How To Build Fireplace Mantels

Building a custom fireplace mantel is a great way to add character to your fireplace. Since you are building on yourself, you can be assured it will be unique and everything you want in it. This isn’t the easiest project, so you will want to practice first. It’s a project that someone with some DIY experience can complete in a day. If this is a first time project for you it may take a weekend. Either way, it doesn’t take a long time, and can be much cheaper than purchasing a pre-made mantel. Here’s what you need to build your own fireplace mantel.

Materials and Tools Required

-Measuring Tape
-Miter Saw
-Crown Molding
-Nail Gun
-Wood Glue
-Table Saw
-Paint To Finish


You want to start by designing your mantel. This is best to do with a sketchbook and pencils. Make sure after you have the initial design that you scale it out with dimensions. This will allow you to determine how much material you will need.


You want to measure around the fireplace, and mark where you plan on having the mantel placed. You will need to add ¾ of an inch to your measurements. This will allow for the extra thickness in the boards used. Make sure you are using a level when you are placing your marks around the fireplace,


The cleat backings need to be cut for support legs. The legs are made by using three boards to form a box on the wall.

Cut the Wall Pieces

The next step is to cut both side and front pieces of each leg. Secure by gluing and nailing together by securing the sides to the back cleats. You also want to attach the front to all the sides.

Cut cleats horizontally along the top for the mantel. Nail this to the wall.

Cut Strips

Cut your furning strips to the height of the mantel. Secure the strips vertically to the wall.

You also want to measure for the front of the mantel face. Cut what you need and nail this to the strips. Use a level to avoid problems later.

Crown Molding

The crown molding gives the mantel a more decorative look. You will need to mark out the lines for the bottom of the mantel where you will place the molding. This is what will form the front piece of the mantel. Secure several pieces of crown molding with the nails. You need this to form layers to build the height of the mantel. You can use your miter joint for the corners. Install the crown molding around the sides of the legs as well.

Top and Shelf

Measure out and start cutting for the top of the mantel. Do this for the shelf as well. Nail this to the cleats you placed earlier.


You can finish out the edges with a router. This is where your creativity and skill will come in to play. You can now finish the mantel, or paint it however you wish.

That’s it. Once the paint has dried you are ready to use your decorative fireplace.