# French cleat limits? - front to back?



## jaykal001 (Nov 27, 2013)

Hi all,
I'm putting together a rustic mantel for our fireplace where there is currently nothing, and wanted to know if a french cleat would work in the case for mounting. (First and foremost, we have no kids, i'm not worried about people or animals swinging from it, just being structurally capable.)

My mantel size of choice is going to be close to 6 feet wide, 3.5" thick and 7-8" front to back. I'm wondering if a cleat on the 3.5" face is going to be be able to support something that protrudes from the wall as much as 8". Diagram of side view attached. I'm thinking this will have a larger 'leverage' type effect than hanging something taller like a cabinet. Not sure sure if it'll really matter for the material of the cleat, but not opposed to using a small board of oak/maple if the strength is needed.

From a pure style aspect, would love not to use some sort of supporting corbel if not needed.
Thanks for your thoughts,
Jay


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## Steve Neul (Sep 2, 2011)

For that application I think two rabbeted pieces would work better. You don't really have enough vertical height of the mantle for a french cleat to work.


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## Chris Curl (Jan 1, 2013)

My understanding is that a French Cleat is better suited for applications where the cleat is near the top of the piece, and most of the weight is below the cleat.

In other words, a French Cleat is designed to carry the weight vertically, not horizontally.

This application looks like most of the weight is horizontal to the cleat, i. e., at the same height or even above the cleat.

So I think you are correct to be concerned.


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## FrankC (Aug 24, 2012)

You really need some floating shelf type brackets to hang the mantle. Something like what is shown here:
http://www.rockler.com/blind-shelf-supports?sid=AF078


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## jaykal001 (Nov 27, 2013)

@FrankC
I'm not saying your right or wrong, but I'm wondering how that'd be better.
You still have a single row/line of screws attaching to the wall/brick and all the same leverage problems that i'm concerned about.

I could see something like this http://www.mulrooneyjoinery.com/wp-.../ash-70mm-mantel-with-hermitage-corbels-3.jpg
- where the corbels (spelling?) support some of the way to reduce that torque - but the blind ones seem to be a similar problem.

I'd love the idea of a pure floating mantel, but certainly understand it may not be feasible.
(I also thought as a second option, is i could go the route of something like an 8x8 hollow box, then i could probably get away with the cleat


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## Steve Neul (Sep 2, 2011)

What would be better is to chisel out a few bricks and mortar in some wooden blocks sticking out from the wall to slip the mantle over. If the mantle had been planned for when the fireplace was being built this is a common way to do it.


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## Chris Curl (Jan 1, 2013)

I watch alot of those "vintage restore" or "stone house revival" type of shows, and they often use things like what Frank linked to for mantels.

The ones they use on the show are big versions of those mothers.


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## jaykal001 (Nov 27, 2013)

Any thoughts one something along the lines of a sliding dovetail?
If i ran it vertically, and put a stop in it so it wasn't visible from the top, I could use a pretty substantial width board. At that point I could probably get close to 3" of vertical mounting.


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## Toolman50 (Mar 22, 2015)

Is your mantle being made of solid wood or will it be hollow?
Since you show the thickness to be 3 1/2", you have plenty of room to mortise out the back edge and fit it ove a board attached to the wall.


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## Jim Frye (Aug 24, 2016)

I did a "floating mantel shelf" some years ago on the face of a marble rock fireplace. The ledger board was bolted to the fireplace with two threaded inserts set in mortar joints and the shelf was screwed to the ledger board with two screws on the underside of the shelf. The shelf itself was a "torque box" that slid over the ledger board, thus hiding it completely. Very strong setup. French cleats are meant to support the weight in a downward, or vertical force. The mantle shelf might put more outward strain on the joinery. By the way, my shelf was carved to fit tightly up against the rock face and there was no chiseling of the marble rocks to get things mounted. I used Bondo on the back side of the ledger board to fit it snugly up against the rocks. I put plastic wrap on the rocks and pressed the ledger board up against the rocks while it was still soft to get the fit without laborious carving of the Bondo. The Bondo was done in four 6 inch "lifts", two on each end. The top and bottom of the mantle shelf was 3/4" oak plywood with the core framing of 1x3 pine. The ledger board was made from two layers of 1x3 strips of 3/4" plywood glued and screwed together. The shelf was 4 1/2" thick, nearly 10" deep, and about 6 feet long. Here's a couple of pics of things. 
http://www.woodworkingtalk.com/memb...orking-projects/38841-fireplace-mantle-mount/
http://www.woodworkingtalk.com/memb...orking-projects/38833-fireplace-mantle-shelf/


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## FrankC (Aug 24, 2012)

Chris Curl said:


> I watch alot of those "vintage restore" or "stone house revival" type of shows, and they often use things like what Frank linked to for mantels.
> 
> The ones they use on the show are big versions of those mothers.


I used the Rockler hardware as an example, of course they would be beefier, it was just food for thought based on the fact that I have hung a few mantles in my time.


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## Quickstep (Apr 10, 2012)

Is your wood mantle shelf attaching to Brick?

How about something like this?


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## Jim Frye (Aug 24, 2016)

Just caught my technical error in my post from yesterday. The mantle shelf was a "torsion box", not a "torque box". The torsion box has all sides enclosed, while a torque box has one or two sides open. Sorry for any confusion.


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