P5 is a load-bearing particleboard grade for use in humid conditions under the relevant product standard. It resists occasional construction humidity better than a dry-use board, but it is not waterproof.
Moisture-Resistant Structural Boards for Floor Builds
Tongue-and-groove chipboard flooring forms a continuous deck over timber, engineered wood or approved metal joists. MacBlair stocks structural flooring boards for new builds and refurbishment, with profiled edges that locate neighbouring sheets and help distribute loads across joints. Select thickness and grade from the joist spacing, service conditions and floor design.
P5 flooring boards are intended for load-bearing use in humid conditions, including protected construction where occasional moisture may occur. They are not waterproof and should be installed, glued and protected in line with the board system. Match the deck to floor joists and structural timber specified below it.
Stagger end joints, provide perimeter movement space and support joints as required. Adhesive and mechanical fixing instructions vary by system, so follow the manufacturer rather than mixing methods. Floor insulation products and other building materials for floor construction must suit the same loading and moisture strategy.
Chipboard Flooring FAQ's
Thickness depends on joist spacing, loads and the approved flooring system. Check the structural plan or manufacturer span table, because a thicker board cannot compensate for unsupported joints or excessive joist spacing.
Many flooring systems require adhesive in the tongue-and-groove joint and may also specify adhesive on joists. Use the compatible adhesive, bead size and fixing method stated by the board manufacturer.
Leave the perimeter and intermediate movement provision stated in the installation guide. Room size, board moisture and floor layout affect where movement gaps are needed, so do not force the deck tightly between walls.
Standard P5 boards should be protected from prolonged or repeated wetting. If temporary exposure is expected, choose a system specifically approved for those conditions and follow its sealing, cleaning and drying instructions.