Granite counters round or square inside corner

Jeremy DuboysApril 8, 2014


I recently had my granite counters installed and to my surprise it came with a round inside corner. I always assumed that they squared off the inside corner to follow the cabinet line and I am unsure if I like it rounded. Is this something that is standard? standard. Please take a look at the attached picture to see what I mean.


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Both the granite countertops I had up until 2 months ago and the quartz countertops that replaced the granite have inside rounded corners. Never gave it much thought but perhaps one of the fabricators on this forum can offer an explanation.

    Bookmark   April 8, 2014 at 8:56PM
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Jeremy Duboys

Yes I would love to hear one of the fabricators thoughts. Id also like to know if this is something that could be changed on site or not

    Bookmark   April 8, 2014 at 9:16PM
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When you cut a piece of glass, you first score it, meaning you scratch it along where you want it to crack. This is a stress point in the crystal structure that is weaker than the rest, so a crack tends to run along it.

Likewise, if you cut a square inside corner in a stone slab, you have created a concentrated stress point where a crack is more likely to start. By making instead a gentle inside curve, you are distributing the stress in that area across the curve, instead of concentrating it into a point. This in effect strengthens the corner. That's why they do it.

    Bookmark   April 8, 2014 at 9:21PM
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The rounded inside corners are typical. Usually because the tooling leaves it that way and it's more work to square an inside corner. Many fabricators claim rounded inside corners are necessary because of the reasons previously stated. While true in glass, steel, plastic etc. stone is different. Stone is loaded with natural fissures and fractured "grain" structures that will make rounded corners less effective in preventing stress risers. Because no actual testing has proven rounded inside corners prevent or are non-effective in preventing stress cracking in stone fabricators adhere to rounded corners as a precaution. There are many squared inside corners done in stone with no problems. A proper stone install will not have any stress in the corners. If there is stress in the stone it will crack, rounded corners or not.

    Bookmark   April 8, 2014 at 10:17PM
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You have radiused (is that a word?) corners on the outside, and the inside was done to match.

I have mitered edges with square outside corners, so I also have square inside corners.

    Bookmark   April 9, 2014 at 3:09PM
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I am a fabricator.

In the past 10 years CNC finished edges have come to dominate the industry. They save several hours of labor per kitchen at the cost of a finish quality that is inferior to a hands finished edge.

When the edge is a shaped profile like Ogee or bullnose the radius of the CNC tooling (which is a cylinder that is a mirror image of the edge profile) dictates a rounded inside corner. It takes real craftsmanship to hand grind a shaped edge profile on an inside corner.

A flat edge like in the picture could certainly have been a sharp inside corner as it's far easier to finish out by hand than a more complicated edge shape.

    Bookmark   April 9, 2014 at 4:11PM
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Jeremy Duboys

Hi, thank you.guys.

Oldryder, Thank you for your response. If I understand correctly having the inside corner rounded was just easier to do and that is why he did it. Now that the counter is on, is it possible to square off the edge in my house?

Errant, I should have specified that the picture I uploaded was in my house as I am not living there yet and didn't have a picture. I did stop by today and took some pictures. As you can see the outside corners are much less rounded then the inside corner.

Here is the inside corner

    Bookmark   April 9, 2014 at 4:20PM
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Jeremy Duboys

And here is an outside corner

This post was edited by jdubs79 on Wed, Apr 9, 14 at 16:24

    Bookmark   April 9, 2014 at 4:21PM
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I have a G-shaped kitchen, so I have three inside corners, none of which are rounded. I'm not sure if that's a good thing or not. :) I think I would have been mildly annoyed if they'd been rounded and would have probably gotten over it.

    Bookmark   April 9, 2014 at 4:52PM
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Jeremy Duboys

Linelle, yes I will definitely get over it, it's just not what I was expecting and is something I would like fixed if possible. Definitely not the end of the world though.

    Bookmark   April 9, 2014 at 5:02PM
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I take it you didn't discuss the inside edges at templating time? My fabricator asked before I could tell them that I absolutely did not want a radiused inside corner. I specifically requested the outside corners be very square, just barely rounded, and chose an edge as close to square as they are comfortable doing with marble. An rounded inside corner would have spoiled the clean-edged, straight-line look for me.

On the up-side, your stone is really gorgeous! I can't wait to see more.

    Bookmark   April 9, 2014 at 7:44PM
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It can be squared-off in place, I know this, because our fabricator originally gave us a heavily radiused inside corner which we certainly did not want, and we had them cut/reshape the corner the day the counters were installed. They covered the cabs below with cardboard, and cut back the radius into a "soft" 90-degree corner (which is what we had wanted, and thought we were getting in the first place).

