How to Build a Fireplace Mantel from Scratch – DIY Home Projects

You can create your own custom homemade fireplace mantel all from scratch. You don’t need to be a carpenter to tackle this DIY project! All you need are the right tools, a little know how, and the right attitude!

You can build your own fireplace mantel in an assortment of styles, themes, and colors.

This article will show you how to build a fireplace mantel from scratch. Remember, you can add your own special touch by altering the design with trim accents to appease your taste. This will give you give you an understanding of the correct steps and structural foundation needed to build your own fireplace shelf. Let’s jump right in!

DIY Fireplace Mantel

Fireplace mantels are decorative surrounds that add style and beauty to the home. They can transform the hearth from basic and flat to stunning and eye-catching. Although they improve the aesthetics of the home dramatically, it’s important to keep in mind that mantels must be functional as well.

When building your own fireplace mantel, make sure that strength and durability are a priority. The fireplace shelf will hold various novelties, picture frames, and other decorative items. Here’s what you’ll need to build your own fireplace mantel.

Supplies for Your Homemade Fireplace Mantel

  • 1×10 Pine Wood Boards
  • Decorative Molding
  • Wood Glue
  • Construction Adhesive (Glue)
  • Sandpaper
  • Paint and/or wood stain
  • Painters Plastic
  • Stud Finder
  • Leveler
  • Pneumatic Brad Nailer & Air Compressor
  • Table Saw
  • Circular Saw
  • Safety Glasses

Step by Step: Building Your Own Mantel from Scratch

Step 1 – Sketching

Begin by sketching your design on a sheet paper. Take measurements of your firebox and work around that. Think of how wide you want your mantel to extend around your fireplace, what colors you would like to use, style of molding/accents, and the depth of the mantel shelf.

If you plan on placing larger items atop your mantel shelf, try a 6” mantel so you have ample space for décor. You can browse through a gallery of fireplace mantels here to get some ideas on how you would like yours to look.

Step 2 – Legs

First we are going to start off with the legs of your mantel. The legs refer to the two columns on either side of the mantel that travel vertically to support the mantel shelf. Legs should extend from the floor to the bottom of the mantel shelf.

Build Your Own Fireplace Mantel Legs

  • Use a circular saw to cross cut (cutting across the grain) pine wood to the length of your mantel columns.
  • Use a table saw to rip the edges of your legs at about 1-1.5” on each side. Make sure that both sides are the identical. The smaller 1” pieces will be used to create a 3 sided box. This will give your columns a 3D look that pops out of the wall instead of just being flat pieces of wood attached to the wall.
  • Make a 3 sided box by using wood glue and a nail gun to attach the ripped board to the two edge pieces.
  • Use a stud finder to nail the mantel columns to the wall.
  • A leveler is necessary to be 100% sure that your mantel is straight. Nothing will irritate you more than staring at a crooked fireplace mantel all winter!
  • Place beads of construction glue along the surface area that will come into contact with the wall to ensure a firm hold.
  • Use a nail gun to attach the mantel legs to the wall. Nail at an angle to “toe nail” the mantel to the wall.

Tip: Remember to sand all pieces of wood before nailing them to the wall. This will create a smooth finish and also help painting in the final steps.

Step 3 – Breast Plate

The breast plate is the middle piece that is located above the firebox, in between the legs, and beneath the mantel shelf.

Fireplace Mantel From Scratch

  • Cut the breast plate to the dimensions of your own custom mantel.
  • When attaching to tile/marble, use construction adhesive since you can’t nail the mantel through tile.
  • Using a nail gun, attach the breast plate to the wall. As in Step 2, make sure you use a stud finder and a leveler for best results.

Step 4 – Attach Molding

Now that we have the skeleton of our homemade mantel set up, we can start adding crown molding to the top of the mantel beginning at the breast plate. You can layer your mantel using multiple molding to fashion an ornate design.

Fireplace Mantel Molding

  • Using a circular saw, cut pieces of crown molding to the required dimensions. Make sure that you make cuts at a 45 degree angle when working with molding or trim. If you don’t, perpendicular corners will not fit together correctly. Your circular saw has a setting that allows you to change the angle of your cut. Review the owner’s manual if you do not know how to use this feature.
  • Use a pneumatic brad nailer and place a bead of wood glue across the contact area of the molding. The pneumatic brad nailer will release needle like nails that prevent splitting and make sure nails are less evident.
  • Attach molding to the breast plate first then follow this with molding on the top of the column legs.

Step 5 – Install Mantel Shelf

Build Fireplace Mantel Shelf

  • Use a circular saw to cut a mantel shelf to sit atop the two columns.
  • Run a bead of construction adhesive along the contact surface of the mantel to create a stronger bond.
  • Use a nail gun to nail the mantel shelf in place.

Step 6 – Decorative Accents

Now for the finishing touch. Add surface molding to accent the mantel. Surface molding creates a beveled face and gets rid of the flat look that your mantel once had. You can add base molding to the feet of the mantel legs to give it an elegant and complete finish from head to toe!

Tip: Remember to cut all trim corners at a 45 degree angle so that perpendicular pieces will fit flush. Do this with all trim accents that will come to a corner.

Step 7 – Painting Your Mantel

Select paint in the color and finish of your choice. Use heat resistant paint to accommodate the high temperatures associated with the hearth.

  • Wrap the surrounding area of your fireplace with painter’s plastic to make sure that you don’t make a mess on the carpet.
  • Use interior grade spackle to fill in nail holes and any small imperfections in the wood.
  • Paint all areas of your fireplace.
  • Let stand for 24 hours or until dry.

DIY Fireplace Mantel Video Demonstration

Building your own fireplace mantel from scratch can be a rewarding project. Not only can you save lots of money, you get to create your own custom design unique to your home! We’ve included this Instructional Video that will go along with the Homemade Mantel Guide we’ve provided above. Make sure you watch it to see how you will apply each of these steps to build your own fireplace mantel!