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How To Build A Fireplace Surround

Learn how easy it is to build a simple fireplace surround and mantel from MDF to beef up an existing brick fireplace.

How to build an easy DIY fireplace surround and mantel

In the first part of my fireplace makeover tutorial, I shared how to tile over a brick fireplace. Today, I’m going to share how we built out our existing surround and DIYed a new mantel. If you haven’t already you can also see my plans for the fireplace makeover.

Before we get into the tutorial, here’s what we started with:

A close up of a fire place

And this in an improvement on what it ORIGINALLY looked like when we moved in….

Fireplace with backs of built-ins painted Sherwin Williams Serious Gray

But now we’re here. The mantel (shelf) has been removed and the tile has been laid. Now it’s time to build the surround and make this look like a proper fireplace!

Simple tutorial on how to build a fireplace surround

How To Build a Fireplace Surround

When we took the old mantel shelf off we were left with a surface almost completely flush with the wall (one of the main reasons for this makeover).

Before we could tile the hearth, we covered the brick with ¼ inch MDF. We stuck it directly to the brick using some Liquid Nails and used our nail gun on the corners where the MDF met. We didn’t bother mitering the edges and just butted them since we knew it would be covered with trim later on.

Tiling over painted brick fireplace

We used the same sheet of MDF to cover the sides of the surround and across the top. We measured them to fit what already existed since the built-ins on either side preventing us from going any wider. We secured the MDF to the existing wood surround using our nail gun.

MDF columns to start building the surround

Next, I began to add some of the lattice pieces to the front of the hearth. We started by boxing it out (top piece, bottom piece then left piece and right piece). Finally, we cut the two small vertical pieces that would form the inner boxes.

The lattice pieces are attached mostly with liquid nails but with a few nails in the corners just to make sure they would stay in place. The lattice repeats on the side of the fireplace, too.

Shadow boxes using lattice trim for the front of the DIY fireplace surround
DIY fireplace surround and mantel

Building The Mantel

At this point we decided to build our mantel before deciding how far out we wanted to build the surround. It was one of those things that we just needed to see in real life and not just on paper.

The mantel itself is a very simple box. We purchased pre-primed 1 x 4’s and started by attaching the back board to the existing wall with our nail gun.

The bottom piece was nail in place and then the side pieces. Finally, the front piece.

No 45 degree angles needed again, since we knew the exposed sides would be covered by crown when we were done.

Note: In hindsight, it would have made more sense to build the box first and THEN install it. If you have a kreg-jig, pocket holes would work great to secure the sides. But our way worked fine in the end.

Building a box from wood for the mantel shelf

When we were happy with the box, we attached a 1 x 8 pre-primed board to sit on top and form the actual mantel.

Building out the surround using MDF

Once the mantel was built, it was easy to figure out how far out we needed the build the rest of the surround.

Again, we kind of just boxed it out, this time using 1/2 inch MDF. We attached the side pieces first, then nailed the front piece in.

For reference: our column/vertical pieces are 7 inches wide, with a depth of 6.5 inches. Yours may need to be bigger or smaller, but that may help you figure out what you need.

Then we added 1 x 4 pieces to the bottom of the vertical sides to create some depth. These pieces were cut at a 45 degree angle to create a clean, mitered edge.

By the way, we found the MDF very messy to work with (we are STILL cleaning up saw dust a month later). I’m not sure our circular saw was up to the job – a table saw would have made cleaner cuts – and the pieces were large so cutting them with our miter saw was a no-go.

SO, we just butted the edges and figured some spackle and sanding would help hide the fuzzy raw edges of the MDF (note: they did! The sides came out perfectly smooth and painted like a dream!)

Next up we worked on finishing the shadow boxes using 1×2’s. We only used the thin pieces of lattice for the hearth, they looked too wimpy on the main surround, so we chose 1×2’s for more dimension.

We always do the perimeter boxes first and then full in with the little pieces.  Doing it that way makes the cuts a lot quicker.  At this point the whole design really started to come together.

DIY fireplace surround in a living room

Fitting the Electric Fireplace

In order for the electric fireplace to sit into the existing fireplace surround, we needed to build a box for it to sit in.

The particular electric insert that we purchased screwed in on the sides only, so we decided to only do 3 sides to our box – left, right and bottom.

The bottom piece needed to be raised up from the ground enough so that to top of the insert would align with the top of the opening and cover an imperfections in the tile right around the edge.

We did the math and figured all that out, then screwed the wood into the brick with some masonry screws and as well as liquid nails.

MDF fireplace surround and hearth over existing brick

I forgot to take a photo before we attached the backer board to the wood but you get the idea, right?

At this point, the electrician had finally come and installed the outlet inside the fireplace so I was able to go ahead and finish tiling.  P.S. Did you notice the little red hammer? My kids love to help  and have kiddy versions of ALL our tools! 

We attached some crown moulding the front using various YouTube tutorials to help us cut the mitered edges.

The first piece of crown we bought was 4 ½ inches and too large. Even though it fit on the front under the mantle top,  we couldn’t get the edges to meet, so we had to go down to a 3 ½ inch piece.

