The plies rules only applies to Chinese hardwood faced plywood, especially poplar core plywood. Chinese plywood mill use thin plywood veneers as basic material for production. The other countries of plywood production are Malaysia, Indonesia, Vietnam, Chile, New Zealand, Canada, Russia, Latvia and Unites States. Material used outside China are pine, birch, meranti, etc. These veneers are different with poplar veneer. So the number of plie rules don’t apply to plywood produced outside of China.
In the old days, people use 3-ply or 5-ply to name plywood because most of the plywood was made with three or five layers of veneers. In this page, we will talk about the number of plies in a hardwood faced plywood with poplar core. This will help if you decide to import plywood from China.
Odds Number of Plies
In a plywood sheet, there is usually an odd number of plies, so that the sheet is balanced. The balance warping. Because plywood is bonded with grains running against one another and with an odd number of composite parts, it has high stiffness perpendicular to the grain direction of the surface ply.
So the plywood is 3 plies, 5 plies, 7 plies, 9 plies, 11 plies, etc. There is also 4 plies for thin plywood but it is very rare. For thickness plywood like 18mm there are usually 13 or 15 plies.
Plies number in each thickness
This list only applies to Chinese plywood. It doesn’t apply to Malaysian or Chilean plywood because much thicker veneers are used by manufacturers in Malaysia and Chile.
|Number of Plies (including face veneers)|
|3.6||3 or 5|
|5.2-6.5||5 or 7|
|9||7 or 9|
|12||9 or 11|
|15||11 or 13|
|18||13 or 15|
|21||15 or 17|
|25||17 or 19|
3.2mm plywood with 3 plies
9mm plywood with 7 plies
18mm plywood with 13 plies
Calculate Ply Layers by Thickness
Number of Plies will increase 2 plies when plywood thickness increases 3mm. For example, 18mm plywood has 13 plies. Then 25mm (18mm + 3mm x2) will have 13 plies + 2x2plies = 17 plies.
Compare 18mm with 13 plies and 15 plies
|Specifications||18mm with 13 plies||18mm with 15 plies|
Minimum number of plies in plywood is 3 plies including face and back.
Not always. 4-plies plywood exists when the four layers are well balanced by manufacturers.
Plywood with more layers are more stable and stronger.