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French cleat for fireplace mantel shelf?

JohnRyan's picture

Ok, so, I'm new at this.  I am building a mantel for my fireplace.  It is just a shelf with two corbels for support...so, no wood travelling all the way down the sides of the fireplace opening...it's just the shelf with corbels.  I am thinking about fastening the corbels to the fireplace brickwork using a french cleat for each corbel.  My mantel shelf is about 5ft long and 7 inches deep, and 2 inches thick.  The corbels are about 4inches deep (two 2inch pieces attached together for the depth) and 5inches wide and perhaps 6 inches high.  I am going to attach it to the red clay brick of the fireplace, which are full bricks (not a decorative facade)  I'm thinking that I would drill the wall part of the cleat to the brick using tapcon screws into the mortar.  The part of the cleat on the corbels I want to kind of hide inside of the corbel (not sure how I'm going to do that yet).


Now, I've read a bit on french cleats, it looks like I could use 3/4 inch stock and cut either 45 degrees or 30/60 kind of thing.  My problem is that the context in which I read about french cleats is almost always with cabinets rather than shelves...or in my case these corbels.  It feels like if I do this, that the shelf (and corbels) will tip forward out of the cleat because it doesn't have the kind of height that a cabinet has for leverage.


Also, I've read about rabbited or "straight" cleats where rather than cut an angle, use sort of intersecting "L"s...which seems to be a good solution for uneven walls...although the brick of my fireplace...even though it's not flat...does look to be quite straight as far as that goes.


Any thoughts or insight for me on this? Before I start cutting...will the angled french cleats work for me? Thanks.

WillGeorge's picture

(post #121234, reply #1 of 26)

All that a French Cleat needs is a good support and something close to a good match.


Sort of like a Husband and Wife. Not a perfect match but will join if the mood is right!


Make the wall cleat sturdy and whatever hangs off will be OK!


Edited 12/28/2008 8:15 am by WillGeorge

Have a great day.. Life is wonderful even if you are having a bad day!

JohnRyan's picture

(post #121234, reply #4 of 26)

OK...thanks so much for the input.  I'll let 'er rip and see how it goes.

hammer1's picture

(post #121234, reply #2 of 26)

I used French cleats to mount this mantle shelf. I had to fit to rock. I added a perimeter piece to the back of the corbels to allow some fitting and provide a space for the cleat. This is large and heavy and so were my attachment cleats. Set your screws or bolts into the mortar joint.

Beat it to fit / Paint it to match

Beat it to fit / Paint it to match

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PeterDurand's picture

(post #121234, reply #3 of 26)

Very nice.

 


Better life through Zoodles and poutine...

JohnRyan's picture

(post #121234, reply #5 of 26)

Hey Hammer1,   whoa! That thing is huge!  Mine is certainly not as "finished" as that. Phew.  I'll try the cleat and see how it goes.  One thing I noticed...and part of what I think might be my issue (and by the sounds of it...it should work)...but, your corbels are quite long compared to mine. I was doing corbels that would be about 6 inches high (from top to bottom)...and with the shelf overhang...which will end up being something like 3 inches, I am feeling like the thing is going to tip forward.


Thanks for the feedback and the photo.

joinerswork's picture

(post #121234, reply #6 of 26)

John,


Are you married to attaching the cleat behind the corbels?  If the shelf is thick enough, you can attach it to the cleat.


Ray

JohnRyan's picture

(post #121234, reply #9 of 26)

Ray, thanks for the reply. Ya, I was thinking that I might see about doing something like that. The shelf is 2" thick...walnut. Perhaps I should use a piece of walnut as a sort of back plate and make it bigger than what I'm imagining.

hammer1's picture

(post #121234, reply #7 of 26)

On small brackets, you can use a few different types of mounting hardware. There are metal keyhole plates that are let into the back of the bracket. Some corbels come with them. Also Z clips, which are a metal french cleat, as well as other interlocking mounting fixtures. A shop made french cleat can be the most versatile. As long as the bevels mate fully, I wouldn't worry about the shelf tipping out, I would worry about something,... like your head, knocking it up and off, ha ha. Better have a way to glue or pin so that can't happen.

Beat it to fit / Paint it to match

Beat it to fit / Paint it to match

JohnRyan's picture

(post #121234, reply #10 of 26)

Hammer1...yessss...exactly...that's what I dread...the thing tipping forward or getting knocked off.  Are you supposed to glue a french cleat?  If so, I didn't know that.


