How to Build a Fireplace Mantel in 5 Steps

October 7, 2020 admin 0 Comments Home

Though there’s no shortage of pre-made mantels on the market, we’re builders at heart, so we set out build a DIY fireplace mantel from off-the-shelf lumber. We opted for a traditional-looking design that goes with many types of decor.

What Is the Best Wood to Make a Fireplace Mantel?

Made of ¾-inch veneer plywood, our mantel is layered with elegant pilasters that are wrapped with stock moldings and baseboard, and topped with a trimmed-out shelf.

As with any fireplace project, safety is paramount. National codes require at least 6 inches of clearance all around the firebox and an additional 1 inch for every ⅛ inch a mantel protrudes from the surface; local codes might be stricter. So tailor your design or pick your product accordingly. A cardboard template can help you determine whether a mantel is the right size and scale for your space. Install one soon, and you’ll love how it frames your favorite gathering spot.

How to Build a Fireplace Mantel in 5 Steps

Step 1

Measure Your Space

Size the mantel to fit your fireplace, and choose moldings and trim that mimic nearby profiles

Step 2

Cut the Pieces

Illustration of the fireplace mantel pieces.

Cut the shelf, breast, legs, returns, and nailing strips to size.

Step 3

Assemble the Mantel

Illustration of the wood mantel assembly.

Attach the legs to the breast by screwing plywood cleats across their back seams. Screw nailing strips to the back of the assembly, ¾ inch from each outer edge. Set returns against the strips, flush with the outer edges. Secure them with screws.

Step 4

Cut and Add the Trim

Illustration of the fireplace mantel trim.

Nail centered pilasters to each leg. Install a nailing block on each pilaster flush with its top edge. Miter and nail trim to the mantel according to the diagram below. Start with baseboard at the bottom, add crown molding at the top, then add astragal molding below the crown molding and along the bottom of the breast. Miter and nail the doorstop to the mantel’s interior edges to finish the return to the surround.

Step 5

Attach the Shelf

Trim the shelf by mitering and nailing shoe molding to its edges. Nail through the top of the shelf into the mantel. Fill all fastener holes before sanding and finishing the entire piece.