"Is there such a steel support bracket that is only 1/4" thick and still strong enough to support 3cm granite?"

No. The granite fabricator is correct here. From your pictures, it appears you have plenty of room to let a 1/2" bracket into your cabinets without interfering with your doors/decorative panels. I'd recommend these.

Thank you for your guidance, Joe. I've added another photo that shows that I really only have 1/4" of space above the cabinet panels. And, the panels cannot be lowered. If there is no such thing as a 1/4" thick bracket, will I have to allow the countertop installer to router into the panels? Is that wise? Are there any alternatives?

My steel brackets/stone braces came from Granquartz. 16" overhang on 3 sides, 3 CM granite, 5x8 Island. Fabricator estimated island top to weigh 700-800 lbs.

I have 3 of them and the legs for additional support.

The supports are anchored to a 2x6 or a 2x4...can't remember...in the cabinets.

HU:

Please reread your framing square. It shows you have 9/16"+ from the top of your panels to the top of the cabinets. The 1/2" braces will work perfectly as is.

I am having a similar dilemma except not with fake doors, mine are real doors, so routing into them is not an option. To the original poster, what was the outcome? Or anyone else who might see this post… any advice?

Sarah:

It would be helpful if your stone were 2 cm with a 2 cm edge build up. That would get you 3/4" of space for square tube steel that would be flush with the bottom of the edge. This is something that a good kitchen designer would know.

It may be possible to drop your doors or to reinforce your overhang with rodding. What is your top made of and what is the thickness? Dimensioned drawing please.

Joseph, thanks for commenting. It’s viscount white granite. Just realized I don’t know the thickness. Attached is a drawing I made this morning to document the specs. The island cabinets measure 8’ x 3’.

Just an update to close the loop here and share my result for anyone who may be searching on this topic in the future: the granite is 3cm thick. I bought 1/4” thick support brackets from Federal Brace. My GC was able to drop the doors a smidge and cut into the cabinets to attach them. I know that people will probably say that 1/4” brackets are not thick enough. But for better or worse, thats what we did.

Hi Sarah, we have a similar problem. The rail for our full height doors is very thin, like 1.25”. We’ve dropped our doors to accommodate 1/2” brackets but it makes the rails that much thinner. Did you re-enforce the rail/frame with anything?