Is there a building code that I can look this up for? I feel like I need to prove to my countertop guy that we should have it! He seems so resistant to the idea and keeps saying that quartz is so strong it cannot break!

There is no building code that addresses countertop overhangs. At what point it needs support depends upon multiple factors, not solely just the overhang. We listen to the advice of our fabricators when they are onsite for template. If we question, we add support anyway.

We generally add additional support using the Fast Caps Speed Brace, but you can't add that (or anything similar) after the countertop has been installed. The addition of brackets does not always work after countertop installation either because there may be nothing substantial enough to screw the brackets into. All depends upon how the cabinets are made. You may be limited to adding some legs under the countertop if there is a way to secure them to the floor.

I would look on the website for the quartz manufacturer, and see if you can find a recommendation there that might specify if it is needed structurally.

In theory, anything over 10" should have support.

The marble institute has a homeowners guide for stone countertop installation. They indicate it would definitely require supports. This is dangerous.

I found this to be very helpful - from a fabricator that only deals with engineered quartz. http://www.capitolgranite.net/products/quartz/

Brickwood Builders - That's a great article. So the question is - how thick is your countertop? And how is it installed?

Thank you for the article! We have 3 cm quartz that extends 14" from the cabinet. The total width is 45", so it is (just barely) less than 1/3 of the entire width. I guess based on this article then we do not require support, correct? Am I interpreting this correctly?

Also they were installed by gluing them do the countertop, I believe. I do not think they ran a bead of silicone in between the quartz and adjoining cabinet.

That would be the correct interpretation based on this article. You may want to do some other google searches and you may want to send a question to the manufacturer of your particular quartz product. See if there is other information that would corroborate the article.

The manufacturer has the LAST word. As Brickwood suggests a photo with an email (tell them the name of the quartz, the town/city/state and name of the installer to be clear about what you are trying to communicate) with measurements. Ask them if they REQUIRE braces or if the RECOMMEND bracing. To be clear, a "requirement" = needed for warranty and should ALWAYS be followed. If they "recommend" the brackets/bracing it is a REALLY GOOD IDEA but not required by them for warranty.

Get this from the manufacturer and get it in writing. That will be the thing that tips this argument in your favour (requirement) or in your installers favour (recommended but not required).

As a fabricator I can tell you that 14" is the appropriate maximum for man made quartz countertops as long as that 14" is no more than 1/3 the total countertop width. If you have a 26" countertop 14" overhang is too much. You'd have to reduce it to 13". This is to avoid tipping. If you had a 28" counter then you can add the 14" max no problem.

Also as a fabricator is the frustration of dealing with every Tom, Dick and Mary pulling opinions out of the air and pretending to know something about other people's fields of expertise. If you do not know, do not alarm people with your bulcrap ignorance. Shut your mouth and look it up and find the facts. If you can't find facts don't make them up. I waste dozens of hours a year dealing with customers who have a know-it-all friend who spout their ignorance and we have to pull out our specification guides and re-correct our customers. In this case the fabricator gave you GOOD advice, and you managed to start a thread where ignorance reigned till someone posted some facts.

I have quartz with 12 inch over hang...my fabrication said I dont need support...Is this correct?

The biggest worry my installers worry about is the top tipping over. I would support that top.

Hi Corie, does your rule also apply to 2cm Quartz? You wrote: "As a fabricator I can tell you that 14" is the appropriate maximum for man made quartz countertops as long as that 14" is no more than 1/3 the total countertop width."

We are doing a 2cm Quartz without any plywood underneath with a 3/4" edge in a modern home and would like to do a 12 " overhang on a 52" deep slab so we meet the 1/3 rule.

Rob H:

See the chart on Page 20, please.

Yes it is needed on 20mm and 30mm stone or a pole support system, the above information is out of date by 8 years

Thanks! I guess i will have to talk with my fabricator. He is using MSI quartz and told me that 2cm should be fine up to 12" without any support since it is only 1/4 of the slab that overhangs. I called MSI myself to verify it and they said they don't have specific instructions/guidelines and said I should call my fabricator that "he will know".

I would go off one of the major manufacturers here is their recommendations.

"Yes it is needed on 20mm and 30mm stone or a pole support system, the above information is out of date by 8 years."

QSCCRE:

Since the information I linked to is virtually identical to the information you provided, how can the information I provided be "out of date by 8 years"?

