DIY Fireplace Mantel


This was a fireplace mantel and I built entirely of cherry. I fabricated every component myself except for the crown molding and cove molding.

This diy fireplace mantel was built for my own house, the fireplace is non-functional. I looked into getting it converted into a gas log fireplace, but it would’ve just been too much effort and expense. There was an existing chimney but the furnace was vented through it and that would also have to be modified to have an additional vent added, and a new gas line run. It would’ve been several thousand dollars not including the fireplace insert, and that just wasn’t in my budget at the time, so it would remain a decorative fireplace.

When I bought the house the wall was covered with a giant mirror, and the mantle was made of crown molding around some marble tiles. I didn’t like it, I thought it was ugly, so I set about designing a new mantel.

First was the demo of the existing fireplace.

I decided to add a receptacle, in case I ever decided that I wanted a TV over the mantel.

I found the design for the fireplace to be really challenging. The portion of the wall that crops out seemed very large in proportion of the room, and my main concern was that I would have this room with this massive fireplace that was way too big and just didn’t fit, but if I made the mantel too small, then it would be out of proportion with part of the wall that crops out, and would also look wrong.

Before embarking on a large project and buying a few hundred dollars in wood. I decided I would use Google Sketchup and it’s match photo feature to come up with a complete design of the fireplace before I started building it. I’m not an expert with Sketchup, but it works great for keeping track of dimensions and the match photo feature is pretty awesome. If you’re not familiar with the photo match feature the way it works is you actually take a photograph, then build a model in Sketchup. Then you can import the photos you took and they will get applied as textures to your model, it’s an incredibly fast way to add a lot of detail to an otherwise bland model.

The first step is to take some pictures. I took pictures of 3 different walls, here are some of the pictures I used.

front wall:

left of the fireplace:

wall where the mantel needs to go


wall to the right of the fireplace:


rear window:


After taking some pictures, I measured the room and the portion of the wall that crops out. Then I built a model of the room in Sketchup. I’m not going to cover the photo match process with Sketchup because there are two videos that already do a great job of it.

If you watched the videos, you will understand the importance of placing the origin and axes in Sketchup. I chose the lower left corner of the wall the mantel will be installed on, where the base molding ends as the origin.


Here is the model of the room that I created.



and here is what it looks like with the photos applied.

The bulk of the design came from a book I read a book called Making Mantels, by David Getts.  This was my first time building a fireplace mantel but was not my first woodworking project of this complexity. I highly recommend this book, it provided many ideas and inspiration for this project. See Chp 8 “Fabricating a Complex Mantel”, and you will see a mantel very similar to mine, I proportioned things to be a little more “beefy”, the molding on mine does not extend across the bottom of the firebox, and the raised panels on the frieze are different.

Here was one of the advantages of using Sketchup, once I had built a model very similar to the book I realized that I didn’t like the way the raised panels on the frieze were pointed on one side, I changed them to be vertical.


I measured the width of the wall the mantel would attach to and decided leaving about 3 inches of wall on each side of the mantel its furthest extents would look best. That is how I established the width of the Mantel to be 95-5/8″. For the height I used the Golden ratio of 1 to 1.618 as a guide, this would give a height of 59″. After tinkering with model in Sketchup I felt it looked best with a height of 56″.





I built the model of the mantel separately from the room model, just by using the dimension of the mantel shelf as a basis for everything else. Once I had the model complete, I imported it into the room model.


Once I reached this point, I had enough confidence in my design, and was no longer concerned about the fireplace being too big for the room, or too small for the portion of the wall that stood out.

Now I was ready to start building this beast. Here’s a picture of all the lumber that I used build the fireplace, I didn’t actually use all of this, I still have a fair bit left over. I like to buy quite a bit more than I need that way there’s plenty there to take care of mistakes, and its nice to always have some nice lumber sitting around the shop. When I decide to build a small project, I usually have enough wood on hand.

Here I’ve cut pieces for the pilasters. These were cut from 5/4 stock, then jointed and planed to precisely 3/4″.

