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  • Writer's pictureMatt Weber

Build a Faux Beam Mantle Shelf

Mantle shelves can be installed so they appear to float in place on a wall. This requires internal hardware hidden behind the shelf which fastens to the wall studs. Depending on the weight of the shelves, they can be installed using several different methods.

The popular rustic-style mantle shelves are often made of a solid timber beam or a live-edge slab. They feature the natural distinction and one-of-a-kind character of solid wood, but they can be extremely heavy and often require professional installation.

As an alternative, a DIY woodworker with a table saw might consider building a faux beam to simplify installation. The hollow nature of a faux beam retains the look of the wood but reduces the weight of the shelf, so it doesn’t necessitate heavy-duty hardware such as solid metal rods, which the solid beams require. By using a wooden mounting bracket, you can hang a hollow shelf without requiring the pro-grade tools, precision drilling, or expensive metal brackets associated with installing a solid mantle. And to top it off, purchasing a few 1x and 2x pine boards is typically less expensive than purchasing a hardwood slab or timber beam from a lumber supplier.

The Hollow Shelf of the Faux Beam

The faux beam shelf is essentially a hollow box constructed of a 3/4-in. boards. The adjoining edges are cut at 45-degree bevels on the table saw so the form square 90-degree box corners. The rear wall of the box is left open to slip over the interior mounting bracket. The example shelf shown in the photos is made from pine because the softwood lumber is easy to dent and ding for a distressed appearance, but if you want a more refined finish, then consider a hardwood species.

Decide the dimensions of your shelf and purchase materials accordingly, with the understanding that this design requires a shelf at least 3-1/2 inches thick to house the internal mounting bracket. The interior bracket should be built long enough to bridge at least two studs (usually 16” on-center) for mounting the screws into solid wood. This means the hollow shelf should be built a minimum of 22 inches long to house the bracket.

Common dimensions for this type of shelf are 4x8, 4x10 and 6x10. First step is to cut all the 3/4-in. boards to their final length, then use the table saw to rip 45-degree bevels along all the mating edges.

To begin assembly, lay three or four parallel strips of painter’s tape on a flat, sturdy work surface. Arrange the three shelf boards edge-to-edge lengthwise at right angles across the tape in preparation to fold them together. Lay the narrowest board between the two wider boards that will comprise the top and bottom panels of the shelf box. Press the tape in place for a better bond to the wood.

The beveled joints comprise the edges of the box, and it’s a good idea to use a marker to color the inside edges the same tone as the stain you plan to apply to the outside of the shelf. This will help disguise the assembled edges to look like solid wood.

Apply a liberal amount of wood glue to the beveled board edges to strengthen all the wood joints. Use a reliable, high-quality adhesive like Titebond III.

Before folding the shelves together for assembly, insert a couple of wood blocks to help support the inside of the boards and maintain the box shape. Carefully fold the three boards together over the blocks. Some separation will happen along the seams, but wood clamps can help keep the seams together and hold the box square. Once the seams are aligned, carefully drive 2-in. brad nails through the right-angle edge joints, spacing them about 6 inches apart. Drive the brads through the top and bottom panels into the narrow board, then drive brads through the center board into the larger panels.

The end panels are cut with bevels to fit inside the hollows at the ends of the box. Glue and nail each beveled end panel into place.

After the glue has dried, finish the exterior of the shelf for your desired appearance.

Wood In Distress

Giving a distressed texture to the shelf not only imparts an interesting weathered and aged appearance to the wood, but it makes it easier to close the seams and achieve the convincing look of a solid wood beam. We use a variety of tools—from hex nuts and tow chains to drill-mounted flap wheels—to apply lots of dents, dings and relief to the shelf surface, all of which will absorb wood stain at different rates for interesting visual contrast.

Since we’re unconcerned about having perfect edges on a shelf of this style, we hammer or round off the edges with a blunt instrument, which closes the seams at the edge to look like uninterrupted wood grain. Treat all visible edges in this fashion to create the look of an aged beam of timber.

Pro Tip: Any small gaps or open seams at the joints can be sealed with wood filler before staining, but the filler absorbs stain at a different rate than the surrounding wood, which can create a mismatch in color. For this reason, it’s a good idea to use a wood filler tinted closely to the color of stain you plan to apply to the shelf.

Interior Bracket

The internal bracket that supports the hollow shelf is a ladder-shaped structure that will be anchored to the wall studs using 5- or 6-in. structural screws. For a 4x8 or 4x10 shelf, the bracket is made from 2x2 material. For a 6x10 shelf, a similar bracket can be built from 2x4 boards.

The number of cross-members will depend on the shelf’s length. For short shelves, one

center cross-member will suffice. Note: If you know where you’ll hang the shelf, you can

mark the wall studs and locate the bracket’s cross-members accordingly so you can easily screw into the studs without obstruction. The photos in this article will show the basics of bracket construction.

