Question 1

What is the difference between P5 and standard chipboard flooring?

Accepted Answer

P5 chipboard is manufactured with a moisture-resistant resin binder, making it significantly more tolerant of site moisture during construction than standard P4 or plain chipboard. It is less likely to swell at the edges if exposed to temporary dampness, though it is not waterproof and should not be left permanently wet.

Question 2

Should I use 18mm or 22mm P5 chipboard for my floor?

Accepted Answer

For most domestic upper floors with joists at 450mm centres, 18mm is generally sufficient. Where joists are at 600mm centres, or where the floor will carry heavier loads such as in a loft conversion used as a habitable room, 22mm is the recommended choice for additional stiffness and load distribution.

Question 3

Can P5 chipboard flooring be used in a loft conversion?

Accepted Answer

Yes. P5 tongue and groove chipboard is widely used in loft conversions across the UK as the structural floor deck. The interlocking T&G profile spreads loads across adjoining boards and reduces squeaking over time, making it well suited to habitable loft rooms. Always check that your joist sizing and spacing meet building regulations for the intended use.

Material	Chipboard (particle board)
Grade	P5 to EN 312
Treatment	Moisture-resistant binder throughout
Profile	Tongue and groove on long edges
Nominal Size (18mm)	18mm x 600mm x 2400mm
Nominal Size (22mm)	22mm x 600mm x 2400mm
Finish	Sanded face

Specifications

What it's used for

Fitting and handling

FAQ

P5 Tongue and Groove Chipboard Flooring 22mm x 600mm x 2400mm