Advice for a New Mantle Piece

[ken gibbs]

I have been tasked to build a mantle piece and will use an old pice of sugar maple that I have had for 14 years. This 80 lb. chunk is about 7 1/2' long and three inches think. Stonework was just layed on backerboard up about five feet above the hearth at the fireplace surround. The stone mason did not morter in supports for the mantle so I have to cut a rabbit in the maple piece to sit the mantle on the top of the stone facade that extends from the wall 3 1/8 inches. My design problem is how to add supports to both sides of the mantle piece which is about 11 " wide and is flat on top but I have left the original knots and bark on the bottom side. I don't know of any lag bolts that would be strong enough to handle this puppy. So my options are:
1, Add corbills to each side and try to catch studs that would yield the support I need.
2. Or, try to produce some pillasters to each side of the surround with built in corbills over the stone. Not my favorite choice but it would give the needed load bearing support.
3. Catch up with the dude that layed the stone and beat him up. Then sub out ths portion of this job.

Any suggestions about bracing that would look good for this very rustic application? Thanks.

[Rick Pettit]

A friend of mine just put one up exactly like you are describing. He used red head anchors in to a mortar joint and the put 3/4 inch conduit over the red head. He then drilled holes in the back of the mantle and slid it on the conduit. Used a bunch of construction adhesive. Seems to be holding the mantle up well.

[Steve Kohn]

Is there any chance to pull the stone off the backerboard to give yourself a slot to mount the mantle to? Then you can drive a couple of long lag bolts into the supporting studs behind the backerboard. Once the lags are into the studs, you can cut off the heads and drill corresponding holes into the mantle. Slide the mantle onto the lags with a bit of epoxy.

[Mark Bolton]

A friend of mine just put one up exactly like you are describing. He used red head anchors in to a mortar joint and the put 3/4 inch conduit over the red head. He then drilled holes in the back of the mantle and slid it on the conduit. Used a bunch of construction adhesive. Seems to be holding the mantle up well.

This was the option I would suggest "if" you can open up the wall and gain access to the studs. I would not be too comfortable trusting the mantle to a lag in the stud face to not sag or pull out over time. The bigger the lag, the less stud there will be there to hold it. The way we have done these is to fabricate a steel plate or yoke that lags/bolts into the sides of the stud with a 1" steel pipe projecting out to be embedded into the mantle. The plate/yoke allows you to bear more of the weight on more of the stud. Thats a lot of leverage on that connection and as stupid as it may sound the scenario you have to think of is one day someone is trying to hang a wreath above the mantle and they step, or stand, on the mantle and it either tears off the wall or bends at best.

If you dont do any metal fabrication any shop could fab you either a flange or a yoke that would allow you to attach to the sides of the stud rather than lagging into the face. That would all be dependent on your ability to open the wall up at the mantle connection point.

There are other options, metal bracket as opposed to a corbel where you could simply drill through a stone and using a small standoff (piece of tubing) as a shim, plumb the brackets, screwing them to the studs. Brackets on top of the mantle, and so on. But many of them will likely look like what they are, a patch job to recover from poor planning.

These are often the situations we get put in, "Hey I got all this done, now can you make it look right". Its never fun.

Mark