Second to the bracket’s hold against the wall, its most important connections are the joints between the bracket’s back rail and its cross-members. To provide a strong hold, we recommend cutting half-lap joints at the ends of the rail. The two end members connect onto the rail with mating half-laps. The half-lap joints provide increased surface area to apply wood glue and are fastened with countersunk cross-grain screws from the top and side, which is substantially stronger than driving screws into the end-grain of a board.

You can cut the half-lap joints using a band saw, a table saw equipped with a dado set, or use a router table outfitted with a straight bit.

In a pinch, you can even make the cuts with a multi-tool or jigsaw, if the boards are securely clamped to a workbench.

When adding any internal cross-members between the end pieces, we recommend driving structural screws through the back rail and down the length of the boards. Apply high-quality wood glue at all joints.

The outer rail doesn’t carry as much load, so it can be screwed through the front rail, completing a ladder-shaped bracket with all board joints flush at the top and bottom. (The front rail may be attached after the rest of the bracket has been mounted to the wall.)

Bracket for longer shelves include more cross-members.

To build a bracket for a larger 6x10 mantle box, use the same techniques to build a bracket made of 2x4 lumber.

Installing the Mounting Bracket

First, decide your preferred location and height of the Faux Beam Shelf. Mark its top mid-point exactly where you want it mounted on the wall. Tip: We recommend making pencil marks over masking tape to avoid blemishing the wall.

Use a stud finder to locate and mark the wall studs at the installation area near the top height of the shelf.

Mark the mid-point of the shelf on top of the bracket. Align the bracket’s mid-point 3/4” below the shelf mid-point you marked on the wall. Mark the stud locations on the bracket.

On your workbench, drill pilot holes in the bracket for the mounting screws as close to 90-degrees to the wall as possible. If your screws have self-starting tips, you can skip the pilot holes. (Note for DIY'ers: It will probably be easiest to drill the mounting holes with the front rail detached from the bracket. You can reattach the front rail after the bracket has been mounted to the wall. Otherwise you'll need a long bit extension, as shown in the photos,)

Return the bracket to the wall, aligning the midpoint marks, then use a bubble level to make sure it is level.

Once the bracket is in position, drive 6” cap-head structural screws through its back and into each wall stud it crosses. (The HIR staff uses Construction Screws from U2 Fasteners.)

This installation method requires a minimum of two stud connections. Tip: Once you’ve marked the stud locations on your bracket, you might find it easier to start driving the screws while it is on your workbench, then finish driving them into the studs once the bracket is in place against the wall.

Drive the mounting screws tightly to ensure stability of the bracket and to arrest any wobble or movement.

Install the Shelf

Slide the hollow Faux Beam Shelf over the bracket. Center its position, then fasten it

by driving trim-head screws through the top board at the very rear of the shelf, sinking

them into the back of the interior bracket. Strengthen the installation by driving additional screws into the bracket from the bottom of the beam.

The tiny heads of the trim screws will sit hidden just below the woodgrain surface and blend with the look of a rustic-style shelf.


"Tree Rings" on your Shelf Ends

You may have noticed a circular woodgrain pattern on the ends of our floating shelves.

At our carpentry business, Rustic Shelves & Shutters, we modified an orbital sander using a disc outfitted with protruding screw tips. We clamp a jig over our 3/4” shelf boards, which holds this tool in place as we use it to carve the circular groove pattern. We then cut our shelves’ end panels from the circlegrooved boards. Once stained, the circular pattern helps complete the illusion of tree rings, which gives the shelf a more authentic log-like look.

Although DIY’ers probably won’t be modifying a power sander for this particular detail, the pattern can also be made with circular shapes (cups, bowls, etc.) and scratching tools to impart a similar effect.


Straight from the Tree

Although faux-beam shelves offer a lot of advantages to DIY installers, they are limited

to a simple box-like appearance, unlike an actual multidimensional wood slab with its

live edge intact. Wood lovers know that sometimes you just can’t compete with the unique character of certain pieces that come straight out of nature.

To install smaller wood slabs 2”-3” thick, you can find ready-made metal brackets which can be fastened to the wall and anchored to the studs. The brackets include metal rods that extend outward at right angles from the wall, and the solid shelf must be drilled through its rear edge so it will slip onto the bracket with the rods inserting into the holes and supporting the shelf from within. Although this sounds simple in concept, the operation requires a high-torque power drill, expensive drill bits, and precise alignment so the shelf holes marry with the rod placement like keys in locks.

Installation only gets more complicated as the slabs get larger. As they increase in size, the slabs get substantially heavier, and lifting them into place can require professional equipment. These large slabs are usually supported by 1” threaded rod driven at 90 degrees into the solid wall framing. The slabs are carefully drilled out to receive the threaded rods along the rear edge, in the same way the wall brackets interface with the mantle as described above.


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