Tongue and groove flooring class P5 or P6

[Peter_K]

Feeling a bit unsure about what to buy. Reading the brochure "Build the Bathroom Right" and it says to use "moisture-protected chipboard floor panels with recommended class P5." On Bauhaus's website, it says their boards are "Forestia Floor are chipboards manufactured according to class P5 and P6," but they cost the same as regular ones, while Byggmax has one they call Moisture-resistant Floor Chipboard for double the price. I'm going to lay reinforcement mesh, water-based underfloor heating, and 20-40 mm of screed.

 

[Peter_K]

Another question, the boards are to be laid in a staggered pattern but my bathroom is 240 in width and 180 deep so it's possible to lay 3 boards without cutting, but it might not be as strong?