Ron Hazelton

How to Install a Fireplace Mantel on a Stone Fireplace (Step-by-Step)

Carpentry

Fireplaces

HOUSE DOCTOR Transcript

HD026 “FIREPLACE MANTEL” from episode 618

RON:

I'd like you to meet Bob. Hey Bob, thanks for having me over.

BOB:

Thank you, Ron, for showing up.

RON:

You're holding something there in your hand. It looks awfully a lot like a mantel.

BOB:

It is. It's an oak mantel that we've had for about three years, and my wife and I always wanted to have one, but I wouldn't have known how to put it up here, and I thought of you, the House Doctor, so that's where we need your help to install it.

RON:

Beats the heck out of me.

BOB:

Well, it'll beat the hecks out of both of us.

RON:

So what, has it been the stone that's bothered you, sort of, you weren't sure how to attach it to that?

BOB:

It's so irregular that I didn't know where to begin.

RON:

Okay, good. I'll tell you what, let's start by just deciding how high you want this. Obviously, we're going to center this over the firebox. Now, there is a code requirement that says we've got to have at least 12 inches from the top of the firebox to any combustible material. Of course, this is wood, so we have to be a minimum of 12 inches above here. We're probably more like 14 right now. Now, let me hold this. Just go back over to the side of the room.

Just take a look at it, because it's really up to you, whatever you like the looks of here.

BOB:

I think that looks good, just where it is right there.

RON:

Right there? Okay.

Well, hold her in. Let me get my pencil out here. Let's just make a little mark on the stone right here. Okay, then we can take this down.

Now, mantles like this are designed to be attached to a ledger or a piece of wood, which in turn is attached to the face of the fireplace. I'm placing this just about where we want the top of this mantel. We're going to put a four-foot level up here.

Get this level left to right. Okay, let me see it. Okay, Bob. There we go, right there. All right. Now, that's level. Now, let's take our four-footer down.

What I'm going to do now, this surface is very irregular. So, I want to attach this at places where the ledger strip here is going to be in contact with the stone. So, there's one right there. Looks like we probably got one right here. You got one over there, Bob?

BOB:

Yeah, right there.

RON:

Right here? Okay.

And I'm going to put a mark over here. Even though I'm not in contact, we probably can shim up behind this because I want something out here closer to the end. So, maybe we'll put one right here. Okay. Now, let's take this down. We'll drill some pilot holes.

Now, there's the pre-drilled hole in our ledger. And this is a carbide tip drill right here, small enough to slip through there. I'm just going to be marking the stone at this point so I can make the holes in the stone align with the holes in the ledger.

It doesn't have to be very deep, just enough to make a mark. That's the last one. This comes down, and there's our mark.

We're going to attach this ledger to the stone using what's called a lag screw. It's got a hexagonal head and a very coarse thread. But, of course, you can never put this directly into the stone. First, we have to put in what's called a lag shield or anchor. It's a piece of very soft metal. It's actually split. You see this right here? As I screw this in, it sort of pushes the two halves of this apart, and it'll jam it on the inside of the hole. That's what's going to hold everything in place. Now, we've got to drill a hole that's large enough to accept this lag shield. And for that, of course, we need a carbide bit. And that should be just about right there. This is a 3 1⁄8 inch bit. It should be just about perfect. Now, there's the mark we made earlier. Let's go ahead and drill our hole.

Now, it's just a matter of taking the lag shield or anchor and slipping it in the hole.

Now, to actually attach our ledger, we're going to take our lag screw with a washer on it. Push it through the pre-drilled hole. Why don't you go ahead, Bob, and do yours over there. And then we're going to line up the screw with the lag shield right there. And we tip it up, and we'll screw this in as far as we can by hand. Now, because we actually used this as a template to drill those holes in the masonry, all these holes should line up without any problem.

Let's make one final check here to make sure that our ledger is, in fact, level. It looks good. And then every place where the wood is actually in contact with the stone, like it is right here, we'll go ahead and snug this up with a socket wrench. We've got it. Okay. But over here, for example, where we've got a space behind the board, we're going to want to insert a shim. It's a small block of wood here. Get it in position…there we go. And then we'll tighten the lag screw down against that. That will prevent us from bowing this ledger as we tighten up the lag screw.

Now, actually installing the mantel is very simple. I'm going to drill four or five pilot holes here on the top of the mantel. Okay, now, Bob, if you can grab the end over there.

BOB:

Okay.

RON:

We're just going to set this up on the ledger. Okay. There we go. Okay. We'll make sure that it's centered. And then through those pre-drilled holes, I'm going to drive an 8-penny finish nail right into the top of that ledger.

Well, there she goes, Bob. After three years, she's finally hanging over the fireplace.

What do you think?

BOB:

That really looks beautiful. It came out nicer than I expected. Thank you very much, Ron.