I was thinking...another option.  I was thinking that I would make a corbel with two pieces (walnut)...the pieces are 2" thick.  I was thinking that I would attach them together with glue and thickish dowels...(homemade on my router no doubt hehe).  So, shape them up the way I want and dry fit them...then...take the back of one and bolt it to the brick...then glue the other onto it...and glue and pin the shelf as well.  The problemo I see with this approach is that I'm not assembling and finishing it and then attaching it...rather...I'd have to assemble and finish some of it on the wall. Ack...no...I'm not doing that.  I'll check out the z-clips and other hardware too before I make a decision.

hammer1's picture

(post #121234, reply #13 of 26)

Hi John, normally you don't glue the mating pieces of a french cleat, the weight of the object holds it in place. However, something like your mantle shelf could get knocked. It might be a good idea to eliminate that possibility. I think I would try to get a screw in where it doesn't show.

You could always cut a slot in the back of the corbel to allow a cleat to fit. When I did my monstrosity, I hung the corbels first. Got them fitted, level and plumb. I carefully measured, removed them and added the raised panel section that went between. The shelf section was then attached. There was enough thickness in the "molding box" to add some fasteners through to the rock, the top went on last. I pre-finished all of it before installation.

I worked out the design with the owner. Started with a bunch of mantle pictures and picked out elements that they liked. I combined them to coordinate with other architectural details in the house, lots of arched windows. I drew the plan out to full size and cut it out with scissors. I took the drawing over and tried it on the fireplace. Good thing I did. The first attempt was way off in terms of scale. This was a big place. Not exactly my taste but I don't live there. Extra time planning and thinking it through usually makes a difference. A small design change may make attaching a little easier. Something like a crown molding supporting the shelf will provide a pocket to make some attachments. It all depends on what you want for a design.

Beat it to fit / Paint it to match

Beat it to fit / Paint it to match

JohnRyan's picture

(post #121234, reply #14 of 26)

I like the idea of cutting a slot into the back of the corbel for this.  I also like the idea of drawing the whole thing up to scale and then checking it against the fireplace.


Ok..so, I mocked up some implementation options in paintbrush on my computer. It's not CAD...but hey, it is pretty close in terms of dimension. In the attached .jpg, there are 3 options.


The views are from the side, so the brick would be on the left. The french cleats are in red and masonry screws or bolts in grey.  These are just the rough blocks..I have plans to make some custom moldings to wrap around too and stuff...I got some router bits in my stocking from Santa...gotta put them to good use!!


Option A: Here I was thinking that I cut the cleat out of the walnut back portion of the corbel...leaving some room at the bottom to be able to fit it over.  Take the piece I cut out and secure it to the wall. Totally finish the piece and hang it up.  The cleat would be (presumably) flush with the back of the corbel...so I could see it staying in place..and, if the gap at the bottom was right...it might actually be hard to knock it off.  The problem with this it seems to me is that the cleat isn't going to actually fit properly because when I band saw it out...the width of the saw blade is going to perhaps cause a problemo.


Option B: Make and fit a cleat onto the back, slide the top shelf back which would "bring the corbels out a bit"..then hide the cleat with trim (which looks like I'd have to do in all cases anyway). 


Option C: Make a notch (as suggested thank you) in the back of the corbel...then put the cleat into that. I like this because I can cut the notch and account for the saw blade gap so the cleat is flush with the back for mounting to the wall...and the cleat should fit itself perfectly.


So, waddya think?

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hammer1's picture

(post #121234, reply #15 of 26)

I used something similar to option C. You don't have to make the bevel 45. 30 is plenty, easier to seat and you don't need as much extra space to get it in there.

I have an extra pair of keyhole plates if you want them. You just have to get the mounting screws evenly placed and solid. The plates are let in flush on the back of the bracket. Click on my name and send me your address.

Beat it to fit / Paint it to match

Beat it to fit / Paint it to match

JohnRyan's picture

(post #121234, reply #17 of 26)

Hammer1...really? You'll send me some brackets? LOL..cool...okay...I'll send you my address.

hammer1's picture

(post #121234, reply #18 of 26)

Plates are in the mail, John. Hope they are of use to you.

