The allowable overhang with no additional support is no more than 1 3 of the depth of the countertop and not to exceed 15 total.
Quartz countertop overhang without support.
As the chart indicated solid surface countertops may only overhang 6 inches without additional support.
Most granite fabricators will recommend support brackets on overhangs over 12 however solely based on the overhang amount.
According to the marble institute of america you can safely overhang granite that is 1 1 4 thick up to 10 without supports.
However you may need to install supports such as corbels or legs.
However the cantilevered portion cannot be more than 1 3 the total width of the countertop.
Because not every bracket is the same certain support brackets may be too weak to hold stone like marble granite or quartz.
In conclusion the answer to the question how far can quartz overhang without support is.
Without any additional support solid surface countertop overhangs cannot exceed 6 engineered stone cannot exceed 14 and granite overhangs shouldn t be more than 10 without additional supports.
Amount of overhang you have is the most important factor to consider in deciding whether you need support brackets.
However once you gather your information and find out from the installation guide for your material you will then be better prepared for selecting countertop support brackets that are designed for your purpose.
Yes you can extend the overhang on a kitchen island countertop.
Even leaving your brackets weakly fastened leads to inadequate countertop support.
That depends on many factors regarding the project material and the thickness of the surface.
Overhangs greater than 15 require the installation of corbels.
That said there are standard dimensions that can help guide you as you plan out your kitchen remodel.
Alternatively a weak bracket may not support the weight of the countertop overhang.
3 cm quartz engineered stone can handle a 14 inch countertop overhang without additional support 3 cm granite overhangs should not exceed a 10 inch overhang without additional support bearing in mind the 70 rule.
So we are ok on the first criteria but we exceed the 1 3 criteria by four inches.