2cm vs 3cm

Recently there has a been a lot of confusion about the thickness of granite counter tops. I hope this will be some help.

Previously, most installations of granite in the US used stone of approximately 2cm (3/4") thickness with laminated edgework detail of 4cm (1 ½") installed over a plywood substrate to ensure strength and durability.

Over the past decade the popularity of stone countertops has increased significantly; as a result many new fabricators have entered the industry with the desire to lower expenses and increase revenues as much as possible. This has created the demand for fast production and installations, eliminating the lamination process by reducing the apparent thickness at the edgework detail to only 3cm (1 1/8") by using a thicker and heavier 3cm (1 1/8") stone. In many cases these fabricators are selling these installations without recommending a plywood substrate.

Keystone Cabinet & Granite Outlet along with many other authorities in this industry do not recommend installations of 3 cm (1 1/8”) stone without substrates at least in the cook top, sink cutouts, and seam areas. Many custom fabricators, including Keystone Cabinet & Granite Supply, consider 2cm (3/4”) installations with proper substrates to be superior to 3cm (1 1/8") installations that are unsupported by substrates for the following reasons.

  • 2cm (3/4") granite properly adhered to a 5/8" or ¾" substrate has more tensile strength (flexibility) than 3cm (1 1/8") granite alone. Many fabricators falsely promote 3cm stones to be sturdier than 2cm stones because of the difference in thickness, misleading customers to believe this extra thickness creates extra strength. In actuality, 2cm coupled with a substrate is the superior product because of its ability to flex.
  • 2 cm granite seams are easily kept flat without creating a lip even if the stone is slightly warped because of its superior flexibility combined with substrate to bond resin at seams. Seams cannot be kept even with 3cm if stone is slightly warped because of it lack of flexibility and because most fabricators do not use a substrate to bond resin at seams.
  • Sinks and cook top cutouts are supported with substrates in the front and back of cutouts where the stone becomes narrower requiring flexible strength support. Substrates can be used to assist the attachment of sinks and cook tops with 2cm granite installed over substrate. Substrates allow extra support for a flat bar to be routed between stone and subtop if needed.
  • 2cm granite substrate distributes the weight over the cabinets, eliminating the possibility of fulcrum points at various spots of the cabinets. This allows more tolerance for the cabinet maker to level and keep the tops in the same plane, which is a necessity for superior countertop installation. 3cm unsupported granite is 1/3 heavier than 2cm. Unless the cabinets are perfectly level and on the same plane (in practice, normally not the case), any slight problem with levelness or out of plane conditions will cause fulcrum points at various locations on the cabinets and can cause shifting at seams and problems at cook tops and sink cutouts after a period of time. This will also produce an uneven butting of the granite countertop to the top of the cabinets making very unattractive gaps that can be detected with little investigation.
  • 2 cm granite with substrate allows overhang to extend up to 12" without support. Unsupported overhangs beyond 10” are not recommended with unsupported 3cm granite.
  • 2 cm splashes allow for more counter space compared with the 3cm splashes which create a much bulkier presentation and on standard cabinets may cause less counter space and placement of faucet holes above sinks.

    Keystone Cabinet & Granite Supply Outlet is not saying it's better to one from the other. We are just providing you with as much information as possible so you may make an inform decision.