A second option is Marine Grade Plywood (MGP), another engineered wood that takes thin layers of wood veneer, most commonly Douglas Fir or Okoume, and adheres them together using a water and boil proof (WBP) glue. Marine Grade plywood is considerably more expensive than standard OSB. Some of our customers choose to go with Marine Grade Plywood over OSB in high humidity areas where the walls will be pierced or penetrated in the field to add additional equipment not installed during production. Others prefer to have Marine Grade plywood in the base flanges where the shelter will be secured. Since all the wood used in the construction of our prefabricated shelters is encapsulated within fiberglass, we typically recommend OSB over Marine Grade to avoid unnecessary costs. However, the final choice of wood used is always up to the client.