RON:

Well, you're very welcome. And we, of course, went ahead and countersunk those finish nails, put some putty on the top. You know, one nice thing about hanging a mantel the way we did here is it's quite strong, strong enough to support the weight of a clock and this brass horse over here. You don't have to worry about that coming down when it's put up this way.

So, listen, thanks for having us over. I'm glad, after all this time, we were able to put this up and figure it out together. And please enjoy it.

And if you've got a mantel that you're thinking about buying or one that's been hanging around waiting to be put up, well, now you know exactly how to go about doing it.

From the archives of the House Doctor

A fireplace mantel is one of those upgrades that instantly makes a room feel finished. But if your fireplace is faced in stone, the idea of mounting anything to that surface can feel intimidating because stone isn't flat, isn't predictable, and doesn't exactly forgive mistakes. In this video Ron shows you the right approach, making this a very doable weekend project.

What You'll Need

Your mantel (oak or the wood of your choice)
A ledger board (mounting strip) sized to your mantel
4-foot level
Pencil
Carbide-tip masonry drill bit for marking hole locations
Carbide-tip masonry bit sized to match your lag shields (check the anchor packaging — commonly 3/8")
Lag shields (masonry anchors)
Lag screws with washers
Socket wrench
Wood shims
8-penny finish nails
Hammer or nail gun
Wood putty (to match your mantel's finish)

Frequently Asked Questions

How much weight can a mantel installed this way hold? A mantel hung on a properly anchored ledger board is strong enough to support typical mantel decor — clocks, framed art, and decorative objects — without concern, since the weight is carried by the lag-shield anchors in the masonry rather than by the nails alone.

What's the required clearance above a firebox for a wood mantel? Many codes call for a minimum of 12 inches from the top of the firebox opening to any combustible material, but requirements vary by jurisdiction and by mantel depth, so verify with your local building code before installing.

Can this method work on brick or other masonry, not just stone? Yes — the ledger-and-lag-shield method works on any solid masonry surface. The key on stone specifically is identifying the high points where the ledger actually makes contact, since stone is far less uniform than brick.

Step 1

Decide on Mantel Height and Check Clearance Code

Before you pick up a drill, figure out where the mantel should sit. Most mantels are centered above the firebox, but height is really a matter of personal taste. Hold the mantel in place (or have a helper hold it) and step back to view it from across the room before committing to a spot.

There is one rule you can't eyeball, though: building codes typically require a minimum clearance between the top of the firebox and any combustible material, such as a wood mantel. A common minimum is 12 inches, but exact requirements vary by location and by how deep your mantel is, so check your local building code before finalizing your height.

Step 2

Mark Your Placement and Level the Ledger

Once you've settled on a height, mark it lightly on the stone with a pencil. Wood mantels hang on a ledger board (also called a mounting strip) that gets secured to the fireplace first, and the mantel simply hooks or sits over it.

Hold the ledger against the stone at your marked height and set a 4-foot level on top of it, adjusting until it reads perfectly level left to right. This step matters because everything else lines up off this one level line.

Step 3

Find the Ledger's Contact Points on the Stone

Since stone surfaces are rarely flat, trying to force full contact across the whole board will be challenging. The way to tackle this is to identify the spots where the ledger actually touches the stone. Then, mark those points as those will be where you'll anchor the ledger.

For gaps where the ledger doesn't quite reach the stone, you'll shim those areas later so the board doesn't bow when you tighten it down.

Step 4

Drill Pilot Marks and Anchor Holes

With your ledger board pre-drilled (most come with holes already spaced out, or you can drill your own), hold it back up at your marked, level position and use a small carbide-tip bit to lightly mark the stone through each pre-drilled hole. You're not drilling deep, just scoring the surface enough to know exactly where each hole needs to go.

Remove the ledger, then switch to a larger carbide masonry bit sized for your lag shields and drill into each marked point. Because you used the ledger itself as a template, every hole in the stone will line up with the holes in the board.

Step 5

Install the Lag Shields and Secure the Ledger

Lag shields are soft metal anchors that split apart and wedge inside the drilled hole as a lag screw is driven in, locking the anchor, and eventually the ledger, firmly to the masonry. Tap or slip a lag shield into each hole you drilled.

Now hold the ledger back in place, push a lag screw with a washer through each pre-drilled hole, and start threading it into the anchor by hand. Once every screw is started, double-check the ledger is still level, then snug everything down with a socket wrench.

At the spots where the board doesn't fully contact the stone, insert a wood shim before tightening that lag screw. Tightening against the shim, rather than into open air, keeps the ledger from bowing and keeps the whole board rock solid.

Step 6

Hang the Mantel

Drill four or five pilot holes along the top of the mantel where it will rest on the ledger, then lift the mantel into place and center it.

Through those pilot holes, drive 8-penny finish nails down into the top of the ledger board. This locks the mantel to the ledger and, in turn, to the stone.

Step 7

Finish the Nail Holes

Countersink the finish nails just below the surface of the wood, then fill each hole with wood putty that matches your mantel's finish. Once it's dry and lightly sanded, the attachment points disappear completely.