We updated the family room during the summer of 2019. Part of that remodel was replacing the old dated pine mantel with an updated oak one. This is how I built it.
I drew up several possibilities for mantels in Sketchup for Johanne and Gina to review. We discussed several possibilities in style, wood, color and finishes. We ultimately decided on oak, stained black, with a matte polyurethane. (11/2019)
I started off with a partial pine mock-up to get a sense of the scale and to get buy in from the ladies. (11/13/19)
Rather than buying a thick board for the top of the mantel I added a band around the top. I cut the edge of the top board off and flipped it underneath to book-match the grain. I also kept the end grain on the ends, also book-matched, to continue to look of a single board. (11/11/19)
Here is the glue-up of the edge. There is no such thing at too many clamps. Its not visible in this picture, but I had to use some of my 3' clamps to make sure I had enough to go all the way around. (11/11/19)
I used a longer vertical board so the grain is continuous around both corners (forgot to take a picture of that). Unfortunately, I came up a little short on one end. Fortunately this is the edge near the corner of the room so it won't be seen (11/11/19)
The design includes a bevel underneath the top board. The size of the bevel calls for a large bit (the biggest in my collection as of this writing). I make a jig to extend the base down to the top of the board since there is a small surface on which to rest the router. The circle is the same thickness as the glued on edge. The short board on the other side is there to stiffen the jig. (11/13/19)
Here I'm adding the bevel to the underside of the top. I had to slow the router down due to the size of the bit, and took several passes with a very light final pass to avoid burning. (11/13/19)
I'm preparing the vertical board for installation by drilling a series of pocket holes. I could probably get away with just glue, but I tend to over-build so I added them in. I added biscuits for the miters partially to add some strength but mostly to ensure alignment when screwing the parts to the top. (11/13/19)
The vertical boards are glued and screwed to the top. Not so many clamps this time since the (a) the boards are thicker so the clamps can be spaced further apart and (b) the screws serve as permanent clamps. (11/13/19)
Here is another view of the mantel from the front. I think I accomplished my goal of making it look like a thick board for the top. (11/13/19)
I don't have a good way to cut a clean edge at the ends of the boards so I set up some plywood with a cleat on the end and used a router with a flush trim bit to get a smooth edge. (11/17/19)
In my zeal to get the vertical board attached to the top, I neglected to put screw pockets on the other side to attached the bottom. I added an additional support board with screw holes on both sides to secure the to and bottom boards together. There was a slight bow in the boards, so adding the extra board is probably useful anyway. (11/17/19)
Here the top and bottom are glued together. (11/19/19)
Another look at the final glue-up. (11/19/19)
Installing the vertical board onto the top was easy with a standard drill and a long square drive bit. It's too tight for that inside once the bottom is attached. I used a right-angle attachment on my drill to drive the screws most of the way, but didn't work for final tightening. I used a small wrench on a square bit to drive the screws home. (11/20/19)
I built a cleat to mount the mantel to the bricks. I added short arms for additional support. The top and bottom of the mantel were curving towards together a little bit in the middle so I added an additional support there. I beveled the edges of the cleat (not seen here) to make sliding the mantel on the cleat easier. (11/20/19)
I used three coats of stain to make sure I got it as dark as possible. It looks a little splotchy here because parts are still a little wet. I also stained the edges of the wall cleat in case they are visible from the side through the mortal lines after the mantel is mounted (they weren't). (11/21/19)
We use a matte water-based (technically waterborne) polyurethane. It looks a little blotchy here because its partially wet. The water-based poly dries quickly and clear. I sanded after the second coat to make sure the final coat was as smooth as possible. (11/21/19)
Here the cleat is mounted to the bricks. I initially screwed Tapcon screws into the mortar joints, but that didn't work very well. After some research I found many posts that said never mount to the mortar. I moved the Tapcons to new holes drilled through the bricks. Since I had already drilled the other holes in the mortar I used wedge anchors in those holes for additional strength. (11/27/19)
Here the mantel is mounted to the fireplace. I used a few trim screws through the top of the mantel down into the cleat to prevent it from sliding off. They didn't need to be particularly big or strong since the weight is supported by the screws in the wall and the arms on the cleat. (11/28/19)