How to Make a Floating Mantel Shelf

I recently moved and decided I wanted to improve the look of the living room, specifically the fireplace area. So I gathered up some old 1x6 and 1x8 pine wood, and I was able to improve the look of this old plain fireplace by building a solid block mantle. And I'm going to show you step by step on how I did it. Let's go! I started this project by assembling my Husky portable workbench, which is fantastic by the way, and I'll have it linked below. I then got three pieces of the 1x8 pine wood and cut them down to 48 inches, which is the width of my fireplace. So again, cut three 1x8 pine wood pieces to 48 inches, or to the width of your fireplace. After cutting the three boards, you can set them aside. Next, I grabbed a scrap 1x6 piece, then cut it down to 36 inches, because it's going to be used as a smaller French cleat support brace. I'll go into more detail later. Next, I measured and cut two 7 1⁄4 square pieces. The reason I cut this to 7 1⁄4 is because in America, a 1x8 measures in at 7 1⁄4. It's weird, but just cut a square the width of your board. I then used this AccuMaster digital square to angle my table saw to 45 degrees. To get it precise, adjust the rotary gauge, then lock it in place. I then adjusted the rip fence so that I could make a 45 degree miter cut. I then made the miter cut on all four sides of both squares. These miter squares will be used as the end pieces for the mantle. These pieces won't actually go together, but I want to show you how a mitered cut works. The 45 degree cut makes it joint very tightly, which will then make it look like a solid piece of wood. The next step is to miter the three pieces we cut earlier, but note that we only cut one side for two of the boards. The single mitered boards will be the top and bottom of the mantle. The board with two mitered cuts will be the front of the mantle. Again, only one board will have two mitered cuts. To make the mitered cuts, we pass the board through only on the length of the wood. We'll cut the ends later with a miter saw. Once the length of the boards have been cut, adjust the miter saw to 45 degrees. We're going to miter these edges so that they'll fit the end caps. I'm going to cut both ends so it'll be a total of six cuts. To give you a better idea of what we're trying to do, I'm going to place the boards with a single mitered cut on the outside, and these will be the top and bottom of the mantle. You can see that because we made a mitered cut, they fit very well together and will look like one solid block of wood. I mitered the square piece earlier so that it will sit flush on the end. I did all four sides so I can rotate it if one side fits better than another. Now that we're done cutting the boards for the outside, we can stack them up and set them aside. The next step is to grab the smaller 36 inch piece, then we're going to make a mitered cut down the middle so we can use it as a French cleat bracket. You can just estimate the middle of the board and make the cut, but I'm going to teach you the formula if you want to make a mitered cut exactly down the middle. First step, measure the board, which is five and a half inches. Second step is to take that number and divide it in half, which comes out to be two and three quarters. Third step is to take the thickness of the board, which is three fourths, and divide that number in half, which comes out to be three eighths. Fourth step is to take half of the thickness of the board, which is three eighths, and subtract that from half the width of the board, which is two seven five. The final number will be two and three eighths, which is where we'll make our cut. So half the width minus half the thickness comes out to be two and three eighths. You also need to account for the thickness of your saw blade, so sometimes it's easier to skip all the math and just estimate it. The reason we mitered this down the middle is so that it will act as a French cleat. A French cleat works by facing the angled cut away from the wall. A top angled cut will rest on top of the cleat, allowing it to fit perfectly in place, and it can also support a lot of weight. Now I need to attach the French cleat to the underside of the top of the mantle. Make sure you're putting it on the flush side, not the mitered side. For this part, I grab some clamps, some glue, and a square. I'll also use an 18 gauge nail gun. I then place some wood glue on the underside and smooth it out. The glue can dry fairly quickly, so make sure to have a cleaning rag and the clamps ready. Use very little pressure on the clamp so you don't break the cleat. Then use the square to make sure it's level. Once it's set, use your nail gun to secure it in place. I then waited about an hour for the glue to set. Once the glue is dry, the next step is to put the rest of the mantle together. Again, for reference, the cleat we just installed is the underside of the top of the mantle. To secure the other pieces, I used some painter's tape to help hold them down while the glue dried. Make sure when you're placing it that you align the end pieces very