Marine Plywood: A Comparison With General Exterior Plywood

Marine plywood is the premium quality exterior plywood . In order to understand marine plywood well, it’s better to make a comparison between marine plywood and general exterior plywood .

The following is the comparison between marine plywood and general exterior plywood :

1. The glue
The glue for marine plywood should be the best permanent WBP(phenolic) glue . But there are more types of WBP glue for general exterior plywood .

2. The grade of solid wood face/back veneer (see *Note 1 in the end of post)
No defects (except sound pin knots) are allowed on the face/back of marine plywood . But some defects are allowed on the face/back of low grade (such as C/D grade) general exterior plywood .

3. The thickness of solid wood face/back veneer
For marine plywood : According to marine plywood standard BS 1088 , the thickness of face/back veneers for multi-ply construction should be 1.3 ~ 3.8 mm; for three-ply construction, the thickness should be about 0.5mm .
For general exterior plywood: The thickness of face/back veneers can be reasonably thinner for cost-saving .

4. The core veneer
For marine plywood : Usually, each core layer of long grain should consist of only one piece of core veneer . Edge joints are allowed . End joints are prohibited .
For general exterior plywood: Each core layer can consist of several pieces of core veneers . Both end joints and edge joints are allowed .

5. The species of wood
For marine plywood : The species should be hardwood of high density .
For general exterior plywood: The species can be hardwood of high density, MLH (Mixed Light Hardwood) and so on .

6. The application
Marine plywood is intended for boat-building or other marine applications, aircraft construction . Marine plywood can also be used in construction. Marine plywood can be used for all the jobs which can be done by exterior plywood .
General exterior plywood is intended for indoor or outdoor application where resistance to weather/water is required .

Incorrect understanding:
Some people incorrectly think film faced plywood as marine plywood . In fact, the inner quality of marine plywood is much better than that of general film faced plywood . Marine plywood and film faced plywood have different meaning .

*Note 1 :
The face/back of marine plywood can also be MDO, HDO, or other weather/water resistant film paper .