Mantel over brick fireplace

Old 11-09-02, 05:49 AM
Visiting Guest
Posts: n/a
Mantel over brick fireplace

I plan to install an oak mantel and marble surround over my brick fireplace. The brick surface is very uneven. An earlier post had a cement board answer for installing the marble tiles. How do I prep for the mantel?
Old 11-18-02, 05:42 AM
Join Date: Aug 2000
Location: USA
Posts: 15,047
Upvotes: 0
Received 1 Upvote on 1 Post
Installing a mantel

Fire prevention is always a concern when installing a wood mantel around an open fireplace. Before ordering or installing any mantel, consider the following requirements:

According to the National Fire Protec-tion Association--the agency that writes fire-safety codes--there must be at least 6 in. between the sides and top of the firebox opening and any wood that projects up to 1 1/2 in. from the face of the fireplace. Any wood that projects more than 1 1/2 in. (such as the mantel shelf) must be at least 12 in. from the opening.

Note: Every town has the power to modify the national building and fire-safety codes; be sure to contact the local building department for specific codes requirements in your area.

I started this project by first covering the old brick around the firebox opening with tiles made of Vermont slate. However, you can skip this step if the existing brick or stone facing on your fireplace is attractive and in good condition.

Originally I wanted to cover the brick with thick slabs of polished granite. That is, until I discovered it was going to cost $600 to $700. I also considered marble and glazed ceramic tile before choosing the 3/8-in.-thick slate for its natural beauty and texture. Two boxes of precut slate tiles (20 sq. ft. total) cost $26 at a local home center. I also picked up some thinset mortar ($13), gray nonsanded grout ($10) and a bottle of matte-finish masonry sealer ($14).

Note that it takes two days to complete the tiling because the mortar must cure overnight before you can grout the joints. Slate tiles come precut into squares and rectangles of various sizes. Chances are, though, you'll have to cut a few pieces to fit. You can cut slate with a masonry blade (either carbide-tipped or abrasive) in a portable circular saw, or you can rent a wet saw ($60 per day) that will easily slice through the rock-hard stone. But don't try to use a manual score-and-snap tile cutter; slate is simply too hard.

Start by brushing a coat of clear sealer onto the slate tiles. Sealing them at this stage before they're installed will make it much easier to clean off any mortar or grout from the surface. Mix up some thinset mortar and let it rest, or slake, for 10 minutes. Next, use a notched trowel to spread the mortar onto the brick ends along the right and left edges of the firebox opening. Also spread mortar onto the back sides of the slate tiles, a technique that's known as back-buttering. Press the tiles into place (step 1, see image above) and give each one a few sharp raps with a rubber mallet. For spacers between the slate tiles, I used two strips of thin cardboard, which produced 3/32-in.-wide joints.

Once the ends of the bricks are tiled, spread mortar onto the brick facing and set those slate tiles into place. Again, use the mallet to tap the slate firmly into the mortar (step 2).

Use a rubber mallet to firmly set the slate into the mortar. Thin cardboard strips act as tile spacers. ( Geoffrey Gross)

After applying slate to the left and right sides of the firebox opening, trowel mortar onto the brick face above the opening.

Before setting the horizontal row of tiles on the brick above the opening, erect a support shelf to prevent the tiles from sliding down. Cut a 1x3 to fit across the width of the opening, then wedge it in place with two vertical 1x3s and two shims. Now back-butter the slate tiles and set them into the mortar over the opening (step 3).

Press the tiles into the thinset mortar above the firebox. The 1x3 support shelf wedged in the opening helps keep the tiles from sliding down. ( Geoffrey Gross)

Let the mortar cure overnight, then remove the spacers and fill the joints with grout. To speed up this step, I filled a sandwich bag with grout, snipped off one corner and squeezed the grout directly into the joints (step 4).

It's in the bag: Fill a plastic bag with grout, then snip off one corner and squeeze the grout into the joints. ( Geoffrey Gross)

Remove any excess grout with a plastic putty knife or wood shim (a metal tool will scratch the slate). Wait 20 minutes, then wipe the slate clean with a wet sponge (step 5).

