DIY Fireplace Overmantel Project – Lessons Learned

What? You’re NOT planning to build a fireplace overmantel?!  Believe me, no worries!  Not everyone needs a DIY Mirror Tile Overmantel.

However…I always seem to find at least one tip from tutorials I read that are of value later.

So here’s a takeaway tip for anyone: DO NOT (ever, ever, ever) leave things on the top of a ladder…even if you think you’ll be right back.  Someone might ring your doorbell and you go answer it.  Then they leave.  Then you pour coffee.  Then you return to the project but forgot you left your camera up there.  Then you move the ladder and the camera falls seven(ish) feet onto your blissfully unsuspecting head below.

Yep…learned that first hand.  Idiot!  I am very grateful that it wasn’t a drill, or a screwdriver…because a couple of times I left them there for a “quick sec.”  Yikes…

Lives saved…you’re welcome.

And if you ARE thinking of building a mirror or overmantel like this, here’s how I did

Although I thought this might be a two-week project, it took me “considerably” longer because I made it up as I went along…i.e., I had to tackle several unexpected problems. But problem-solving is at the heart of every true DIY project. You just have to think your way through it.  It’s worth it in the end.

fireplace overmantel greige mirror fireplace mirrors

Ready? Here we go.

You’ve seen this picture (over and over again, lol):

Screen Shot 2016-02-02 at 8.01.59 AM

Sussan Lari, Architect; Photo by Tim William

It’s the inspiration for the project. I found it on Houzz by Architect Sussan Lari.

If you recall, I like to plan out and visualize my big projects using my computer (read about it here) and doing so helped me make some early decisions about the basics of my plan.

I purchased seven packages of 12-inch square beveled mirror tile from Lowe’s (there are six in each $20 package)

and quickly encountered my first challenge: adhering them to the wall.

Really? A challenge right out of the starting gate????

Yep! It seems many of the mirror adhesives eat away the finish from the back of the mirror unless it’s electro-copper plated. In fact—no lie—one of the actual mirror adhesive products had this disclaimer: “do not use on mirrors.”  WTH!?

My original plan was to screw a thin piece of wood to the wall (so as not to damage the drywall) and attach the mirrors to it, then build the moldings around it…but—after researching the best adhesive–I ended up with a new plan.

Command Strips.

Now think about it: thirty to forty mirrored tiles stuck on a wall….above a fireplace that we use every night from autumn to spring… Those tiles need to be absolutely, COMPLETELY SECURE. (I’ll let you ponder the horrific ramifications of them NOT being absolutely, COMPLETELY SECURE.)*


via 3M

I’ve used Command Strips to hold some pretty heavy pictures and platters on the wall. So, I gave the 3M customer service folks a call and they said they thought this would be a safe application IF it was on a sealed surface (i.e., painted versus wood) and IF I followed the directions completely.

It also meant I could skip the wood layer and secure the mirrors directly to the wall.

I bought economy packs of the largest size strips, each pair is designed to hold 4 lbs. Each tile was about 1.5 lbs each, and I overkilled it by using three pair of large strips per tile.  (In do-over world, I would recommend using four sets and put them in each corner…I am the queen of overkill.  But I am also stupid I skimped and used three.  Spend the $20 extra freaking dollars…use four sets!)


clean-the-mirrors attach-hanging-strips

You have to follow the directions to the letter to get the best adhesion. So, I cleaned both the wall and the tiles with rubbing alcohol, waited until each was dry, and put the tiles on the wall, completely following the manufacturer directions.  When using these strips to adhere anything, my own mantra is “no click, no stick”. It’s not enough for the velcro-like strips to grab…you have to hear the click to know they are secure.

I put up the first row of tiles, then the second. Then waited a day, then tested and tested them to make sure they were secure.


Everything was going smoothly until the fourth row, when I discovered a slight size variation in the next pack of tiles. The new pack was slightly smaller (less than a quarter inch) than the last pack…which meant gaps…which would mean the wall would peek through, which could mean spoiling the effect.


I opened each of the three remaining packs and checked them against a tile that was the correct size. One pack was spot on with the spec tile, one was smaller, and one was actually a bit larger. (To clarify, each of the six tiles in the pack matched, but each pack had variations.)

I went back to the store and bought six more packages. Same thing. Bottom line…I was going to have to fudge a little here and there…some of them might be slightly off…(sigh). If I needed to, the Command Strips would let me reposition (though I really wanted to avoid that).

So I continued lining up the tiles and building up the rows…sometimes offsetting a slightly-too-large tile with a slightly too small one to even it out.

I guess if you look at it with “inspection eyes” you might notice that not all the corner joins are perfect. But the dark wall color camouflages any gaps and when you step back and look at it, you see the whole effect…not individual tiles.


Onward and upward! Seven tiles tall, five tiles wide.

Again, I jiggled, pushed and pressed on each tile to make sure it was secure.

Now I could begin to trim it out with the wood.

Because the mirror wasn’t as deep as the fireplace, I decided not to have the trim project/extend from the wall as much as it did on the bottom of the fireplace. I cut 3/4″ plywood into two strips (7” wide by the exact height of the mirror) to butt up against the sides of the mirror and use as the base of the overmantel “frame.”  After attaching the plywood, I would add the decorative fluted trim aligning the top layers with the ones on the existing fireplace below.

However, when I butted the wood along the side edge of the mirror, those slight variations in tile size meant that the side edges were also “slightly” uneven; which meant that I had to deal with those small gaps again.

Now, for some reason, I didn’t take pictures of this.  So, I created this one to illustrate my challenge (it’s also rotated for ease of viewing):


Instead of butting the wood against the side of the mirrors, I decided to overlap it slightly along the beveled edge, enough to reclaim a straight line and hide the gaps.


And that meant I had to raise the outer edge of the wood so it would rest evenly against the wall.  I cut and glued several 3/16” x 4” x 2′ wood strips to the underside, outer edge of the ply,


overlapped the inside edge of the ply just over the edge of the bevel mirror, and screwed it into the wall studs using wood screws (being careful to countersink). I was also very careful NOT TO OVER TIGHTEN the screws along the side that overlapped the mirror (so as not to crack or loosen the tiles).


(Btw, I also sanded the edges and prepainted all the wood before attaching it to the wall. I expected to give everything a final coat, but no sense fighting heights for the early coats.)

I ordered millwork to match the bottom of the fireplace from the wonderful, helpful, and encouraging local lumber and millwork store. (Thank you, Mosher Lumber in Clarence, NY!!).  (Really? You didn’t think I was going to rout this myself, did you?!)

I centered and attached the plinths using finish nails and my nail gun; then cut the fluted panels to the proper size, sanded and painted them, and used finish nails to attach them to the top of the plinths and the ply.   (But not being careful to take a quality photo.)


Next it was on to the top. Time to build the main part of the trim.

The top edge of the mirror had the same issue as the sides: the variations in the 12-inch tiles (give or take) left the top edge slightly uneven in the same way as the side was.

This part was going to be a little tricky since I had cut the side ply and molding to end in line with the tile.  SO… to cover the scant edge of the bevel, as I had before, I needed a new plan.  (In do-over world, there would be a better way to do this..but remember, I was making this up as I went along.)

Instead of gluing the thin wood strip to the back of the trim, I screwed scrap sections of quarter-inch ply directly to the wall. (And later added a second row just above it.)



This time I added the “bevel overlap” wood from side to side between the sides of the “frame.” The wood I used was the same 3/4″ thickness as the ply on the sides.  I didn’t take a photo from the top of the ladder, so I illustrated what I did here:


And this is what it looked like after I added the wood:


Why all the thin wood on the wall above the mirror?

The next part was to add the large mantel “box.”  It would need to rest on the side parts of the frame, project out just slightly past the front edge of the fluted trim, and ideally line up flush against both the wall and the horizontal piece that leveled out the edge of the mirror.



And one other thing: I needed to securely screw it into the wall.

Yikes!  All this thinking!  My brain was exhausted!

First, I built the box.  Next I added layers of wood on the sides to bring it to the proper depth (projection) as needed. Then sanded and primed it.



I added plywood to the wall on the studlines so I could securely screw the box to the wall (again, making sure the box would rest on the side moldings and fit like a glove against the wall and horizontal trim).


I centered the box above the side moldings and secured it with wood screws to the plywood that had been attached to the studs.



Holy crow! Lifting that wood all by myself while teetering precariously atop a 10-foot ladder! I had to stop for a minute to admire the fact that I’m still pretty strong for an “old chick”! Yay, me!

Now it was FINALLY time for the fun part: mitering and final trim work. There are lots of great tutorials and videos how to get the perfect miter. I used this one by the FABULOUS Leah at SeeJaneDrill as my primary resource.

