Ryan Womeldorf has more than a decade of experience writing. He loves to blog about construction, plumbing, and other home topics. Ryan also loves hockey and a lifelong Buffalo sports fan.
How Much Weight Can Plywood Support? (Find Out Now!)
Plywood is not only one of the cheapest materials out there, it is also one of the most versatile as well. With the right application, plywood can make for a strong supporting material in various construction projects.
But just how strong is plywood? How much weight can plywood actually support? The thickness is the most important part. A 12-by-36-inch piece of plywood that is ¼-inch thick will only support about 5 pounds before it starts to bend. But a 12-by-36-inch piece of ¾-inch plywood can support 50 pounds easily.
Table of Contents
- How Strong is Plywood?
- The Other Characteristics Impacting Strength
- What Else Makes for Good Plywood?
- Related Questions
How Strong is Plywood?
Before we get into the thick of it with plywood and its real strength, we should know about the general strength it possesses. The determining factor behind the strength of plywood is in the thickness of the plywood.
The reason that it is so strong is because of how it is constructed. There are several layers of varying materials that have been bonded together under high pressures. These layers are then glued on top of one another.
Plywood also uses alternating grain patterns. By using alternating grain patterns, it gives the plywood increased strength. The result is that the plywood is stronger than a piece of wood of equivalent size in its natural state.
It is not uncommon for a ¾-inch thick piece of plywood to be able to support 50 pounds or more. Of course, a piece of plywood that is ¼-inch thick will only be able to support a few pounds at a time before bending.
The Other Characteristics Impacting Strength
The layering process is just one of the reasons why plywood can be so strong. Plywood is used in some applications where a heavy, strong piece of wood is required. Yet still, there are some projects that require a different type of plywood.
In concrete forms, industrial flooring, and stair risers, you need the strongest plywood available. For cabinet facing, however, you would not want to use that kind of plywood. Thankfully, versatility is one of the most important factors behind plywood.
There are a few other things that impact the overall strength levels behind plywood. That includes the thickness, layering, glue, and wood species. Let’s take a deeper look at the other characteristics of plywood.
Thickness of the Plywood
As we covered above, the thickness of the plywood is perhaps the most important characteristic. The thicker that the plywood is, the stronger that it will be. That is why one of the most commonly used thicknesses for plywood is ¾-inch.
When it comes to heavy-duty construction projects, 1-inch-thick plywood is typically the plywood of choice. There are also pieces that have tongue and groove patterns. Those patterns can then interlock together to provide additional strength and support.
Plywood that is only ¼-inch in thickness is not meant to support much weight. You can safely expect it to hold about 5 pounds before it begins to bend.
Layering of the Plywood
Plywood is made through a complex series of layering. A good way to determine the strength of the plywood being used is to look at the number of layers associate with that plywood. The cool thing is that you can count each of the layers by focusing on the edge of any of the pieces of plywood that you use.
The weakest plywood that you will find, called “shop-grade” plywood, has just 4 layers. Shop-grade plywood is also the most affordable plywood that you will find. That said, it is also more liable to bend and break than a piece of plywood that has several layers to it.
Moderate strength plywood will have anywhere between 4 and 7 layers to it. When it comes to moderate strength plywood, you can also use it for nearly any project that you can think of outside of industrial projects.
The strongest plywood that you can find has more than 7 layers to it. The strongest types of plywood would go into more specialized projects like router patterns or other industrial applications.
The Glue and Wood Species of the Plywood
One of the last characteristics that impact the strength of plywood is the type of wood species. Perhaps the most common wood species used in plywood is conifer. Conifer is the kind of wood species that make for softwood plywood.
Conifer plywood is not as strong as plywood that comes from one of the hardwood species. To overcome that weakness, some manufacturers will make use of exterior glue to give adhesion to the layers.
The exterior glue, when used on softwood plywood, can even make that softwood plywood stronger than its hardwood counterpart with some time. The glue keeps the plywood from taking on moisture. Moisture is what can cause the layers within plywood to separate, weakening the plywood over time.
Should the manufacturer use inferior glue on its softwood plywood, then it won’t be as strong as the hardwood plywood. While the thickness of the plywood is the greatest determining factor in the strength of plywood, the glue may be the most crucial component.
Shear Strength Matters
Finally, another major factor in quality plywood is its flexibility or shear strength. For example, when plywood is used as sheathing for a home, it has to be able to resist any cracking during the settlement process. Sheathing is generally placed over the 2×4 studs on the home’s exterior walls.
For the purpose of home sheathing, you would want to use plywood with a thickness of either ¾-inch or 5/8-inch thickness. That is because it has the flexibility required to stand up to cracking while it is in the settlement process.
What Else Makes for Good Plywood?
So, we know that alternating layers are important for the strength of good plywood. But there is more to the alternating layers than meets the eye. By alternating layers, it also adds stability to the plywood, making it less likely that the plywood reacts to things like moisture while also resisting shrinkage and expansion.
Plywood is commonly available in sheets, given that it is a manufactured product. Plywood sheets also come in a variety of thicknesses. Really, the size of the sheets all comes down to the application at hand.
For something like furniture or cabinet-building, you can also find plywood that has a smoother, finer veneer. That smoother veneer means that you can finish it in the same way that you would a non-manufactured, natural wood.
Now that we know more about the components of plywood, you may be left with more questions. Here are some of the most commonly-asked questions when it comes to plywood.
Is Plywood Strong Enough to Walk On?
Plywood is commonly used as attic flooring. That means it has to be strong enough to walk on. Thinner plywood is acceptable in this instance, particularly when it comes to joist spacing of 16 inches.
If you are planning to finish the attic flooring, turning it into a living area, then you would want to go with ¾-inch plywood. Thinner plywood has more flex to it when you walk on it, even when it has 16-inch spacing. The constant flexing from walking over it will eventually damage the flooring. That is why you would want to go for ¾-inch plywood in living areas or spaces with a lot of foot traffic.
How Do You Calculate the Load Capacity of Plywood?
For reference, plywood panels that are over ¾-inch in thickness typically require a special order product. That said, if you are looking to determine load capacity, then you would start by calculating the total area in question, multiplying by 50psf.
Typically speaking, however, you would want to consult a professional to determine the load capacity. The last thing that you want is to apply plywood to a certain application only to find out that it can’t handle the load.
Adhere to the maximum allowable loads for plywood and adjust the thickness wherever you need to. Remember, the greater the thickness of your plywood, the more tensile strength that it will have. Flexibility is important depending on the application involved.
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