furniture and other works of art using wood, glass, stone, and various metals.
In this blog, I talk about the art I create, my journey, and the things I learn along the way.

Scroll to Top