A primer on grades, composition, and exposure ratings
If you ever handled any kind of home improvement project, then you must have come across a piece of plywood. It’s one of the most common and handy construction materials anywhere. You can find its uses in the home, restaurant, shop, offices, and construction sites. Plyboard is common at all these places, but there is a slight difference in the quality, and it depends on the site where it is used. So, how to choose the right one for your next project? Here are a few basic yet useful guidelines to help you get going in the right direction.
First of all- What is Plywood?
Plywood is basically a combination of various thin sheets of wood veneer. Each sheet is manufactured to give it a particular set of strength, span, and appearance properties.
Most of the plywood veneers are rotary cut by peeling a thin, unbroken strip of wood from a horizontally rotating log. The next step includes cutting the veneer into pieces, grading and drying correctly before using it to assemble. Veneer is also made by slicing a big log along its length into several long thin strips. Those strips are further matched for best appearance. It is a more labor-intensive process ideal for those having more expensive hardwoods.
Softwood Plywood and Hardwood Plywood
After the veneers are properly cut, they are further coated with resin and pressed together under prescribed heat and pressure to form a solid sheet. Plywoods having graded and marine property, require some intense process. Like the resin used is formaldehyde treated to make it moisture proof. When manufacturing the interior plywood, urea formaldehyde is preferred owing to its low cost. To give the plyboard a perfect balance, an odd number of veneer layers are used, usually five, seven, nine.
The more layers a sheet has, the more each veneer layer overlaps. The overlapping pattern creates a chance of potential defects in the other layers. Taking two distinct sheets of equal thickness, the one having more layers will possess a higher strength rating.
The sheets are further pressed at a prescribed pressure and trimmed into uniform sizes. Usually, the most common size is 4 feet by 8 feet, and the standard thickness is 1/8 to 1 1/4 inches.
Softwood plywood grades
The plywood we use for home improvement and construction project is categorized as softwood plywood. It signifies that the front and back veneers are made from softwoods like pine, cedar, douglas fir.
All the plyboard sheets are assigned a particular number among A, B, C, D. The letter highlights the grade and range, A being the highest and D being the lowest.
Grades and What They Mean
A: Means Smooth and Paintable– Wood or synthetic repairs are allowed. It can be used where there are less-demanding applications or for natural finishes.
B: Means Solid surface– Wood or synthetic repairs are allowed. Even some minor splits are also permitted.
C: Means Plugged and Tight Knots– Some broken grain is permitted. However, Discoloration and sanding defects don’t hamper the strength.
D: Means Knots and Knotholes– Limited splits are allowed. Moreover, stitching is also permitted.
Few other common grade combinations include AC, CC Plugged, and CD. Letter X is assigned to plywood intended for exterior use. Suppose a ply board rated CDX would carry one C face, one D face, and exterior-rated glue.
Softwood plywood is rated from one of four exposure ratings. It highlights the durability when the ply board is exposed to moisture.
Exterior: This indicated the plywood has a fully waterproof glue joint. It is intended to use in areas that are constantly exposed to moisture or weather.
Exposure 1: It carries a fully waterproof bond. It is specially designed for exposure to weather and moisture before they are fully covered.
Exposure 2: These graded ply boards are subjected to use where there is controlled moisture and weather conditions.
Interior: These types of plywoods are strictly to use in protected interior conditions.
Hardwood plywood grades
Plywood also contains hardwood veneer faces. It is used in furniture, cabinets and various other projects where appearance play an important role. Even hardwood ply board has softwood veneer inner piles. Apart from that, they have an inner core of lumber, particleboard or various other types of materials.
The dimension of the hardwood plywood sheet is similar to softwood plywood. The hardwood ply board also comes in a size of 5 feet by 5 feet, that’s used in designing cabinets. When thickness comes into account, they are less uniform than the softwood plywood. It happens due to thinner veneers and the required number of sheets which needs to be imported from different countries.
Hardwood plywood carries a slightly different grading system. A-D grades (best to worst) applied to face of the plyboard sheet. And 1-4 is assigned to the back of the sheet. So, a plyboard carrying A-1 tag would have a good grade of veneer on the front and back. An A-4 will have a good grade on the front, but it will carry knots, blemishes, and repairs at the back.
Hope so, you will now find it easy to identify the best grade and quality of any plywood you come across.
If you have any requirements (bulk or retail) of plywood- whether softwood or hardwood, then all you have to do is send an email with your requirements at email@example.com or firstname.lastname@example.org.