I am constructing an 10 ft island with a 45" granite diam circular peninsula off the base to be used for a dining table. I would like to support it with one steel post. If I don't place the post in the center of the circle but near the end, how small of a diam can I get away with and still be able to support the granite top? How far away from the edge can I go (closer to the center) and still have the best support all around? Thanks
Andrea

Several factors will come into play in determining the size of the top post placement etc. One being the thickness and the type of granite your using. Granite has graining that often weakens the slab so depending on the material you choose will depend on how big and how far of a distance the post can be from the edge. You will still need to support the underside of the stone with a base of some sort. Simply putting the stone on a post or even plywood under it will not support the stone enough and keep it from cracking. AS far as a post size a 1-1/2 inch steel post would be more then enough. As far as putting it in the center which I assume is to allow for feet clearance below, You can angle the steel up from the end of the cabinet at a 45 degree angle to provide more room for legs. You need to check with the granite people your buying the stone from. They are the ones that will warrnant the install and the top. Let them tell you what they will be comfortable with as they will use any excuse they can not to fix a cracked top. Also get their advice in writing. They will forget what they told you when you come to them if it does break.

thank you. What about a post from the center of the granite straight down or about 12-14" off the end down to the floor. Granite is 3/4" thick.

you can place the post there, but remember the graining in the slab is the weak spots. Just because it is heavy and 3/4" thick does not mean that the slab will not crack. Even with a 3/4" layer of plywood under it the possiblilty of bowing can occur. You may not even see this minute amount of movement but the slab will see it and then can crack quite easily. Check with the granite company and ask them what will work with your selection as they are the ones that need to warrant your new counter.

thank you. We are using tan brown. We definitely want to go with one post and are thinking of using a 5" wooden island post. If we place a 12" diameter metal plate attached to the top of the post and then to the plywood under the granite, distributing the weight, would that give enough support?

The color means nothing, its the graining of the material that makes it weak or strong depending on how much it there. The wood post will work, Just check with the granite people first before you go through the expense of purchasing and installing the post and extension to be sure they will warrant the top should it crack.