Using finish nails, I added simpler flat moldings to the top and bottom of the box.

Next, I cut a 1″ x 3″ to extend about 3/4″ beyond the edges or the top moldings.  Then I added the crown molding to the edge of the 1″ x 3″ and nailed the whole thing to the top of the box.


Were my miters perfect? Nope. Hey, don’t judge, this was the first time I ever mitered anything!

Using my new best friends, Mr. Spackle and Ms. Dremel, I touched up any gaps and sanded off any overlaps. I might not get an A in carpentry, but I challenge any eagle-eyed critic (I’m looking at YOU, Mr. D&D, and YOU, Pops) to notice it from ground level. And frankly, it looks pretty darn close at eye level, too.

More “Yay, me!”

The final steps were pretty basic: fill holes, caulk, spackle, and paint.

Then stand back and enjoy hearing your family proclaim your awesomeness!  (Then move the furniture into the rightful places and maybe rehang those pictures.)



fireplace overmantel greige mirror fireplace mirrors



* All awesomeness aside, this was a DIY project.  I am not a professional and am not giving professional advice.  I DIY as a hobby and the steps listed above are the processes I used to complete this project.  Any DIY project is assumed to be “at your own risk.”  ALWAYS pay attention to manufacturers’ directions and safety instructions.


  • Rose

    It’s lovely. Good work.

  • Lol….I sure am glad to see that I am not the only one who does trial and error projects! I KNOW you put a lot of time into this because I have been there too many times to count. This came out just beautiful! I might be a bit too old to tackle this myself but it doesn’t mean I still wouldn’t try : )
    We purchased our home about 3 1/2 years ago and I had so many projects that I wanted done. Unfortunately, hubby got cancer and our plans were put on hold. We are just now at the point of getting back into things and after seeing this, I will be making some further adjustments with my plans! Thank you so much for sharing your full experience here. I think a lot of people take on projects that never get finished but you show that with patience and persistence, it can be done!
    I love it!

    • EmDirr

      Thank you for such a nice comment, McGypsy! Encouragement is a generous gift. It seems so many bloggers knock off whole room projects in a week or two. Too much going on around here for that to be possible! Plus that procrastination habit of mine…

      But your story is so much different…you’ve been tackling a much more important project! I hope things have gone well with your husband’s treatment. Such scary twists and turns Cancer can take. God bless you on your journey!

  • I think this is so beautiful; however, from experience 3M command will let go under high heat like a old antique wood burner insert. I would suggest using DUROCK Next Gen 1/2 in. x 3 ft. x 5 ft. Cement Board to place the mirrors on and attaching it to the wall. Maybe use Weldbond 14.2 oz. Interior and Exterior All-Purpose Adhesive to connect mirrors to the cement board. IT is also a good idea to ask Home depot experts for some advice on adhesives over a fireplace or call around places that do this for a living and see what they use. Thank you for sharing and I will definitely give this a try.

    • EmDirr

      Great, thoughtful comment, Rhonda! I am all about safety on this project and appreciate your suggestions! I actually did talk to the hardware store folks and they were the ones who recommended the “don’t use on mirrors” adhesive. Also checked with a building professional, who suggested leaving it to a professional.

      I will be testing my mirrors frequently…we use the FP almost every night…I checked the wall last spring and it does not get warm. I’m thinking it’s heavily insulated.

      However, I think your suggestions are really good ones. Can’t go wrong trying to maximize safety! Grateful for your feedback!

  • Absolutely gorgeous! What drew me into the article was the color of your walls. We did grey also several years ago and I still love it. Unfortunately we do not have a fireplace and not sure I’d want one but I’d take it in a heartbeat with that beautiful mirrored wall over it!

    • EmDirr

      Thank you Eds! I love the color, too… Especially juxtaposed against all the white and bright. Since it’s open to the Fam Rm, I used it in the upstairs hallway as well but it was pretty dark. The mirrors changed all that as they reflect light down the hallway. Bonus!

  • Jan

    It looks fabulous. You should feel very proud of yourself!

  • robjodiefilogomo

    Em—this is truly amazing!!
    Of course, I know I already said that when I saw the finished photos…but now seeing all you had to go through!! Golly begeezers!!
    I’ve used those command strips before and they’ve worked well on a picture attached to concrete (in the basement). So hopefully you’ll have no issues with that part of it!
    And to think you cut all that wood yourself?? Quite the DIY project—-great job & look out HGTV!!