I will warn you, you might not end up with as nice and as straight an edge if they do this onsite/with the granite installed (if you look down the length of our counter, you can see it's not quite straight as it nears the corner). Also, I had to have them come back a few times to "fix" or "finesse" the slight bevel (at the top and bottom of the eased edge) on the section of counter between the corner and the range to match the rest of the counter(s).

It's not perfect, and nobody but us, and a good friend who's an architect would notice it unless looking for it. It would have bugged us even more to have that huge radius, which not only did not provide the look we wanted, also took up more space in the corner than we wanted to give up (that's my prime prep zone--right near the range).

    Bookmark   April 9, 2014 at 9:38PM
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Jeremy Duboys

No we didn't discuss the corner, I just assumed it would be straighter.

Thanks for the compliment on the stone, once it is finished I will definitely post pics.

    Bookmark   April 9, 2014 at 9:52PM
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Jeremy Duboys

I am happy to report that the fabricator was able to square off the inside corner and it looks wonderful!

    Bookmark   April 10, 2014 at 2:57PM
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Wonderful news!

Pics, please!

    Bookmark   April 10, 2014 at 3:14PM
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Jeremy Duboys

This is the only pic I have. You can make out the corner in the back but I don't have a close up yet.

    Bookmark   April 10, 2014 at 6:45PM
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Jeremy Duboys

Now I have another question. As you can see from the above picture we have a 12" overhang on two sides of the island. My fabricator said I did not need any supports (corbels, etc) but in reading these forums I am seeing that supports are recommended for anything over 10 inches. Will this be ok without supports? Would it be possible to put supports in when the counter and cabinets are already installed?

    Bookmark   April 10, 2014 at 8:57PM
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Glad they were able to redo/correct it for you.

    Bookmark   April 10, 2014 at 11:06PM
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What a wonderful update! So glad they were able to fix that corner for you, it's looking great.

I'm not sure if supports are needed or not for your island, we have a similar sized island and have 4 supports on our 12" overhang. I hope someone who knows posts soon for you. :)

    Bookmark   April 10, 2014 at 11:33PM
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The industry trade group MIA (Marble Institute of America) allows an unsupported overhang up to 12" so technically you are OK. In my experience, on many stones, this is too much because of fissures in the stone. In some instances we will rod the overhang which doesn't improve the strength significantly but it does prevent a broken piece from crashing to the floor on to a foot or a kid,

I'd do 12" overhangs on quartz all day long. On granite we usually encourage the customer to provide some support out to 6 or 8 inches. If the supports are low or zero profile they won't be knee knockers. "Zero profile" supports are actually embedded in the stone and are invisible unless you lay on the floor and look up at the underside of the stone.

Corbels must have structural support in the cabinet to be worthwhile. Often they can't be added after the fact because there isn't any robust structure in the cabinet to anchor the corbels.

    Bookmark   April 11, 2014 at 9:14AM
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Love the kitchen and counters!!! Of course I'm biased in regards to the stone :-). We also said that we wanted squared corners, but to have them soften them up just a tad.

They are like that all around our kitchen with the exception of the stone bump outs around our range. Kind of a funny story, but we actually used one of my sons legos as the guide for that!

Looking forward to more pics of your kitchen!

    Bookmark   April 11, 2014 at 9:33AM
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The bigger the radius, the stronger the corner. Estone and solid surface manufacturers have fabrication instructions that include minimum inside radii.

The pictured corners look good to me.

    Bookmark   April 11, 2014 at 11:20AM
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Jeremy Duboys

Thanks for all the help guys! I can;t believe how amazing and helpful everyone has been so far. Hopefully I can contribute soon.

    Bookmark   April 11, 2014 at 11:22AM
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Thanks SO much for this post! I just chose my marble slab today and happened to ask them about inside corners. Like previous posters, I had no idea that I needed to specify that I wanted square inside corners. I was told by our stone people that it's standard to match outer and inner corners, so if you have a soft/rounded outside corner, they match the inside corner to the outside unless you specify that you want a sharp inside corner. These pictures were very helpful, thanks!

    Bookmark   June 27, 2014 at 8:39PM
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I never thought to ask about most of my corners. I did ask for a small radius on my overhang. My family is clumsy and I figured it'd be more forgiving when walked into! My other outside corners are all just barely rounded and my insides are square.

    Bookmark   June 28, 2014 at 8:35AM
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This just happened to me today. they put in my granite and the inside corner is round! I hate it! I have straight edges and square corners, I have shaker style cabinets and wanted a clean crisp look and I got this ugly curved corner. I called them and said no way I need the corner like the edges "square" So I am waiting for a call back but they sounded like they are going to give me a hard time because they said I had to specify that ? Oh boy!

    Bookmark   November 18, 2014 at 10:58PM
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