How to Build a Faux Wood Beam Mantel

October 4, 2023

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Fearless DIY. Sharing building project tutorials and interior design tips. Let’s build something beautiful together. For more projects, design tips and behind the scenes, follow me @designtobuild.nicole

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Fireplace Makeover Phase one: How to build a faux wood beam mantel and make your fireplace the statement piece it should be!

Do you have an old dated fireplace in need of some modernization? We bought our home over 12 years ago and I have never been a fan of our fireplace, until this year….AFTER I completed the fireplace makeover.

The first step to this makeover, was replacing the boring, thin builder’s-grade mantle with a chunky faux wood beam mantel. And I’m here today to show you how I did it!

But first here’s a quick “before” look at our living room mantel…

fireplace makeover before

And here’s what the new mantel looks like now. Isn’t the transformation amazing?!!

fireplace makeover reveal

And now let’s jump into phase one of this tutorial. (Be sure to check back for Phase 2-Raised Fireplace Hearth DIY and Phase 3-Fireplace Surround Makeover; over the next couple weeks). Want to check out the entire fireplace makeover all in one place? Here’s the link!


How to Build a Faux Wood Beam Mantel:

Materials Needed:

Tools Needed for DIY Wood Mantel: 

Amazon Associate Affiliate Links Included

Step One: Remove Old Mantel

The first step is to get rid of your old mantel. The easiest way to do this is with these four tools:

  • Flathead screw driver
  • Hammer
  • Box cutter
  • Crowbar

tools to remove mantle

First, you’ll want to use your box cutter and cut the caulking between the whole mantel and the rest of the fireplace. Anywhere your mantel shelf is attached (i.e. wall, etc), run a cut with your box cutter…

mantel with boxcutter cut

Now you’re ready to shimmy your crowbar and flat head screwdriver in between the mantel and fireplace surround.

The easiest way to do this is to start with your flat head. Using a hammer, drive your flathead into the cut you made with the box cutter.

This will open up enough space to then wedge your crowbar in there, allowing you to work the crowbar up and down loosening the mantel top from the fireplace….

crowbar and flathead in between mantel and fireplace

If you’re lucky your existing mantel will come off with little muscle power. I wasn’t that lucky. 🙁 It definitely took some work.

removing mantel from fireplace

But finally, it came off…

mantel removed and ready for faux wood beam mantel

I personally didn’t want the crown molding around the bottom, so I ended up removing that too. And added my own trim, using 1×4’s…

mantel removed and trim added

Step Two: Build the DIY Mantel Support

Now you’re ready to build the cleat that will hold your faux wood beam mantel.

First thing, measure how long you want your mantel to be, then cut a 2×4 to that length. This will be your cleat support.

Next step, determine how wide you want your mantel to be. In other words, how far do you want it to stick out from the wall?

You’ll then cut 2×4’s to get you to that width. Be sure to keep in mind the width of the 2×4 you cut for the cleat support. Hopefully the picture below will help make this clear.

For example, I wanted my mantel to come about 10 inches out from the wall. So, I first took into account the 1.5 inches for my cleat support (2×4) and therefore cut my cleats 8.5 inches–totaling 10 inches.

NOTE: I built my support before attaching it to the wall. It’s much easier to add the cleats when you’re not working against gravity. Therefore, please note these pictures show the support after it was fully built AND THEN attached to the wall.

cleat for faux wood beam mantel

To attach the cleats to the cleat support, you’ll need to drill 1-1/2″ pocket holes into one end of each cleat. And then attach using 2-1/2″ pocket hole screws. I spaced my cleats out about 10 inches apart…

cleat for faux wood beam mantel

Note: If you have an outlet (like I have), you’ll need to make sure the length of your cleat support doesn’t cover the outlet. You may need to build separate cleats (one on each side of the outlet-like I did)….

cleat bordering wall outlet

NOW you’re ready to attach your cleat to the wall using 2-1/2″ screws. Make sure you are attaching your screws into wall studs. And it’s a good idea to use a level to make sure your cleat is straight….

level on cleat to ensure its straight

Where to place your cleat is dependent on how thick you want your mantel to be. I chose for my mantel to be six inches thick (bottom of the mantel to the top of the mantel).

