Installing Quartz Countertops

Home styles change over the years. While there are classic styles that stay with us forever and people who are specifically trying to capture the style of a particular era, that’s not the majority of people. Most people would rather go for something modern, following the trends of style, and have their home built or remodeled to whatever the current style is.

Much of the styling trend in kitchens has been in the countertop materials used. While there are always less common materials used, there have been trends through the years, with different materials becoming the most popular for a time.

Formica laminate became the most popular countertop material after the end of World War II and retained that coveted position for half a century. When Corian countertops came along, Formica lost its spot as the number one countertop covering. However, Corian’s superior durability and ability to sand it down and refinish it allowed Corian to take over from Formica in the 1990s.

At about the same time corian became popular, granite came along, competing with marble and other exotic materials. But the big advantage Corian had was cost. Over time, the trend has been more toward granite, becoming so popular that the major home improvement centers all offer it as an option.

In recent years, another competitor has replaced the trendsetter, quartz. Since about 2004, quartz has been climbing and is now considered the way to go. Slightly more expensive than granite, quarts are more expensive in the marble order, making it one of the more costly options. Today’s quartz countertops are engineered quartz, allowing for a much broader variety in appearance. Today’s engineered quartz countertops can take on the appearance of almost any mineral desired.

Quartz is a mineral, making it extremely hard and non-porous. That means it doesn’t scratch or stain, and unlike granite, the surface doesn’t have to be sealed.

Some people mistake engineered quartz countertops for corian, thinking they are the same, as they use a combination of minerals and polymers. However, Corian uses roughly 66% mineral content, with the rest being Acrylic plastic. Quartz, on the other hand, is over 90% mineral, with less than 10% rosins and polymers. In side-by-side comparisons, quartz looks more like real stone, while Corian tends to have an artificial look. But then, Corian never intended to look like a natural stone.

Quartz is commonly thought of as being heat-resistant and able to withstand temperatures up to 400°F. However, even though this is true, there is something called “thermal shock.” The rapid change of temperature caused by setting a hot pan or bag of ice on the counter could put enough strain on the material that it will cause cracking.

Quartz Countertop Thicknesses

Not all quartz countertops are equal; a lot depends on the thickness of the material. Manufacturers supply them in 1cm, 2 cm, and 3 cm thicknesses, with some replacing the 1 cm thickness with a 1.2 cm version. The various thicknesses attempt to reach potential customers at different price points.

The thinner quartz is only found in prefabricated countertops. Most of these come from overseas factories and have a laminated edge that has already been smoothed, making the countertop ready for installation. The “laminated edge” is made by cutting a thin strip of the same material as the countertop, gluing it to the bottom of the main body of the countertop, and smoothing the edge. This is also done at times with 2 cm countertops, giving them a 4 cm thick edge.

These thinner countertops always require a layer of plywood underneath them for support. The maximum distance the countertop material can span without support is 12”.

A grade of quartz is referred to as vertical quartz, which is essentially identical to the 1 cm countertop material. This thickness is fine for vertical applications, as it is always installed against plywood or drywall, which will support it.

Better quality prefab countertops use 2 cm quartz with or without a laminated edge. The added thickness means that the countertop can span up to 24” without support. A plywood backer is not required unless the countertop is going to span areas wider than that. But since most base cabinets are more comprehensive than 24”, it is usually a good idea to put a layer of plywood under the countertop. In this case, a laminated edge is used to hide the plywood.

Home builders looking to provide an upscale appearance while still controlling cost will often use 2 cm quartz to save money. This gives a high-end look while saving on overall material costs. Since most people don’t know the difference, they are able to get away with it.

However, the best quartz countertops are 3 cm thick. The added thickness provides a more massive appearance without resorting to a laminated edge. Due to the strength of the thicker material, plywood backing is not normally needed.

Installing Quartz Countertops

The bridge span between supports is the biggest thing to consider when installing quartz countertops. As mentioned in the last section, adding plywood support for spans over 24” is the norm.

But what about installing countertops with overhangs? Adding an eating area to a countertop or creating a wide countertop to provide extra work area, especially on islands, has become quite popular. But the material used has to be able to support it.

By and large, overhangs cannot extend more than 1/3 the total countertop depth without support, up to a maximum extension of 15”. Should a more significant overhang be desired, the addition of corbels will be required. These need to be designed to be appropriate to support the weight of the countertop and be attached to something that will provide the necessary structural support, such as a 2×4. The maximum spacing between corbels is 36”. With corbels, the countertop can have an overhang of up to 24”, but the overhang past the end of the corbels must still be less than 1/3 the total counter depth, with a maximum of 15”. Beyond 24”, the addition of posts is required, along with a whole plywood substrate. These posts cannot be more than 36” apart.

Before the new quartz countertops are installed, the existing countertops, sink, and stovetop (if installed) need to be removed. This also means disconnecting the sink plumbing, both the feed lines and the drain lines. The countertop is usually installed with clips, holding it to the base cabinets.

A stone countertop supplier will need to cut the new countertop. This is typically done using a template rather than just dimensions. If dimensions are provided, they usually don’t consider any curved areas in the wall or angles, which isn’t true. By making a template out of strips of Luan plywood glued together with hot melt glue, the exact size needed can be determined, allowing the fabricator to make the countertop fit exactly.

The actual cutting of the countertop, including cutting out for the sink and making a hole for the faucet, is done with a wet saw, making it impossible for most people to do it themselves.

Before installing the countertop, the top edge of the cabinets needs to be checked to ensure they are level and smooth. Any high or low points in the edge should be leveled out by cutting them down or shimming. If a plywood support is required, it should be installed before the countertop arrives.

The countertop is installed with either an acrylic adhesive or silicone caulking. The shop which prepared the countertop may have also glued some metal clips on the bottom of the countertop, allowing screws to be inserted, attaching the countertop in place while the adhesive cures. If a matching quartz backsplash is installed, it will also be installed with silicone caulking as the adhesive.

These countertops use an under-mount sink rather than one with a flange that overlaps the countertop on the top side. The under-mount sink provides a cleaner overall appearance while eliminating one of the biggest bacteria traps in the kitchen. The under-mount sink is installed with a combination of silicone caulking and clips, just as the countertop is.

The countertop and sink must be left for 24 hours for the adhesives to cure before use.