The raised panel profiles were cut with a MLCS Pro Cabinetmaker 6 piece router bit set. ( )

Here I’m assembling the front panel for the pilasters. I assembled it quite a bit longer than I needed, then trimmed it up to final size using my miter saw.

The edges were mitered on the table saw and joined with glue and biscuits at a 45 degree angle. This mitered edge is one of the most visible parts of the fireplace, and its also a little tricky to get a miter like this perfect, so take your time. When you do assemble the miter, put a piece of tape along the entire length of the outside of the joint for both pieces. This is to make certain that no glue leaks out on to the visible surface, as this will show up through your finish. I added several more pieces of tape to hold things after taking this picture.

I made a plywood template just like was done in the book to provide some structure to hold the pilasters to the frieze.

This also made it easy to build the pieces in the garage and carry them inside to verify the fit and size as I progressed along.


Next I built the raised panels for the frieze. I assembled it first without the end pieces (i.e. the rails ), because they need to have a mitered edge just like the pilasters. If glued it all together here, it would be difficult to miter the ends of such a wide piece. This way I can test the overall fit with rails just inserted, but not glued, then I have a very small and manageable piece to cut the miter on.


Here is the two end rails in place, but not glued. Next I mitered the rails, then glued them in place. Last I trimmed the panel to final size on the table saw.


Here is the assembled frieze panels resting om the plywood support.


I screwed the pilasters into the plywood support piece, these were glued and screwed from the rear side of the plywood. In this picture you can see the way that I attached the mantel to the wall. There is a small scrap of 2×4 pocket screwed between the two sides of the pilaster. Another scrap of 2×4 is screwed to the wall, with a scrap of 1/2″ plywood screwed into it. This scrap of plywood protrudes above the 2×4 on the wall and creates a little pocket for the 2×4 on the back of the pilaster to slide in. This worked really well since I could remove and replace a very large section of the mantel as I built it. Later on I added some large screws to fasten it permanently to the wall.


Here I am cutting some test pieces for the molding that surrounds the firebox.


Here the firebox molding is installed, but I still need to cut the profile, and attach it.


The firebox molding was attached with pocket screws, glued at the miters, and glued to a support block that fits in the gap between the pilaster and marble.


With the firebox molding finished, and an easy way to remove the mantel, I decide to start with a first coat of stain.



At this point I was also working on fluted panels that sit next to the raised panels on the frieze. I used a Router Fluting Jig. I practiced on some particleboard first before messing with a piece of cherry.


It worked really well once I got the hang of it, and it went surprisingly fast.


As you can see I just used a piece of plywood and some scrap lumber to hold the wood still while I did the work. I also had some two sided tape on the back of the panel. I screwed a few scraps down to act as stops so when the jig hit the scrap it would get the length of the flute perfect. You can see that I have already mitered one side of the fluted panel.


The only problem was that when I got to the cherry I ended up burning the wood a little bit probably because my speed was not quite right.


The burning wasn’t too bad, a little sandpaper cleaned it up just fine. Next I, stained and attached them to the plywood support piece.

At this point it was time to permanently fasten the mantel to the wall. I did this with by screwing some 4″ drywall screws through the mantel just below the fluted panels, into studs behind the wall. These screws were the covered up by a small piece of cove molding that wraps around the transition between the pilasters and frieze.


Next I fabricated some dentil molding. This was done by installing a dado set into my table saw, and cutting some dadoes into a long board. To get the spacing perfect, I cut some thin strips of 3/4″ plywood to act as a spacer between the blade and fence, rather than trying to move the fence by a precise amount, I just remove one of the strips, and trim a little off the scrap that keeps them from being pushed off the table as I make the cut.


Once that was done, I cut them into a bunch of little strips.

To install this molding I built a jig that the small pieces can rest on while being attached. I attached these pieces with glue and 23 gauge pins . About the same time as this, I cut and fitted the base molding for the pilasters.


Once the dentil molding was installed, I got started on mantel shelf. It is just a long piece of cherry with an ogee profile on the underside.


With the mantel shelf in place, I could start on installing and staining the crown molding.


All that was left was tape off the edges, apply some clear coat, and get out my good camera for some pictures.


diy fireplace mantel.




 Posted by at 6:13 pm

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