Question 1

What is the difference between OSB2 and OSB3 flooring boards?

Accepted Answer

OSB3 is rated for structural use in humid conditions under EN 300, whereas OSB2 is only suitable for dry interior conditions. For subfloors, loft boarding or roofing decks where moisture exposure is possible, OSB3 is the appropriate choice and is widely specified by UK building regulations and warranties.

Question 2

Can T&G OSB3 be used as a finished floor surface?

Accepted Answer

OSB3 tongue and groove boards are intended as a structural subfloor rather than a decorative finish. They are designed to receive floor coverings such as carpet, vinyl, ceramic tiles or engineered flooring. The surface texture is not suitable as a standalone wear layer in occupied spaces.

Question 3

What joist spacing is 18mm OSB3 rated for?

Accepted Answer

18mm OSB3 T&G flooring boards are generally suitable for joist centres up to 600mm, which aligns with the 600mm board width so joints always fall on a support. For spans up to 450mm centres the boards perform well under standard domestic loading. Always confirm with your structural requirements and local building control where applicable.

Material	Oriented strand board (OSB)
Grade	OSB3 - structural use in humid conditions
Profile	Tongue and groove (T&G) long edges
Nominal Size	18mm (3/4 inch) x 600mm x 2440mm
Finish	Factory-sealed edges
Use Class	Structural - humid/load-bearing applications

Specifications

What it's used for

Fitting and handling

FAQ

Orientated Strand Board (OSB)

Tongue and Groove OSB3 Flooring Boards