Wait about 20 minutes, then use a wet sponge to wipe off the excess grout from the surface of the slate. ( Geoffrey Gross)

After 45 minutes, buff the slate with a dry cotton cloth

As mentioned earlier, it only takes a couple of hours to install the mantel. You can save yourself some time and trouble by painting or staining it the day before.

Start the installation by setting the mantel into place and centering it on the firebox. Mark short pencil lines onto the wall along the top and sides of the mantel. Move the mantel out of the way, measure down from the horizontal line the thickness of the mantel top plus 1/8 in. and draw a level line on the wall. (The top of my mantel was 1 1/2 in. thick, so I measured down 1 5/8 in. from the pencil mark.) Repeat the process for the two vertical lines at each leg of the mantel.

Cut a 2x3 or 2x4 about 3 ft. long and screw it to the wall above the fireplace (step 6).

Screw a 2x3 cleat to the wall above the fireplace. Position it so that the mantel will just slip over it. ( Geoffrey Gross)

Be sure that the top edge of this cleat sits just below the level line you marked earlier. Cut two 1x1 cleats about 1 2 in. long each and screw them to the wall on either side of the fireplace. Mark the positions of the cleats with strips of tape (step 7).

Mark the cleats' positions with tape to indicate where to drive in the screws when attaching the mantel. ( Geoffrey Gross)

Stand the mantel on the hearth, tilt it forward and press it to the wall (step 8).
Tilt the mantelpiece into place, making sure it slips over all three cleats and fits tight against the wall. (photos: Geoffrey Gross)

Check to be sure that it slides over all three cleats and fits tight to the wall. Attach the mantel to the top cleat with 2 1/2-in. screws (step 9).

Drill a counterbore hole, then drive a 2 1/2-in. screw through the mantel shelf and into the cleat (photo: Geoffrey Gross)

Use trimhead screws to attach the legs to the vertical cleats; their tiny heads will be undetectable once painted to match the mantel. You could nail the mantel in place, but screws make it much easier to remove the mantel if it ever needs refinishing or repairs.

As I stood back to admire my new mantel I realized that it looked a little plain. So, I ordered three sunburst-pattern appliquás ($50) from Readybuilt. I put a blob of silicone adhesive onto the back of each one and nailed them to the mantel. The large one is centered on the mantel's fascia. The two smaller ones are placed on the blocks above the fluted columns (step 10).

Install each of the sunburst-pattern appliquás with silicone adhesive and 3/4-in. wire brads. (photo: Geoffrey Gross)

The appliquás add a little extra style and interest to the mantel and to the room, which was the goal of this project in the first place.

Easy Mantel Makeover
Installing a ready-made mantel over a brick fireplace.
by Joseph Truini
Weekend Projects
This Old House Online
Retrieved 18 November 2002,00.html
Old 11-19-02, 04:57 AM
Join Date: Oct 2001
Location: USA
Posts: 959
Received 9 Upvotes on 9 Posts
I think you should talk to the local building inspector. I am in the planning stages of refacing my brick fireplace. I am using oak flooring for all but the area around the firebox and am putting on an oak mantel. I was planning on stripping the brick with wood furring and attaching the oak to that.

I met with the local inspector and was told I cannot have combustibles (including the mantel) within 2" of the masonry, anywhere. The way I am resolving it is to use 2-1/2" metal studs covered with plywood to nail the oak to.

In reading the code (UBC), I think the local inspector is correct; however, I may still talk to the State inspector. After all, how many thousands of wood mantels do you see attached directly to a masonry wall?

Old 11-19-02, 03:39 PM
Join Date: Aug 2000
Location: USA
Posts: 15,047
Upvotes: 0
Received 1 Upvote on 1 Post
Building Codes

Note: Every town has the power to modify the national building and fire-safety codes; be sure to contact the local building department for specific codes requirements in your area.

Thread Tools
Search this Thread
Ask a Question
Question Title: