Description
Quick answer: 18mm OSB3 tongue & groove board is a strong structural sheet with interlocking edges for continuous decking across supported joists or rafters. It is well suited to flooring, roof decking, loft boarding and other structural deck applications. OSB3 is moisture resistant, not waterproof, so roofing applications must be covered with a suitable weatherproof layer.
18mm OSB3 T&G board size
- Thickness: 18mm
- Sheet size: 2400 × 600mm
- Edge: Tongue & groove
- Grade: OSB3
Where is tongue & groove OSB useful?
The interlocking edges help neighbouring boards align and create a continuous deck, making this board particularly useful across larger boarded areas.
- Flooring and subfloors
- Roof decking
- Loft boarding and storage decks
- Sheds, garden rooms and outbuildings
- General structural decking
Why choose T&G instead of square-edge OSB?
Square-edge OSB is ideal where board joints can be fully supported by joists, rafters or noggins. Tongue & groove OSB creates an interlocking joint between adjoining boards, which can make installation neater and more practical across decked areas. The board still needs to be correctly supported and fixed for the application.
Can 18mm OSB3 T&G be used for roofing?
Yes, where the roof structure and specification call for 18mm OSB3. It forms the roof deck rather than the finished waterproof layer, so it must be covered with a suitable roofing membrane, felt, EPDM or other specified system. Shop Roofing Membrane & Shed Felt.
Can it be used for flooring?
Yes. 18mm T&G OSB3 is suitable for many flooring and deck applications where the support spacing, loading and fixing method are appropriate. Allow suitable expansion gaps and follow the requirements of the project.
Before ordering
- Check joist or rafter spacing and the required board thickness.
- Support perimeter edges and board ends appropriately.
- Allow suitable expansion gaps.
- Use fixings suitable for OSB and the supporting timber.
- Keep boards dry and flat before installation.
Need standard square-edge board instead? View our OSB Boards & OSB3 Sheets. For more guidance, read OSB Board Questions Answered.