How to Build a Floating Wood Mantel for your Fireplace
Updated: Jun 30
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My dream for our new house was to build a fireplace before Christmas, and I was so excited when that DIY dream came true. Check out that blog here. But once that was completed I had to build a mantel. I had built floating shelves before, so I took that knowledge and just changed the dimensions to create a mantel. This tutorial could also be followed to make a floating shelf, you would just make the dimensions different as desired.
Here’s what you'll need:
Stain (see step 9)
For a video walkthrough of this project, check out my Instagram highlight here.
Build the Support System
1. Start by cutting a 2x4 to the length you want for the mantel, minus how thick the wood for the mantel would be on each side. I used 3/4 inch pine boards, and there would be a board on each side, so the total length I wanted, X, minus 3/4 x 2 = 1.5. I cut the 2x4 to XXX inches long.
2. Next, cut the support arms. I wanted the mantel to be X inches deep, so I cut the arms to X inches, as I had to subtract 3/4 inch for the thickness of the wood for the mantel, and subtract 1.5 inches for the thickness of the 2x4 we just cut, which these arms will attach to.
3. Attach these arms to the longer 2x4 piece. I drilled pocket holes using my Kreg jig. Then I paced them out along the 2x4 and screwed them into place. I also added a little wood glue for good measure. That’s it for the support!
Build the Mantel Box
NOTE: For this build I am using butt joints for all the wood pieces. For a more advanced build, you could cut all your edges on a 45 degree miter.
4. Cut 2 pieces of pine board to the length and width you want for the mantel. When deciding on these dimensions, you will need to take into account the thickness of the wood for the front piece and the side pieces, as these will be included in the overall dimensions. Therefore, if you want the overall depth of the mantel to be 5 inches, the front piece is 3/4 inches thick, so you will cut your top and bottom boards to 4 1/4 inch wide. You can buy pine boards in different widths depending on the size you want to go with. I wanted mine to be X inches deep, so I bought 1x XXX boards that were 8 ft long, and used my table saw and miter saw to cut them to size. If you want to avoid using a table saw, you could make your mantel depth the same as the standard wood sizes, so you would only need to cut them to length, which you could do on your miter saw, or have them cut them at the store.
5. Next, cut the piece for the front, this will be the same length as the two pieces from the previous step, but it can be a different width, depending on how tall you want the mantel to be. This does need to be at least 5 inches wide, to account for the 2x4 from step 1 which is 3.5 inches and the 3/4 inch thickness of the top and bottom pine boards that this front piece will be covering the edges of.
6. Now you need to cut the wood for the sides. These will be the same width as your pieces from step 4, and the same height as your piece from step 5.
7. Assemble these 5 pieces of wood using wood glue, clamps, and a brad nailer with 1.5 inch nails. Once assembled, test fit the support from step one by sliding it into the mantel backwards to make it easier to pull out.
Wood Fill and Sand
8. Apply wood filler to all the seams and nail holes. Over fill slightly, then once dry come back with 220 grit sand paper and sand it down smooth.
Choose Your Stain
9. I highly recommend using a wood conditioner before staining. This helps the stain to apply evenly and prevent blotchy areas. Apply the conditioner per the instructions on the can. I use a cloth rag to apply the conditioner and the stain. I chose to go with a custom stain combination, this is what I did:
NOTE: The first two products I used are water based while the second two are oil based. Typically you would want to stick to one or the other, however, I was using what I had on hand and all turned out well.
10. Attach the support from step one to the fireplace. Make sure to place it at the height you want and to account for the thickness of the wood of the mantel when deciding on placement.
11. Pre-drill holes into the 2x4 to avoid splitting, then screw the 2x4 to the fireplace, making sure to screw into the studs.
12. Slide the mantel onto the support. Once placed where you want it, use screws to attach the mantel to the 2x4 from the top or bottom. You can cover these with wood filler if they are in a spot that is noticeable.
And there you have your floating wood mantel! Decorate as desired, and make sure to tag me on Instagram @handtreatedhome if you make one!
Questions? Email me at firstname.lastname@example.org or feel free to leave any questions or comments below!