threeapples- I was trying to match existing granite in my kitchen, but the only match was 2cm, which was thinner than the existing countertops. When I told my fabricator that I was concerned about the seam in the middle from a built-up edge, he said: "No problem, we'll cut all the pieces at a 45 degree angle and the seams will be along the edges where you can't see them." Take a look at these photos and see what you think: He even showed me samples where he had done this with highly figured marble, and he just matched the cut pieces at the seam line so it looked like the pattern wrapped over the edge and down the sides as if it were a solid 4cm slab. If you can find a fabricator who has the skill to do this properly, it's amazing, and they can give you whatever perceived thickness you want without obvious seams.

I'm in the middle of trying to figure out whether to go 2cm or 3cm, and I didn't even realize that granite came in two different thicknesses until recently. I wish my fabricator had told me that I could decide because I just learned that the slabyard has both thicknesses available in the stones I'm considering. The funny thing is that I moved to So Cal from Connecticut about 5 yrs ago and have renovated kitchens in both places. In CT, it was never a question, I just got the 3cm and there was no laminated edge and conversely, when I moved to So Cal 5 yrs ago and renovated (yet another!) fixer-upper, no one ever asked which thickness I preferred, I just went to the slabyard, picked a slab and it happened to be 2cm. I never realized that there was a thickness option, or that there even was a difference. Duh!! What should've clued me in was that in So Cal there was a lot of discussion about which edge detail to choose. Because I had black honed granite in CT and like a simple, plain look, I chose the same when we moved to So Cal (and, to make matters trickier, at that time, plain black honed granite was pretty unheard of around here so I don't think the fabricator knew how to deal with it well). He asked me how I wanted the edge, and I told him that I wanted nothing fancy, just a plain eased edge....I was SOOOO disappointed when the counters were installed and I saw this thin seam running through the middle of the edge. I had no idea that they would put an edge over the slab and didn't get how that could happen. Of course, the fabricator, thinking this was standard and thinking I knew what I wanted, having done it before, didn't really explain and warn me strongly about the seam issue. For awhile, I couldn't understand what happened and what was the difference between the way my counters were made in CT vs. here in So Cal. Now I get it. This renovation (yes, we've moved into yet another fixer upper - last one!), I'll go with the 3cm, but from what I understand, I need to warn my cabinetmaker that I'm using 3cm because I've heard he needs to adjust the cabinets tp accept 3cm. That's another difference between east and west coast situations...in CT, the cabinetmaker assumed I was using 3cm, but here in So Cal, the cabinetmaker is assuming I'll use 2cm and needs me to warn him if I use the 3cm. Just something to think about for those perhaps in similar situations - remember to confirm the size of granite with your cabinetmaker, in case he doesn't ask.

I'm not an expert but I recently had new countertops installed and have seen this explained so many times on this forum. It in fact, has been talked about quite a bit. 2 cm granite is more commonly used and costs less than 3 cm for the slab itself, but the price difference becomes negligible because the 2 cm requires more labor when fabricating. When 2 cm is installed it needs to go onto a plywood sub top for support. An additional strip of granite is then applied around the edge to hide the sub top, and make the edge appear thicker. It becomes 4 cm with the extra strip added. There is a seam where the strip is glued but typically it is not noticeable, inless the fabricator does a poor job. 3 cm is thicker and stronger so it does not require a sub-top nor the extra strip around the edge. There is no seam and the edge is 3 cm. Some people do not like the thicker look of the granite on the inside rim of an undermount sink. There are also difference supporting requirements for the 2 cm vs 3 cm overhang, such as for a bar area. I went with the 3 cm because I happened to fall in love with a particular slab. I am glad because I did not want the extra seam around the edge. O.K., Kevin, how'd I do?

First, I would question the professionalism of your installer. Underlayment is not the same as industrial grade PB, that being said, MDF or plywood would be a much better choice, and yes, I would use 5/8" material rather than the 1/2". Especially if you have Euro cabinets you will run into problems. Spanning the DW area should not be a problem, just make sure they don't put a joint close to that area. FYI Particle board comes in a number of different densities. This indicates how much wood and how much filler or adhesive is in the sheet. Industrial board is a 45 lb density, commerical board is 42 or less while some underlayment is less than 20 lb density. MDF is typically over 50lb density, and very stable, some are even exterior grade and water resistant. A contractor that buys based on price at a box store, is, in my opinion, not a professional. Good Luck !