Therefore, in placing my cleat, I made sure I allowed for plenty of room for my mantel. As you can see in the picture below, I still have about an inch and a half of the 1×4 still visible….

Underside of a fireplace mantel

Step Three: Build the Hollow Box

The old mantel is removed, the cleat is attached and now we’re ready to actually build the DIY fireplace mantel. When finished with this step, we will have a hollow box (without the back board).

Using 3/4″ plywood, cut your top and bottom boards to the length and width of your cleat you built and attached above….

Plywood for faux wood beam mantel

The board, in the picture above, is my top board of my faux wood beam mantel. As you can see, I made a cut-out to stuff all of my cords (TV, speaker, Apple TV, etc) down into. A great way to hide all of that unsightly mess. It will look like this…

Insert cut out of DIY wood mantel for cords

Next cut your side pieces. Rather than using plywood for the sides and front piece, I used 1×6’s. The 1×6’s give a more authentic wood look for the areas you’re actually going to see.

Attach your side boards to the top board using wood glue and 1-1/2″ wood screws (These are my all-time favorite screws to use in any project)….

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side board of faux beam

At this point your DIY wood mantel should look like this…

both sideboards of faux beam

Now you’re ready to attach your bottom board….

faux wood beam mantel built

Cut your front board to size and attach it…

front added to faux beam

NOTE: As you can see, we didn’t cut a board for the back of the mantel. There’s no need to, since the back will be flush against the wall.

Step Four: Attach DIY Wood Mantel to Cleat

Now that you have the faux wood beam built, you’re ready to attach it to your cleat.

This is where mine got a little tricky and required some math. I knew this issue was coming, but decided to face it once I got to it. My beam would only slide over the cleat so far before it hit the molding and columns of the fireplace. (Sorry for the poor quality photo 🙁  )…

faux wood beam mantel hitting fireplace

Basically, I had to measure how much the fireplace was blocking the bottom of my faux beam and cut those spaces out, using my jigsaw….

faux beam post cutout

With some math and playing around with it, I finally got it to work….

newly built mantle for fireplace makeover

Please don’t let this scare you…If I can do all that math and work through this snag, you can too! Math is, by far, my weakest subject!! You’ve got this!!!

Once your faux wood beam is in place, you’re ready to attach it to the cleat. Using 1-1/2 wood screws, attach the beam to the top, sides and front of the cleat.

Fill in all of your nail holes and your new wooden mantel is ready for stain.

I chose Jacobean by MinWax for mine. I love this dark color stain.

Amazon Affiliate Link Included

fireplace makeover with faux wood beam

Update: A More Recent Look

It’s been a few years since my DIY wood mantel makeover. Over this time, my style has changed.

One of the biggest changes I made was sanding down the mantel and applying a new stain. While the Jacobean stain gave a more rustic mantel look, my new stain is more of a modern look. I chose MinWax Golden Oak. I love how it really toned down the color.

Bye-bye rustic vibes; Hello organic modern.

All white fireplace with a Jacobean stained mantel

Of course, my decor has since changed a lot too. Here’s a look at my fireplace today…

All white fireplace with a faux wood beam mantel

Want to build the hearth? Here’s exactly how I did it!

I hope I inspired you to update your own mantel. This super easy DIY project makes such a huge impact. Whether you have a stone or brick fireplace, a box beam mantel would look great!

As always, please let me know if you have any questions. I love helping you turn these DIY tutorials into the real thing.

Let’s go beyond the design to build something beautiful together!

Until next time,

Happy Building, Friend!!

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  1. Deb

    Looking forward to phase 2

    • Nicole Nigg

      I’m glad you’re enjoying the tutorials!

  2. Jeffrey Buchanan

    It would look more like a real beam if you mitered the corners. I just built one for one of my fireplaces and it turned out great. Looks like a solid beam.

    • Nicole Nigg

      Hi Jeffrey,
      That’s awesome! I’m sure it looks amazing! Way to go!

  3. Jackie

    This turned out amazing!!! I love it so much. We are doing some kitchen cabinet refinishing this week, but I would love to do this for our next project. Thank you so much for sharing!!!



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