Support for kitchen peninsula 15 inch granite countertop overhang

7 years ago

Hi everyone, I am having 3 cm granite countertops installed in about three weeks. We have a peninsula that will also serve as a breakfast area. The granite there will have 38 cm (15 inches) of overhang over a span of 135 cm (51 inches).

I'm a little nervous because here in Germany, kitchens don't usually have this type of overhang, and most professionals we talk to have never done it before (most people here usually want less than 10 inches of overhang for their bars. We feel like we have plenty of room and would like lots of space for the kids to sit, eat, do homework, etc.

Our kitchen installers only planned for 12 inches of overhang (which they were going to leave unsupported), we told them during installation that we had requested 15, and that we understood that it would have to be supported somehow. They only suggested adding a single leg under one corner (on the left side), since the opposite side can be supported at the wall (it's a peninsula). Their suggestion made me nervous, and makes me wonder if a single leg is enough.

I am getting ready to suggest that we do two columns with stretcher bars (like a table), attached to the peninsula. But, since this is my own idea, i am still wondering if it will be enough to be 100% safe.

I am including two photos, one of the kitchen island view, and the second of the columns/apron setup I'm thinking about.

Could someone weigh in as to whether the setup is viable and safe? We have small children (under 5) and need this to be super safe.

Do bear in mind that this is Germany. Most kitchen places have not even heard of invisible steel supports or anything elaborate like that. This is why I thought of legs/apron for this, since any carpenter can produce them readily.

The columns would be about 11 cm square (4 5/16 inch). In my thinking the apron would consist of 8 x 5 cm lumber (3 1/8 x 2 inches). The whole thing would be attached to the peninsula.

Featured Answer

User

7 years ago

last modified: 7 years ago

I would add additional cross pieces to the stretchers, in an H pattern. Long runs of wood tend to become warped with humidity changes. Cross bracing will offer addition support and help to prevent that.

There comes a point when the wood length is just too long and will need a 3rd leg in the middle. 8’ approaches that. It depends on the climate and engineering. Steel is stronger, more stable, and can support better, with the wood stretcher aprons only being decorative. On long or deep overhangs, it is a far better choice for the structural components, leaving the wood as a facade.

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Comments (11)

Kathy Drakos Cattano
7 years ago
I have worked in a natural stone distribution center and we are good friends with the granite fabricators. Speaking only to natural stone, most would recommend for the stone support to add a corbel or hidden metal brace every 24” to be located under the stone countertop where it meets the base cabinet.. Hope this makes sense!
edanz
Original Author
7 years ago
Hmmm... yes, that is what I'm afraid of. I may have to order the hidden metal braces from the US.

I also should make a pretty important correction: The granite will have 38 cm (15 inches) of overhang over a span of 210 cm (82 1/2 inches). That's over six feet!
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PRO
Joseph Corlett, LLC
7 years ago
The pictured legs and stretchers will adequately support a 3cm 15" natural stone cantilever.
Suzanne
7 years ago
Joeseph - would this type of install also work for a 18” overhang?
Suzanne
7 years ago
Joseph - would this type of install also work for a 18” overhang
Kathy Drakos Cattano
7 years ago
I would totally defer to Joseph who is a professional in the industry. You may also wish to speak to your local fabricator whom you will be using! Good luck!
PRO
Joseph Corlett, LLC
7 years ago
That would go to 18" with no trouble.
edanz
Original Author
7 years ago
last modified: 7 years ago
The cabinet maker just told me that the posts will be constructed using MDF board to create a solid block. I imagine that is probably Ok, since they bear the load vertically, but if he suggests using MDF for the apron stretchers, that would be a definite no, am I right?

I will definitely talk to the cabinet maker about adding cross pieces. Also, suppose that instead of 2 x 3 1/8 inch for the stretcher boards, I asked him to use square "beams" of 3 1/8 inch. Would that add more strength and combat warping? I'm not sure I can get a custom made steel frame. That is highly custom work here and would add several thousand euros to the cost. The legs and apron alone is probably going to set me back 3K.
User
7 years ago
If he is building a decorative box post out of MDF, it should be around a structural wood or steel post. No stretchers should be MDF. MDF is fine as a cabinet box material when joined correctly. But the spans are short, and the joins shouldn't use pin nails as anything but as fixing agents until adhesive sets.
PRO
Joseph Corlett, LLC
7 years ago
edanz:

There is nothing wrong with MDF legs, hollow even, loaded vertically. I'd have him rip a piece of Laminated Veneer Lumber (structural plywood) for the stretcher with the LVL let into the top of the leg to transfer the load to the floor. Make this stretcher as deep as your decorative eye can stand, please, but 3 1/8" of LVL will span 51" without sagging. Two legs, two small stretchers on each end, and the 51" stretcher between the legs is plenty. These details will save you the cost of a custom metal frame, but are critically important.