tightly together. If there's a gap on the end, it will definitely stand out. Make sure to use a generous dose of glue, and then we can put it together. When you're ready to put it together, you don't have to use this painter's tape. It's only there to help hold it until you can nail it down. I'm done with the top of the mantle, so I repeated the same steps for the bottom side. I let it sit for a while for the glue to dry, then took off the tape and put some more nails in it. With the outer shell done, I was ready to put on the end caps. Earlier, I made a mitered cut on all four sides so that I could rotate it to find the best fit. Once there, I flipped it over and put glue all around the outside, then nailed it in place. I got a little trigger happy, but I made sure this thing wasn't going anywhere. I then repeated the same process for the other side. The assembly of the mantle is now finished, so now we just have to make it look nice. Because the mitered edges are very sharp, I took the round side of a screwdriver and softened it down. This also really helps it look like a single block of wood. Now, I wanted to go with a really weathered look, so I got some random tools around the shop and gave it a good beating. It was all trial and error to see what worked, but I found that making tiny holes or single line cuts like this made it look like natural wormholes in the wood, and it looked really nice when I stained it. Make sure you don't beat up the cleat, or else it could break off. It will also be covered up, so it doesn't need to be prepped. Once that was done, I decided I wanted to better secure the cleat to the wood, so I measured out three marks to drop some screws. I went with the 3-8 Forstner bit to hide the screw heads and make it look flush. A Forstner bit makes a larger hole in the wood, which I can then place the screw inside. With the screws in, I then used some 3-8 wood plugs to fill in the hole. These plugs match the 3-8 drill bit and are cut at an angle to sit firmly inside the hole. To fit it in place, put a drop of wood glue, then use a rubber mallet to tamp it down. I then sanded everything down to make it smooth. I used a rag to wipe off all the dust and check for splinters. I'm really happy I used the Forstner bit and wood plugs because everything now sits flush. I especially like that I made the single line cuts, as they look like naturally formed wormholes. With the wood now sanded and cleaned, I decided to stain it with a Behr brand Jacobean color. This is a water-based stain, so it's going to have low odor, and I'll need to make sure my sealant is also water-based compatible. This was a dark enough stain, so I only used one coat. As a rule of thumb, always apply a very light first coat, because you can always add more later. Once you've put it on, it's almost impossible to make it lighter. Also make sure the wood is very clean and free of dust, and use a lint-free rag when applying stain. When the stain was dry, I went back and applied two layers of polyurethane. I used a water-based stain earlier, so I made sure that this was a water-based polyurethane. When you first apply it, it goes on white, but it will dry clear. Again, apply a light layer and add more later if needed. Also don't touch it, or else it seals the fingerprints. I applied a second coat and let it dry overnight, and when I came back the next day, I thought it looked fantastic. With the stain done and sealed, I was now ready to hang it up. To hang it up, I'm going to take the other half of the cleat, and secure it so it angles towards the wall. You don't need to screw the mantle to the bottom piece, because it will use its own weight to hold itself down, and the angled cut will keep it against the wall. Next step is to go inside and hang up the mantle. To put the cleat in the right place, I measured from the bottom of the mantle to where I made the cut for the cleat, which was about 4 inches. I then located all the studs and marked everything out. Once everything was marked out, I grabbed some 3 inch construction screws, then used a level to make sure the cleat was set correctly. I then pre-drilled some holes so the screws would go in much easier. With some help from a lovely assistant, I double-checked that everything was level, then screwed it down. Everything was set, so I was ready to put on the mantle. As you'll see, another bonus of using a French cleat is that it's so easy to hang things. All I had to do was lift up the mantle, and then just set it down on top of it. And with that, the mantle is secured to the wall. And this project is pretty much done. I think it turned out great, and it really does look like that heavy block of wood fill that I was going for. It really improved the entire look of the room. I will note because the French cleat is so strong, there was no problem setting heavy decorations on top. I really enjoyed this project, and hopefully it helps you build your own mantle. If you want some other home projects that you can do, check out my other videos linked below. Thanks so much for watching and sharing this video, and have a great day.