What is WBP plywood?

WBP plywood is a high-grade veneer plywood made with waterproof glue. It differs from marine plywood in terms of core clearance requirements.
In the plywood industry, the term WBP stands for Weather and Boil Proof rather than Water Boil Proof.
Water boiling proved easy. Many standard priced plywood boards can easily pass 4 hours of water boiling or 24 hours if the board is pressed well. Weatherproofing is more difficult as it requires the plywood to be wet and dry in intervals to simulate rainy weather.
The most important feature of WBP plywood is weatherproofing. WBP plywood holds up well in the sun and rain.
WBP plywood made of phenolic/melamine glue
Plywood is constructed of three or more thin sheets of wood (called veneers) glued together, with each layer laid at right angles to the grain of the next. Each plywood is composed of an odd number of veneers. The cross-hatching of the wood grain makes plywood stronger than planks and less prone to warping.
WBP plywood is one of the most durable plywood types. Its glue can be melamine or phenolic resin. To be considered exterior grade or marine grade, plywood must be produced with WBP glue. The best WBP plywood should be made with phenolic glue.
WBP plywood made with regular melamine instead of phenolic will hold up to lamination for 4-8 hours in boiling water. High-quality melamine glue can withstand boiling water for 10-20 hours. Premium phenolic glue can withstand boiling water for 72 hours. It should be noted that the length of time the plywood can withstand boiling water without delamination also depends on the quality of the plywood veneer.
WBP is designed for external use
Most sources refer to WBP as Water Boiling Proof, but this is somewhat incorrect. WBP actually developed the standard in the UK and is specified in British Standards Institution Standard 1203:1963, which identifies four classes of plywood glues based on their durability.
WBP is the most durable glue you can find. In descending order of durability, other glue grades are cook resistant (BR); moisture resistant (MR); and internal (INT). Properly formulated WBP plywood is the only plywood recommended for exterior use, according to the Food and Agriculture Organization of the United Nations. WBP plywood is designed for outdoor use such as house construction, shelters and covers, roofs, container floors, concrete formwork and more.
What is waterproof plywood?
Even though people use the word a lot, there is no waterproof plywood. “Waterproof” generally means that the plywood has a permanent phenolic bond that won’t deteriorate in wet conditions. This will not make the plywood “waterproof” as moisture will still pass through the edges and surfaces of the planks.