The question is how far can granite overhang before it needs support? Since the weight of granite can cause it to crack, making sure you have the proper support is essential. In most cases, support is placed underneath unless the overhang is 6 inches or less. You can safely overhang granite that is 1 ¼ inches thick up to 10 inches without support. However, the cantilevered portion cannot be more than one-third the total width of the countertop. Natural stone can be cantilevered up to 12 inches if it’s a thick piece with sufficient support on the fixed end. It should never be cantilevered where it might receive excessive stress, such as where someone may be tempted to sit on it or use it as a stepstool.
Once again, it is absolutely necessary to use under counter support brackets of some type to support granite, marble, and limestone kitchen island countertops that can have overhangs weighing hundreds of pounds. Countertops made from natural materials, obviously, are not subject to the typical quality control processes found in modern manufacturing and therefore, they are subject to irregularities, some of the very features that make them attractive. These features also add fault and fracture lines that can make them brittle and subject to breaking and the part that breaks off can cause damage and / or injury. If anything, this highlights the necessity for some type of structural support. Considering the cost of granite coupled with its heavy weight, it would be advisable to support any overhang just to ensure your granite never runs the risk of cracking, which in most cases cannot be repaired. Brackets for supporting granite can be either functional, decorative, or both depending on the installation. You will find that hidden heavy duty, solid steel supports are especially practical.
Countertop supports come in a variety of shapes and styles. The 90-degree steel bracket is one of the most practical and easiest to understand and install. One of the most popular, and strongest, is Tech Team’s #781 8 inch x 8 inch 2 bracket set https://techteamproducts.com/product-category/shelf-and-counter-brackets/ https://www.amazon.com/dp/B07PCRB9KM?ref=myi_title_dp ,you can do a hey Alexa or hey Siri search for other options but, you will find this one to be one of the best. They measure 8” x 8” x 2 3/8” and are a full ½” thick with beveled ends and a durable black powder coat finish – they are super heavy duty to say the least. They are also available as a 4 bracket set item #732 https://techteamproducts.com/product/8-x-8-granite-countertop-bracket-4-pieces-00732/ https://www.amazon.com/dp/B07G1KQPPQ?ref=myi_title_dp Whatever your needs, these will get the job done.