Island Counter Overhang Support

12 years ago

I've seen this topic tackled many times on here, but there's one aspect I'm still unclear on. How do you prevent the granite from cantilevering over the back of the cabinets and sliding off?

I have two 27" wide cabinets for my island and a 15" overhang off the backside. I was planning to use the Amastin single level bar supports to prevent the granite from cracking due to cantilever stress. However, I don't see how they prevent a seesaw action from occurring with the whole slab of granite. I tried to draw what I'm worried about below. If the weight of y is over 61 lbs, sees like a seesaw action would result...

I don't see holes in the Amastin supports to drill the ends into the cabinets to hold them down and prevent this. Even if there were, I'm not sure I trust the cabinet walls or face frames to handle so much weight.

Is this something that people don't usually bother with?
{{!gwi}}From Shared

Thanks,

Justin

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Comments (3)

angie_diy
12 years ago
Let me first attack your drawing as is, but I have a question about your Amastin supports.

We are not worried about force, we are worried about torque. Torque A can be calculated by assuming that Force A acts at a point 12.5" to the right of the edge. Torque B is found by assuming Force B acts on a point 7.5" to the left of the edge. Torque C is found by assuming your clueless friend's weight acts 15" left of the edge.

Torque A = 162 lb*12.5" = 168.75 lb-ft.
Torque B = 101 lb*7.5" = 63 lb ft.

To tip, Torque C would have to be 168.75 -63 lb-ft = 105.75 lb-ft. So, your clumsy friend would have to weigh 105.75 lb-ft/1.25 ft = 84.5 lb to tip your counter. Still not good.

However, the effect of the Amastin overhang brace is to shift the pivot point to the left. I think you are supposed to get the one that is 33.25" long. I believe this would stick out from the back of the cabinet by 33.25" - 24" = 9.25". This would mean that the pivot will be about a point that is 9.25" left of the back edge of the counter. This changes your numbers to a much more favorable condition.

Now, Force A is 18lb/ft^2*4.5ft*(25"+9.25")/(12"/ft) = 229.5 lb and acts (25"+9.25")/2 = 17.125" to the right of the pivot. Ergo, Torque A is 229lb*17.125"/(12"/ft) = 327.5 lb-ft. Force B is only 38.8 lb and Torque B is only 9 lb-ft. Your clumsy friend would have to weigh 664 lb. to tip the slab.
angie_diy
12 years ago
Oh, I now see that you didn't think the bar is attached to the cab at the front. I think it is. Look at this response from Stacey Womble, who, in a different thread, reveals himself/herself to work for Amastin. S/he says that the bar attaches to the front face frame of the cabs. This would make it operate in the way that I described in my post above. I agree with you that if the bar is not attached to the cabs, it won't prevent cantilever action.

Here is a link that might be useful: Stacey Womble works for Amastin
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Jumpilotmdm
12 years ago
A 15" overhang seems excessive. See if you can live with 11" or 12".

Island Counter Overhang Support

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angie_diy

angie_diy

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