How to make a fireplace surround from MDF

Finishing Touches

Next came the dirty part – lots of grouting, cleaning, spackling, caulking and sanding.

I sealed all the fuzzy edges of the MDF with a light coat of spackle, let it dry and sanded it with fine grit sandpaper. All the nail holes will filled with spackle and sanded once dry.

Finally, all the seams were filled with caulk. I made sure that the wood had no imperfections and was very smooth before priming it with 2 coats of my favorite primer and sealer. This stuff completely seals the wood so that you don’t ever need to worry about bleed-through.

Simple wooden fireplace surround with DIY marble tile hearth

I lightly sanded between each coat of primer to ensure that I was keeping the surface as smooth as possible. I allowed the primer to dry for 24 hours and then applied 2 coats of Sherwin Williams Extra White in a satin finish.

Then FINALLY, after what seemed like an eternity and a whole lot of late nights, we installed the electric fireplace insert.

How to build a fireplace mantel from scratch
Fireplace surround with electric fireplace

I was SO excited for it to be done that I had all my Christmas decorations back up before I took photos. Isn’t it beautiful though?

In the end, we pretty much built this entire fireplace mantel and surround from scratch. But I have to say it was worth it.

Our living room has been completely transformed! Our new fireplace is proportional, substantial and fits our space. It wasn’t the most difficult DIY project but it certainly was a little frustrating at times (I’m looking at you crown molding!) and more than a few swear words were uttered.

diy fireplace surround and mantel painted white with fall decor

We’re so happy with how it turned out and we very pleased that we DIYed the entire thing ourselves and saved a lot of $$ as a result!

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Fireplace with large white mantle and framing; grey and white herringbone tiling around fireplace and base

How to Build a Fireplace Surround and Mantel

Active Time: 6 hours 4 seconds
Total Time: 6 hours 4 seconds
Difficulty: Intermediate

Materials

  • Sheet of ¼ inch MDF
  • Sheet of ½ inch MDF
  • 1 x4 pre-primed boards (6ft)
  • 1 (one) 1 x 8 pre-primed board (length of mantel top)
  • 1 x 2 boards (2 - 3, 8ft boards)
  • Lattice Trim 
  • wood screws
  • brad nails
  • liquid nails
  • tape measure
  • level

Tools

  • Circular or Table Saw
  • Miter Saw
  • Nail Gun 

Instructions

Building The Base of the Surround

  1. Cover the brick hearth with ¼ inch MDF using Liquid Nails. Use a nail gun on the corners where the MDF meets. The corners don't need to be mitered, just butted together since they will be covered by trim in a later step. If you are tiling, this step should be completed prior to tile being installed.
  2. Use additional MDF to flank the sides of the fireplace, to create two columns, then another piece across the top. The width of these pieces will vary depending on the dimensions of what you're working with.
  3. Add lattice pieces to the front of the hearth. Start by boxing it out (top piece, bottom piece then left piece and right piece). Finally, cut the two small vertical pieces to form the inner boxes.
  4. The lattice pieces are attached mostly with liquid nails but with a few nails in the corners just to make sure they would stay in place. The lattice repeats on the side of the fireplace, too.

Building The Mantel

  1. We chose to build our mantel box before finishing the surround, so that we could visually see how far we wanted it to come out.
  2. The mantel itself is a very simple box. There's two methods to making it. The first is to build the box and then screw it to the wall with heavy duty wood screws. The second method is to use a kreg jig and pocket holes (preferred method). The second method, in my opinion, is more secure.
  3. We purchased pre-primed 1 x 4's and started by attaching the back board to the existing wall with wood screws.
  4. Add a support piece in the middle, then on both sides, by screwing wood screws through the pocket holes. Then nail the bottom piece to all the supports, and finally the front piece. (we did not do the middle support as everything seemed sturdy enough, so it's optional).
  5. No 45 degree angles are needed, since the the exposed sides will be covered by crown when we were done.
  6. When the basic box is installed, the 1 x 8 board for the mantel sits directly on top. Nail it down all around. It's important that this piece sits out far enough from the box below it that crown molding can be attached. You may want to play around with whether a 1x 8 or 1 x 10 works best for the type of crown you're planning to use.
  7. how to build a fireplace mantel

Finishing the Surround

  1. Once the mantel is built, it's easy to figure out how far to build out the rest of the surround.
  2. Box the side columns in, using ½ inch MDF. We attached the side pieces first, then nailed the front piece in.
  3. Then add 1 x 4 pieces to the bottom of the vertical sides to create some depth and act almost like a piece of base crown. These pieces were cut at a 45 degree angle to create a clean, mitered edge.
  4. Add shadow boxes with 1 x 2's to both vertical sides and the piece under the mantel. Start with the perimeter boxes first and then fill in with the little pieces.  Doing it that way makes the cuts a lot quicker. 
  5. Attach a piece of crown directly under the mantel ledge.The piece we used was 3 ½ inches. You may want to watch a YouTube tutorial to learn how to miter the edges of crown, it's a little tricky!
  6. how to build a fireplace surround

Notes

How much wood will vary depending on the size of mantel and surround you choose to build. We were constrained by what was already there, so we built to those dimensions. We also only have ceilings just over 7 feet, so the height has to be proportional to that.

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