First of all, the recommended seating overhang has nothing to do with counter material...it applies to granite, soapstone, quartz, wood, laminate, etc.
Second, you will need support for any material...for stone, follow the "6 & 10" rule.
For 2cm stone, any overhang > 6" will need support.
For 3cm stone, any overhang > 10" will need support.
So, for the recommended 15" overhang, you will need the following support: 2cm stone: 15" - 6" = 9" of support
3cm stone: 15" - 10" = 5" of support
For a 12" overhang...you do need support...2" of it for 3cm stone & 6" for 2cm. Anyone who tells you differently is incorrect.
Some people will skimp on overhang for a variety of reasons (most commonly b/c they're trying to squeeze in seating where there really isn't room or they're trying to avoid having to support it). However, skimping on overhang, while it may reduce or eliminate the need for support, will not make an inadequate space "work". People will take up the same amount of room regardless of the overhang you provide. The adult human body can "squeeze in" only so much. What happens is that people will still sit as far back, but now they have to lean in quite a bit further to reach the counter or they have to "straddle" the cabinets or they have to sit sideways. None of those is comfortable for any length of time. It may be OK if someone is just "perching" for a short period of time, but not for prolonged conversation & visiting or meals (even breakfast or lunch).
Yes, people in general can adapt to or "make do" with just about anything (that's why people will sit sideways, straddle, etc.), but is that the goal of your remodel...to "make do"? If you're spending all this $$$$ on a remodel, I would think you would want to make it the best you can...first & foremost functionally and then aesthetically.
So, don't skimp on overhang and plan for
adequate aisle widths,
adequate workspace in the primary Zones (Prep, Cooking, Cleanup),
adequate work and landing space around appliances (cooktop/range, refrigerator, oven(s), sink(s), DW, etc.), and
good workflow...Storage --> Prep Zone --> Cooking Zone --> Cleanup Zone w/minimum zone crossing/overlaps/conflicts.
Good luck!
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overhang discussion
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