Builders use both structural and non-structural plywood during construction. When it comes to your floor and your home, can you use non-structural plywood?
If you plan on using the non-structural plywood as indoor flooring, you’re in luck. You can use non-structural plywood as indoor flooring without much worry.
However, if you plan on using it as deck flooring, you’ll have to find another material because you shouldn’t expose non-structural plywood to moisture.
Now that we’ve got that out of the way, let’s go through the main differences between structural and non-structural plywood.
Structural vs. Non-Structural Plywood
During construction, almost all of the plywood you see in your home is structural.
That’s not only because it’s much stronger than the non-structural variety, but also because it can withstand exposure to moisture and changing temperatures.
Let’s compare the two types of plywood now.
The main difference between structural plywood and non-structural plywood is the type of glue used during production.
In the case of structural plywood, they use what’s called an A-bond glue. You’ll often see structural plywood labeled “exterior” or “exposure rated.”
You can make A-bond glue from phenol-formaldehyde resin, an extremely adhesive substance. It used to be a popular ingredient for constructing circuit boards, but newer adhesives have since taken its place.
A-bond adhesives work so well because of their ability to withstand changes in their environment. It is waterproof and can withstand temperatures as high as 428ºF.
With these attributes, it serves as a solid and durable building material.
Plywood that has B-bond adhesives is also considered structural plywood. B-bond glue uses a melamine resin, which is also water and weatherproof. A-bond is slightly better at keeping moisture out than B-bond, though.
Non-structural plywood uses either C or D-bond adhesives during its fabrication. C and D-bond adhesives are not waterproof, which is the another difference between structural and non-structural plywood.
You’ll often see non-structural plywood labeled “indoor.”
Both C and D-bonds use urea-formaldehyde (UF) adhesives. UF adhesives are firm but not moisture-proof. If you were to use non-structural plywood during construction, there’s a chance water could leak through, causing extensive damage.
C and D-bond adhesives also react negatively to changes in temperature. If you used this type of plywood for exterior uses, the glue would break down quickly, and you’d have to pay for costly repairs.
Which is Best for Flooring?
When most people talk about flooring, they mean the flooring inside their home. You can use non-structural plywood as indoor flooring because you should not expose it to changes in temperature that could deform the glue.
As indoor flooring, your plywood will also stay dry. Since you can isolate your plywood from both temperature changes and moisture, you’re safe to use non-structural plywood as flooring in your home.
Advantages and Disadvantages
Now that we know more about each type of plywood, let’s go through the advantages and disadvantages of each.
Advantages of Structural Plywood
- Weather and waterproof
- Certified for both indoor and outdoor use
- Suitable for trusses and other supporting structures
- Solid furniture material
Disadvantages of Structural Plywood
- More expensive than non-structural plywood
- Low-grade veneers
- Not good for finishings
Advantages of Non-Structural plywood
- Less costly than structural plywood
- Certified for indoor use
- Suitable for finishing work (including floors)
- High and low-grade veneers are available
- Paints and stains look great
Disadvantages of Non-Structural plywood
- You cannot use it outdoors
- Not as strong as structural plywood
- You can ruin it if exposing it to the elements or moisture in-house
Plywood has another classification aside from a structural or non-structural rating. When we talk about plywood grades, we mean the quality of the wood.
You’ll find that both non-structural and structural plywood comes in some of the same grades, but not all.
Grade A is the most finished plywood variety. It’s smooth and readily paintable. Grade A plywood cannot contain imperfections, and manufacturers must repair all gauges or knots before it can be sold.
No more than 18 repairs can be present on the plywood. Grade A plywood is best for finishings, like floors, baseboards, or furniture.
Grade B is the second-best quality plywood. Only knots measuring less than one inch across can be left on the plywood. You must make repairs with wood or synthetic materials. Grade B is paintable but not as smooth as Grade A.
Grade B plywood is suitable for any projects you’ll paint over.
Grade C (Plugged)
Grade C (plugged) plywood is middle-of-the-road quality stuff. It allows splits of up to an eighth of an inch wide, while knotholes can only be a half-inch wide. Some broken grain is acceptable.
Grade C plywood is best for hidden projects, like the back of a bookcase or the base of a set of drawers.
Grade C has slightly more imperfections than its sibling, the Grade C (Plugged). Knots can only be 1.5 inches wide, while knotholes can only be 1 inch wide.
Sanding and repair imperfections are allowed, as long as they do not impact the strength of the wood. Some limited splits are also allowed.
Grade C plywood is most commonly used during structural applications because it’s harder to paint than other varieties.
Grade D has the most physical imperfections of any grade of plywood. Knots and knot holes can be no more than 2.5 inches wide. Some splits are allowed, and so is stitching, under certain circumstances.
Grade D is almost exclusively used as structural plywood, meaning it’s hidden from view.
So, can you use non-structural plywood for flooring? Absolutely! Since most non-structural plywood is either Grade A or B, its intended purpose is to be seen.
One of the best ways to use this sort of high-grade plywood is to use it as flooring.
You can paint your plywood to fit the image of your perfect room.