Why Do People Add Plywood Under Their Countertops, And Do You Need To Do It?

If you're considering installing a quartz countertop, there's a good chance you've heard something about using plywood as additional support. However, don't run to the timber yard just yet, because plywood isn't always necessary. Quite the contrary, the odds of you needing plywood support are actually pretty slim. On the off chance you haven't heard about adding plywood to a quartz countertop, the logic is thus: Plywood adds extra reinforcement for frequently used surface areas. Reinforcement adds to the longevity of your countertop, which is a major plus whether the quartz countertops are for a rental property or your own home. 

So, why even question it, then? As it turns out, according to Caesarstone, whether plywood is needed for quartz countertops comes down to the thickness of the slab. If your countertop is 3 centimeters (or 1.18 inches) thick, it'll be strong enough on its own. And, given that the company notes that 3-centimeter slabs make sense for most people, that means in most cases, there's simply no need for plywood. Having said that, if you have opted for something thinner, there are a few other things to keep in mind.

While quartz countertops are typically 3 centimeters thick, that's not always the case. For starters, Kungfu Stone points out that that can depend on where you are in the world. In fact, the company says that in parts of Asia, 1.5 centimeters to 2 centimeters (0.59 inches to 0.78 inches) are more common. That said, even if you're based in a region where 3-centimeter quartz is most popular, you may still have opted for something thinner to save money.

Whatever the case may be, if your quartz countertops are on the thinner side, you may think you need to consider plywood. Once again, though, that's not a given. Kungfu Stone claims that anything from 1.5 centimeters is strong enough sans plywood support, and even Caesarstone notes that plywood for 2-centimeter countertops is only necessary in the case of overhangs. More specifically, Caesarstone's advice is to use plywood for overhangs that extend 8 inches or more. 

So, unless your quartz countertops are 1.3 centimeters (0.5 inches) thick or under, or stick out significantly, you don't need plywood. Go right ahead with your renovation, and unless you have a contractor specifically telling you otherwise, don't even give it another thought.

As an aside, it's worth noting that using plywood under thinner quartz countertops isn't necessarily a great idea, long term. In fact, most manufacturers recommend going for something thicker whenever possible. 

Case in point: Royal Stone Care's website warns that while thinner 1-centimeter (0.39 inches) quartz countertops are available as prefabricated options for those on a budget, they're often not terrific quality. Likewise, Caesarstone cautions that even 1.3-centimeter-thick countertops are incredibly delicate. Sure, plywood will help add some structure to that, but unless you're desperate to use quartz and this is your only option, it's best to go with something less precarious from the get-go. Save up and splurge on thicker quartz countertops when you can.

So, is plywood necessary under your countertops? In most cases, no. Even if you're picking something on the thinner side, most times, it's just an added step that will add to the height of your counters without much benefit. Of course, if you have large overhangs, that's something to keep in mind and it's never a bad idea to check in with a professional. However, as a general rule, plywood is only required for exceptionally thin quartz — and we wouldn't recommend trying that, anyway.