Hi Joseph, I know this is an older thread but I'm hoping you would answer. If we had 63" wide slab with a 24" base cabinet on one side, a knee wall, and 12" base cabinet and then a 17"-18" overhang would we need support? It fits the 1/3 rule, but would support needed vary differently between a 2 cm vs 3 cm slab? Should we have brackets or plywood installed? Because our fabricator is really not wanting any overhang over 12".

Anything over 12" overhang needs to be supported regardless of if it is natural or engineered stone

This is great information. Thanks everyone. Is there a calculation that determines how much support? What kind of support? ie. The width and depth of the support itself (3"x12" support for 14" overhang) needed for every 12" over the length of a 6 foot counter.

Quartz / Kyle Thompson - your information says 400mm overhang with 3cm tops don't require supports- that's 15 3/4". Where is your 12" coming from?

If I've got a 30" cabinet and then an extra 47" overhang countertop that ends with a waterfall, is there any way to do some kind of hidden supports? I'd prefer that the overhang be open underneath without a knee wall.

following the fabricators rule of maximum overhang is no more than 1/3 of counter-top.... how much weight will that overhang tolerate without sagging or compromising the engineered solid surface? My plan is for LONG RUN of 8'8" quartz with 26" countertop and 13" overhang..... can I plop a kid ontop of that overhang in the middle of the run without support?

" can I plop a kid ontop of that overhang in the middle of the run without support?"

Sure, but as you sight down it in several years, you'll see a dip.

Does having an under mount sink in the island Change the length of the overhang I can have without needing extra support. I want to install a 52 inch slab with a 24” and a12” base under with a 12”overhang on 1 side

No.

Any links for installing Cambria countertop?

No, but Cambria has to have a fabrication and installation manual which sets the standards they require. If you can't find Cambria's, look for those of another manufacturer; they're virtually all the same because the product is.

Hello pmaeda, our technical resources can be found online at CambriaUSA.com/technical-resources or by contacting our Cambria Customer Care team at 866-226-2742.

Cambria:

Unfortunately your link does not include a fabrication and installation manual needed to answer pameada's question.

I love this thread as I am in need of help. I just purchased a new home from a big home builder and their cabinet person installed a counter island that fits the 1/3 2/3 arrangement but my overhang is 24” deep and runs 9’ long. When I look underneath there is no support in the middle of the counter. The only support are the legs at each end. I am afraid the middle is not supported and will eventually crack. The only way I noticed this is the cabinet guy made the underneath where my legs go too short by putting an apron across the front. I do not think this apron adds any support though. Help someone

"..but my overhang is 24” deep and runs 9’ long."

It's going to sag for sure. Picture please.

Problem is its not just the idea of of the counter will have issues but the island itself so the idea of only listening to the counter fabricator is just plain wrong.

So the counter guy says yes the counter can itself is rated to support itself for that overhang and that particular run of counter. What about the cabinets and or island itself? You have 14" of overhand creating a lot of leverage. A kid or adult hand or heavily lean on that edge and you can pull those cabinets right off the floor. Some cabinet guys barely fasten the cabs together or to the floor itself. So there is more to an overhang than just the counter. All just because it is possible doesn't mean you should do it. At 14" I would be adding legs and a skirt like a table or at least some bracing and having the cabinet guys accommodate for this.

We just remodeled our kitchen. Installed new cabinets with quartz countertops Now we realize that we should have made one side a lot wider. Is it possible to add on to an existing approx 12 in counter to extend it to 26 inches ? Or does it all have to be torn out and redone. I understand that the new piece might not match exactly and that there will be a seam. But to tear up the whole countertop requires re doing the plumbing and a lot more carpentry repair
This is the plan for extension. 14 inches at top.

I am in the process of remodeling my kitchen and my contractor put three metal braces to support my quartz breakfast bar. It seems sensible to me. Go with your gut.

If you are talking about extending an overhang, no you cannot add to an existing overhang. If that is not what you mean you need to be more clear in what you are attempting to accomplish.

"Is it possible to add on to an existing approx 12 in counter to extend it to 26 inches ?"

Yes, but it'll be pushing the boundaries of cost effectiveness.

Yes it is an existing overhang, but if you sit at it you are basically looking at a wall. My thought was if we could make it larger, you wouldn't be so close....and there would also be more work/eat space. The plan above is the proposal to completely tear out existing new countertop and replace it all the way around.....at a very high cost. I just want one side bigger.