How to attach Corbels?

[mschrank]

Part of my ongoing kitchen remodel involves using some corbels (fancy word for brackets) attached to a half wall to support a concrete countertop. After seeing the high price for pre-made corbels, I decided I will make my own out of 8/4 hard maple (besides saving money, I can style them like I want).

Question is: How do I attach these to the wall? They are more than decorative, and have to be stout enough to support the heavy countertop and the weight of someone leaning on it.

I could drive lag bolts through the face into the wall studs, but then I'd have a huge hole to plug on a curved surface.

Anyone know how this is done?

[ChrisD]

Mike,
I would think these bed rail fasteners should work: http://www.woodcraft.com/family.aspx?FamilyID=3269

How much overhang is being supported by the corbels?

[mschrank]

Mike,
I would think these bed rail fasteners should work: http://www.woodcraft.com/family.aspx?FamilyID=3269

How much overhang is being supported by the corbels?

That's an idea...though they would allow a bit of side to side play. I suppose the countertop would hold it in place (I'm assuming the installer will use some type of epoxy to secure the counter to the cabinets and corbels), but I think I want something more secure.

There will be about 10-11" of overhang.

[LCHIEN]

Mike,
I would think these bed rail fasteners should work: http://www.woodcraft.com/family.aspx?FamilyID=3269

How much overhang is being supported by the corbels?

Personally I think that's a misapplication of the bed rail devices.
In a bed, the rails are supported at both ends so all the screws are sharing the full load in shear mode.

In a countertop support, the hardware will be in a cantilever mode, where the load is taken primarily by the top screw in tensile mode. The screw probably won't fail before it pulls out - its's not that big a screw.

I'm more in favor of the 1/4" lag screw approach. I've been trying to think of a way - here's one I've done:
Use a Corbel with a baseplate. The base plate goes between the wall and the rear of the corbel. If the corbel is 1" wide, then a baseplate of 3" wide would be OK. Basically a plate of 1-by material 3" wide., you can router an ogee edge on the sides and bottom (to top will be cut flush with the top of the corbel) for looks (It'll be under the countertop so won't show much anyway).

So you put 2 lag bolts from the back of the baseplate into the rear edge of the corbel. You have to drill a countersink hole for the head so the back of the plate is flush. Now put a 1/4" dia hole in the front of the plate along side the corbel so its accessible from the front. Two on one side or two, one on either side depending upon what we're going to screw to in the wall. (if its a vertical stud, two on one side is necessary)
Anway, countersink the front side 3/8" to 1/2" to seat the head of the lag bolt below and then when you are done you can cover the hole with a plug.

Now you should have corbels firmly attached to the wall with at least 1/4" lag bolts. and no holes in the contoured face of the corbel.

[JR]

How about something like this?

Drill the hole and form the plug for the lag bolt before shaping the corbel. Insert the plug while shaping the corbel. Pop out the plug for installation of the lag bolt. Insert the plug and finish.

Just a thought.

JR

[LarryG]

I've scratched my head over any number of concealed-fastener details in my time. There's almost never a way to do it that doesn't involve lots of fooling around. "Lots" being the operative word.

In this case, I'd make up some steel angle L- brackets and bolt them to the wall to support the weight of the countertop. Then slot the backsides of the corbels to fit over the legs of the angles. Since the corbels are now purely decorative, that can be attached with small, easily-concealed screws or nails.

[ChrisD]

Good ideas from Loring and JR. I do think 10" would be too much for a bed rail fastener to support.

I also thought about the baseplate idea, having seen it from a WW plan for a pergola, which used that method to attach brackets between the posts and the outermost beams, but wasnt' sure if you wanted a "cleaner" look. Not that I think there's anything "messy" about a baseplate! Like Loring said, it's not in a very conspicuous spot.

[crokett]

Mike,

For the installation my research in prep for pouring my counters says that precast concrete counters are installed over 3/4 ply that is screwed to the top of the cabinets.

As far as the corbels go, lag screws through the back of a baseplate would be the strongest and easiest. If you wanted to conceal all the screws with no plugs you could use a baseplated with a keyed feature to slot the corbel into. This would be a bit of work but it would be an interesting build. I like interesting.

Make your base plate.

Make your corbel. Make it 3/4" taller than the base plate and 3/4 longer in the horizontal. Cut a 3/4" wide section off the back so that you leave 3/4" at the top. Cut a dado 1/4" deep and at least 1/2" wide on both faces running vertically at least 1/2" from the back edge.

Rabbett 2 pieces that are the same length as your corbel is tall. The rabett width should match the how far your dado is from the edge of the corbel and depth should match the dado depth. Fix these to the baseplate and use the corbel as a spacer (centered on the baseplate). Attach the baseplate to the wall with the lag screws installed between the 2 rabbetted pieces. Slide the corbel down from the top. Put a screw down through the top of the corbel into the baseplate. Now unless that screw shears and the wood fails the counter will stay up.

[jrnewhall]

Why not attach it like you would a mantel? Build it hollow near the top, the hollow being the size of a block that you bolt to the wall. Slide the corbel onto the block and put a screw through the top to attach the two. The counter will cover the screw.

~JRN

[mschrank]

As usual, a great bunch of responses. Geez, I'm finding it's easier to not even think through a problem...just post it here and voila! I actually enjoy problem solving though...

I like the simplicity of JR's and jrnewhall's suggestions. Larry came up with a idea I would never have thought of, but since I'm not a metalworker, I'll probably rule that out. I was already thinking somewhat along the lines of Loring's suggestion (scary...I'm thinking like an engineer ). But I would like to avoid the baseplate, as it will be mounted right where a stile is located in some panels I'm also building. And David's suggestion...well, let me read through it a fourth time and get back to you....right off it looks like too many cuts (i.e., I'd screw one up), but I think it would be rock solid.

The whole kitchen project should be completed within the next few weeks, so I'll post pics and let you know what I ended up doing.

Thanks all...and I'm still open to any more ideas.

[crokett]

Mike,

It is actually pretty simple. What might be faster (and an excuse for a new tool or a new router bit anyway) would be a sliding dovetail joint. Same idea but I think that would be simpler.

[mschrank]

Mike,

It is actually pretty simple. What might be faster (and an excuse for a new tool or a new router bit anyway) would be a sliding dovetail joint. Same idea but I think that would be simpler.

Hey, I like that idea! And now I understand your first suggestion better

As far as an excuse to buy new tools...that was the actually the point of this whole kitchen remodel (in my mind ). See...I got bids from some contractors. These shocked the wife (as intended). I then point out that we can do it for at least $20,000 less (it's actually more than just a kitchen remodel, a bathroom and new hardwood flooring throughout the house got thrown in). So I figure even if I buy $5,000 in new toys, we're still way ahead.

[crokett]

Mike I was bored last night so I did this. Very rough but...
Top view. Blue is the baseplate, yellow is the corbel and orange is the brackets. Looking at it from the side this is all flush on top of course. Probably way over engineered but you have fun making them and you know the counter is never going to fall.