The island is probably 2cm with a thicker edge to cover the steel underlayment required to keep the cantilevered span from sagging and subsequentyl causing the waterfall miters to self-destruct.

I see. that makes sense. thank you.

There is a lot of invisible custom steel in that picture that you cannot see. The island cabinet design has to be planned well in advance for that steel support for the tops and ”legs” to integrate to those cabinets. You can not add it later and interfere with the door clearances or panel attachments.

With the way lead times are these days, all of this had to be planned 12 months ago, before ordering a single thing. That is what kitchen design is. It is advance planning of all technical aspects to integrate properly.

From your many questions, it sounds like none of your counters, overhangs, or appliances, were planned by the cabinet seller who sold you some pretty expensive cabinets, but with no design plan.

Thanks.

It is primarily the issues on the GC side.

Cabinet design were done a year ago, with the anticipation of using 2cm quartz and the 4cm edge profile, with island being the mitered edge. Cabinet seller indicated to use plywood underlayment for the counter and island.

Now the GC along the way asked me to purchase 3cm quartz for the durability of it, saying that we can change all the edge profile to 6cm. There is one cabinet at the corner that would need to open right above the counter, and with this additional height from the 3cm quartz and edge, it may not have enough space to for that cabinet door to open.

So I am looking for options -- or maybe just simply switch out the 3cm quartz for 2cm ones. -- I already paid for some pretty expensive quartz, and don't know whether the stone distributor would let me switch (presumably 3cm is more expensive than 2cm, so they might be ok).

Just answered your other post about fitting your refrigerator columns.

It sounds as if you have an incompetent GC. I think you should consider getting a new one ASAP.

Slabs come in 2 cm and 3 cm thickness and their availability is usually regional. I lived in CA and most slabs were 2 cm. Now in FL and most slabs are 3 cm.

In CA I had to have a laminated or mitered edge to build up the 2 cm slabs to cover the plywood underneath.

In FL you just use the 3 cm edge and finish as desired.

I much prefer the 3 cm slabs with no need to laminate/miter the edges. No plywood needed. Just one less thing to go wrong!

Thanks again to all who responded. Now that I feel that the GC cannot be trusted at all, I am paranoid and start wondering:

Can the waterfall can sit directly over the engineered wood?

We have approx. 24'' and 12'' deep cabinets sitting back to back for the island, adding 12'' overhang. There will be plywood underlayment before the stone go on top of the island. It is a 8ft long island. Without the waterfall edge, it seems that the overhang should be ok and the weight of the island countertop is properly supported.

Now how about the waterfall sides? Can the stone for the waterfall (legs) sit directly on engineered wood? Can the engieered wood flooring be installed first and then the island waterfall? If so, what do I need to pay attention to (even if I fire the GC and hire a new one, I still want to understand better so I don't end up in another mess)?

" Cabinet seller indicated to use plywood underlayment for the counter and island. "

Why does he feel plywood underlayment is needed? Plywood offers no support for an overhang of any size and has zero place in this equation. You need custom steel that is designed and installed with your cabinets.

Waterfall edges shouldn’t go on floating floors - the concern is the material will pinch the floor and it will buckle under stress from settling. Is the engineered wood floating or glued/nailed down?

@ Joseph Babcock, Glued / nailed down engineered wood. is it ok then?

I would double check with a qualified gc but should be.

@millworkman The quartz manufacturer has a guide saying that the 3cm quartz can have a 15” unsupported overhang. so without the waterfall edge, just the 24”+12” base cabinets and a 12” overhang, is it ok without the steel? this would stoll be under the 2/3 vs 1/3 too (12” overhang is just 1/3 of thr total width of the island.

now adding the waterfall edge, does it need additi suppsupport?