Home Projects Home Decor Build a Fireplace Surround and Mantel

Build a Fireplace Surround and Mantel

Today I’m going to show you how to build a fireplace surround and mantel.  The design has a classic and beefy look and it would be a great upgrade to any bare fireplace wall.  I used some old circular sawn walnut that I got from a local sawyer south of Nashville for the box beam mantel.  The surround is made from standard 3/4″ MDF with some pine trim.  I used pocket hole joinery to make assembly a breeze and the surround was painted white to accent the natural walnut mantel.  Keep reading for all the details, but first let me tell you where I built the project to go.

Late last year I was approached by my friends Jamin and Ashley from The Hand Made Home.  They asked if I would make a fireplace surround and mantel for the local Ronald McDonald House here in Nashville.  I jumped at the opportunity to get involved and be able to give back to the local community.  The transformation they put together in this room with the help of Lay-Z-Boy and some craftsmen (myself included) was amazing!  You can read all about over at their reveal blog post.

It was such an honor to help make a room more inviting and comfortable for families going through some very hard times.  And how awesome is Ashley’s painting and decorating??? Now let me show you how to make your own!

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Here is what you’ll need for the project:


  • (1) 8′ x 4′ 3/4″ MDF
  • (1) 2′ x 2′ 1/2″ MDF
  • (2) 8′ 1×3 pine boards (milled to 1/2″)
  • (1) 10′ 1×4  pine boards
  • (1) 8′ 1×3 pine furring strip
  • (1) 10′ x 6″x 3/4″ walnut
  • (2) 8′ x 8″x 3/4″ walnut
  • 1-1/4″ Pocket Hole Screws

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Designing the Surround and Mantel

When Jamin and Ashley contacted me, here is the picture they shared of the current fireplace.  It was really lost on that wall with just some trim around it.

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And here is the photoshopped picture or what they said they wanted it to look like afterwards.  They wanted chunky and simple.  They were in luck, because I love chunky and simple!

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I drew up my version of the fireplace and mantel and sent it over.  They loved it and we were off to the races!

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 Building a Fireplace Surround

Obviously your build will need to modified to your space, so use my measurements for reference and adjust as needed.

The surround is made of two pillars support and a MDF box beam header. The box beam header will support the reclaimed box beam mantel. The surround is finished with pine face trim along with cove and crown molding for some added detail.

Begin by cutting the front and sides for the pillars out of 3/4″ MDF.  Drill pocket holes on the back side of the front piece and connect the sides with 1-1/4″ pocket screws and glue.

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Cut 3 inner pillar supports per pillar out of 1×3 furring strips. Use a pocket hole jig to drill pocket holes in the ends of the supports and attach one at the top and bottom and one in the middle. The top support will later be used to secure the MDF box beam to the pillars.

DIY Fireplace Surround and Mantel-6DIY Fireplace Surround and Mantel-8 Cut a 12″ long 6-1/2″ wide piece of 1/2″ MDF or plywood and secure it to the bottom of the front piece.

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Use 6″ wide strips out of 3/4″ MDF to trim out the bottom of the pillar. Cut miters on the pieces to wrap around the edges and attach with glue and brad nails.  Cove molding will cover the 1/2″ MDF sticking up in the front later.

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Next cut the trim pieces for the front of the pillars. I planed down 1×3 pine boards to 1/2″ thick but you could also use 1/2″ MDF if you don’t have access to a planer or 1/2″ pine.  Attach with glue and brad nails.

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This should leave a 3″ gap at the top.  Fill this spot with a piece of 1/2″ MDF.  The crown molding will cover this portion later.  Note, if your crown molding is something other than 3″ tall when installed then you’ll need to adjust the trim and this piece.

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Fill all the brad nail holes with wood putty and sand flush. The cove and crown molding will be installed once the pillars are attached to the wall to account for any wall variations.

The MDF box beam is made from 3/4″ MDF and 1×4 pine supports and has a solid front and bottom with an open back and top. Cut the front, bottom, and sides to size and attach them with glue and 1-1/4″ pocket hole screws.

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The back support is made from a pine 1×4.  Connect it to the sides with pocket hole joinery.  When installing the surround you will drive 3″ screws through the back support into the wall.

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Cut 4 top support pieces to fit between the back support and the front.  Attach the pieces with 1-1/4″ pocket hole screws evenly spaced along the beam.  Add a small 3-3/4″ brace between the bottom and back support piece and attach with pocket screws.

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You now have the main assembly of the fireplace surround complete!

Build A Box Beam Mantel

The mantel is 6″ tall and 8″ deep and built from some old circular sawn walnut I got from a guy out in the sticks.  Using miters you can get a great looking box beam mantel that is a fraction of the weight (and cost) of getting a true full sized beam.  Here is the walnut I started with.  We call this barn fresh, just don’t ask what those stains are from because I don’t know and I surely don’t want to find out 🙂

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To keep the character of the boards but be able to join them securely, you need to flatten the underside of the boards and get straight edges.  I did this using a combination of my jointer and planer.

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On the other side of the board, use 80 girt sandpaper in a random orbital sander to knock down all the roughness.  You can get pretty aggressive with 80 grit and not remove the saw marks.  Come back with 150 grit to smooth everything out and you’re done sanding.

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For a continuous look on the box beam corners you will need to cut the sides and the front with complimentary miters.  I squared up the ends of my walnut using my Mobile Miter Saw Station then cut the miters by tilting the saw 45 degrees to the left and then 45 to the right for the complimentary angle.

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The mitered front and sides are held together with just glue.  I used some homemade 45 degree clamping cauls to make this glue up a breeze.  Do yourself a favor and make 8 of these to help you glue this joint.

DIY Fireplace Surround and Mantel-24DIY Fireplace Surround and Mantel-29 After the front and sides are glued up you can add the top and bottom.  They are joined to the front and sides with 1-1/4 pocket hole screws.  Use clamps to hold the top and bottom in place and work your way down the entire mantel securing them in place.  I came back later and cut the sides flush with the top and back with a handsaw.

DIY Fireplace Surround and Mantel-26 DIY Fireplace Surround and Mantel-27 DIY Fireplace Surround and Mantel-28 DIY Fireplace Surround and Mantel-34 I finished the walnut with some satin General Finishes Arm-R-Seal and it it turned out amazing!

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I did not do the final install on the fireplace surround and mantel as Jamin and Ashley had some local contractors that did the painting, shiplap and install.  I’ll give you a few tips though on how it was installed even though I don’t have great pics.

The pillars were attached to the wall by first screwing a 2×4 to the wall vertically then placing the pillar over it and driving a screw through the side of the pillar into the 2×4.  The MDF box beam is then screwed down to the pillars and into the wall.  Finally, the walnut mantel rests on the MDF box beam and screws through the back of the top secure it to a 2×4 that is attached to the wall studs.

Here are a couple pics from the install.

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After the pant and the shiplap install it turned out amazing.  Here is a before and after…I’ll take the after!

DIY Fireplace Surround and Mantel-42 If you want some other great home decor projects then check out the Home Decor section of my site.

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