I will merely say that a neighbor of mine used HD for corian countertops (they always contract countertops out, no matter the material--they're just brokers), and had a problem with the installation, and then went through absolute hell with the installer refusing to fix the problem and HD saying it was no concern of theirs.

I would strongly suggest going direct to a fabricator instead of through HD. You gain nothing from using them.

Some HD stores are fine; others definitely are not, but you have no way to know unless you know folks who have used your store and their chosen fabricator before.

Can you mark/clarify where he says the seams will need to be? That will likely help the countertop gurus.

FWIW, we used IKEA for Caesarstone countertops. The templater initially said there would be two seams. I pressed the issue and found that IKEA pricing is based on the easiest possible installation, which would include a seam at any corner. I could (and did) opt to pay for the additional square footage needed to not have seams. Maybe that's a possibility for you?

writersblock - thank you. I would agree, but with this fabricator, all their poor reviews are from people who went to them directly. All the 5 star reviews were from people who went through Home Depot. So I'm a little more at ease regarding that issue (at least with this local store). Also, I already paid. So there's that. :/

Oh, I'm not saying you should go direct to their fabricator, far from it, but even in my little town we have more than one place that does quartz. Sorry I wasn't clear.

But if you can't get your money back, I guess you have to go with it.

ETA Have you gone to HD and tried? I suspect that if you can give them an idea that you are likely to be a very difficult client, they might.

I did get an email back from the fabricator saying: "It is never a good idea to
place a seam too close to a sink, as sinks are the most highly trafficked place
in a kitchen. If the seam on your sink counter is moved, additional fees would
be incurred due to the large size of that countertop, and the chance of that
large countertop breaking in transport, during installation, or later on down
the road increases. My recommendation is to leave the seams as they are. They
are currently placed strategically to avoid breakage of the countertops as your
home and cabinets settle over time. All foundations and cabinets shift over
time as the ground beneath settles, and having seams placed on either side of
the dishwasher and sink help alleviate pressure on the stone during that
process. If at any point this happens to your countertops, you simply call
Stoneworks to come out and reset the seam, just like during the first
installation! However, if we removed or moved the seams, during that same
settling process the stone can crack and break, especially in those high
traffic areas like dishwashers and sinks."

The idea that it would break in transport or during installation because of size seems bogus to me. If they properly secure the piece and have the right number of workers moving it (mine required 3 instead of the typical 2, for 104 inches) that shouldn't be an issue. I would be interested to hear what some of the knowledgeable countertop folks here have to say about cracking over time because of settling. I would think that if it were leveled, shimmed, etc appropriately from the start that this wouldn't be an issue either, but I'm definitely no expert.

My quartz went in yesterday with almost same layout except mine are longer runs and my cooktop and sink are flipped from yours. We did a seam at cooktop (they cut on site) and another seam to the right side of the corner straight vs angled (where the number 14" dimension is notated on your drawing). The contractor had ordered jumbo slabs so we got away with only two seams.

I have a tabletop in Silestone that I ordered through my local HD. Same deal, they gave the job to a small local company. It went smoothly enough, though I didn't like that there was a delay of a few days every time communication had to be relayed through HD. Up front, I only had to pay for the measuring visit ($100 or so) until the job was next in their queue, then they phoned me for full payment. Maybe you haven't paid in full yet and can shop elsewhere? In my case, the end result is what I expected which is good but not perfect, but the price of Silestone is rock bottom compared to other similar looking products so I kind of expected flaw or two. Nothing anyone else would notice.

When they were in for the table top, I asked about counters and because we'll be replacing ours in a few months. The rep said they would not do diagonal seams because it uses too much material. The guy was not the sharpest tack so I didn't push the "what if I pay more for it" angle, figuring I'd cross that bridge later if I end up ordering from them again. Long story to say, though I know they're not popular, I think mitred corner seams like the red lines in your drawing make the most sense visually, though I don't know anything about structural advantages/disadvantages. Especially if they might be noticeable, I'd want the mitre. I personally don't like straight seams that break up a run. Maybe it's from a few decades working in picture framing, mitres just seem the most logical.

Jen Mark:

Sorry, but there's no such thing as a 150" piece of estone, not even a jumbo. Were you my customer, you'd get what, where, when, and why, and I'd keep how and who.

The big fat red lines are wrong. I'd probably give you a french miter at the short end, but I haven't taken the time to figure yield.

The big fat red lines are the fabricators.

Sorry, I've corrected the drawing to show the correct area where the seams are - they're actually not diagonal but are straight (which is worse looking IMO). The actual seam placement is highlighted.

Is there any possibility of just one seam? Joseph mentioned that because of length you would need a seam, but I wonder if you can get away with only one. I would guess you'll spend the most time between the sink and range for prep, so I'd try hard not to have a seam there. Unless you're confident that their seams will be very inconspicuous.

jesslake: You were correct - I was wrong about the diagonal seams. I got the paperwork back from them and saw they are actually vertical - sorry for my mistake!

kathryn p: this is the response I got from them: ". My recommendation is to
leave the seams as they are. They are currently placed strategically to avoid
breakage of the countertops as your home and cabinets settle over time. All
foundations and cabinets shift over time as the ground beneath settles, and
having seams placed on either side of the dishwasher and sink help alleviate
pressure on the stone during that process. If at any point this happens to your
countertops, you simply call Stoneworks to come out and reset the seam, just
like during the first installation! However, if we removed or moved the seams,
during that same settling process the stone can crack and break, especially in
those high traffic areas like dishwashers and sinks."

So they kinda make it sound like if I don't use their seam recommendation, then they won't come back out to "reset the seam".

Are they using remnants or full slabs?

Full slabs as far as I can tell.

Jen Mark, the seams in my Cambria counters are as shown in your drawing. I have a closeup somewhere, but not on the computer I'm using now.

Can you see the seam? I really have to look for it in real life. If your fabricators do a good job, the seam should be almost invisible.

With two slabs, can't they get away with only one seam? I'm too lazy to do the math.

These guys are trying to use up remnants, guaranteed, because there is no way you need two seams in your sink top. What a bunch of hokum about settling. Install your cabinets with EZ Cabinet Levelers and you raise the cabinets and tops simultaneously if there is any settling. I confirmed that with the inventor at the KBIS show two days ago. Plus, this is estone, not granite. It flexes a bit without breaking.

Well if they are using remnants and they are the cheapest, then that explains it. Were they the cheapest?

AnnKH - nope - can't see a seam at all! That does ease my fears a bit.

Joseph Corlett - see, that's the feeling I got from them when they were explaining it. So frustrating. And my cabinets are already installed, I'm not doing anything to the existing ones, just adding new counters on top of the old ones.

smm5525 - I went with Home Depot. No idea if they were the cheapest.