We just had a granite countertop installed in the kitchen (stone name: Golden Beaches or it is sometimes called Persa Classico, I believe it is Italian). We have a 12″ overhang at the peninsula, which is 86″ long. When they came to template, they said that they were going to add steel rod supports for the overhang. After it was installed, I noticed that there were no steel rods. I inquired with the installer and he said that it was fine. I have been doing some Googling, and I am concerned about this overhang without supports. I cannot add corbels, because it would ruin the design (the back end of the peninsula has furniture panels that would look horrible with corbels. Is there a way to add the steel supports after installation? Or, is it really ‘OK’ as is?

Thank you, Barbara

Hello Barbara,

The installation you described with the 12″ granite overhang will crack and fall eventually. As you mentioned, it is 3/4″ thick with no corbel or steel angle support, and it does not even have embedded steel rod. I expect that gravity alone will stress this particular granite enough for it to crack along the cabinet edge. If you take a level and lay it on the counter, you may even see a 1/16″ sag already.

You should search the ‘overhang’ on my blog and read the comments that I have already written about cases like this. In particular of your situation, the Juparana Beach granite is a Class D granite, which only means that has more natural fissures; this, creating weaker flexural strength. Basically, it is more fragile to horizontal forces like gravity. I love the color and it complete fine when adequate supported.

The embedded steel would have at least stopped the granite from falling on the floor after it cracks. I don’t believe that embedded steel would have prevented it from cracking because the horizontal forces at a 12″ cantilever is too substantial from gravity and unnatural forces like heavy objects resting on it. I understand your problem with the decorative facing on your cabinets which prevent using corbel supports. This is not uncommon. In this case, heavy duty 1/4″ thick flat bar is embedded into the plywood substrate and place about 18 inches apart. These bars run from just behind the front edge of the granite bullnose to about 12″ back from the cabinet (into the cabinet area).

If your granite was recently installed, I would ask the fabricator to try to remove the granite without breaking it (might not be possible) and install the steel flat plates. If you don’t do this, your granite will eventually crack. Because it does not even have embedded steel, it will fall. Hopefully it will not crush someone’s toes or a small child’s head. Frankly, the installation you described is very hazardous. Sorry for the bad news.

This entry was posted on Thursday, June 21st, 2007 at 10:12 am and is filed under Answers to Granite Questions..., Installation Issues, Other Topics. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.