Beat it to fit / Paint it to match

Beat it to fit / Paint it to match

WillGeorge's picture

(post #121234, reply #19 of 26)

Beat it to fit / Paint it to match should be changed to ..


Beat it to fit / Fill with Bondo/ Paint it to match

Have a great day.. Life is wonderful even if you are having a bad day!

hammer1's picture

(post #121234, reply #20 of 26)

Fill with Bondo?? That's an extra step, Will. My prices would have to go up.

Beat it to fit / Paint it to match

Beat it to fit / Paint it to match

davcefai's picture

(post #121234, reply #21 of 26)

I keep seeing references to "Bondo".

Would this be similar to "Bondapaste", a polyester filler where you add a pea sized blob of (pink) hardener to a golfball of grey paste. Hardens quickly, beautifully sandable?

MikeHennessy's picture

(post #121234, reply #22 of 26)

Probably -- Bondo is a trade name for a resin-hardened auto body filler used in sheet metal repair work -- and it's been appropriated by carpenters as a wood filler as well.


Mike Hennessy
Pittsburgh, PA

Mike Hennessy
Pittsburgh, PA
Everything fits, until you put glue on it.

JohnRyan's picture

(post #121234, reply #23 of 26)

Yep, Mike's correct. My first jalopy was a "Bondo Buggy". Didn't know it was used on wood too.  I know my pool table has 3 peices of 1" slate...leveled and then the seams between the peices are bondo'ed before the felt goes on...which I also thought was kind of surprising....but hey...it "seams" to work....hehe (ok boooo).

davcefai's picture

(post #121234, reply #24 of 26)

It's great stuff. I use it and also some of its kindred. There's "Isopon" which is an epoxy resin which sets harder and can be drilled and tapped.

Then there's "Chemical Metal" which is like Isopon but I believe has better adhesive properties. And all the others like Araldite and Plumber's Mait.

The world is a better place with Epoxies.

heartwould's picture

(post #121234, reply #16 of 26)

Nicely done!

resistorhead's picture

(post #121234, reply #8 of 26)

I'm just finishing up a mantel for my daughter and am going to use a cleat for the first time. I am also a little apprehensive. I cut the cleat out of 3/4" plywood at a 45 degree angle. I will attach to drywall with brick under it. I'm going to attach in three locations. I think it will be fine as long as the cleat is securely and tightly attached. I don't know how well the tapcon screws will work. The mortar may be too crumbly. I'm going to use anchors in the mortar and screw into those. I'll let you know how it goes. Hope to install this weekend.

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JohnRyan's picture

(post #121234, reply #11 of 26)

Nice....I'll look forward to how you make out there.


My problem, it seems, is I don't have a "box" in which to hide the cleat.  Perhaps I need to re-jig my design a bit to make life easier on myself.

MikeHennessy's picture

(post #121234, reply #12 of 26)

Just an FYI -- When I'm dealing with old (e.g., soft) or crumbly mortar, I don't hesitate to drill and anchor into the brick instead. It's not really a big deal if you use a good SDS drill and bit, and you end up with a more reliable connection.


Mike Hennessy
Pittsburgh, PA


 

Mike Hennessy
Pittsburgh, PA
Everything fits, until you put glue on it.

resistorhead's picture

(post #121234, reply #25 of 26)

Update - I test fit the mantel for my daughter's fireplace using the cleat. I used lead anchors set directly into the brick. It looked great. I am going to silicone a couple of small, thin strips of wood to hold the cleats together. That will keep the mantel from getting knocked off and make it easy to take apart if I ever need to. I used 3/4" plywood for the cleat but I think next time I will make it thicker for better support.

Eddie

JohnRyan's picture

(post #121234, reply #26 of 26)

Thanks for the update Resistorhead.  So, I guess you feel like there is some potential that it could get knocked off the cleat(s) then?  Hammer1 sent me some plates to use to fasten it as an option.  I'm thinking I either will use the plates or make a cleat that is the full length of the mantel.  I can't imagine that if I used a "full length" cleat that it would be able to be bumped off...I mean it seems it would have to be a pretty hard bump.  I am kind of dying to try out me first french cleat tho'.  Maybe I'll do the cleat first and if unhappy, I'll just change it.  I need to finish wiring up my garage first.  I'm adding a subpanel in there...and stuck on some "electrical" questions I have.  Maybe I'll post something.