Description
Quick answer: OSB3 board is a strong, cost-effective structural sheet material for roofing, flooring, loft boarding, shed roofs, outbuildings and general building work. This square-edge OSB3 board is available in 9mm, 11mm and 18mm thicknesses. OSB3 is moisture resistant, not waterproof, so it should be stored dry and covered with a suitable finish or roof covering where exposed.
What is OSB3 board used for?
OSB3, or oriented strand board, is made from layers of wood strands bonded together to create a strong, consistent board. It is widely used for roof decking, shed roofs, garden buildings, floors, loft boarding, wall lining, boxing-in and general construction work.
If you need interlocking edges for a continuous deck, see our 18mm OSB3 Tongue & Groove Board. To compare the full category, browse OSB Boards & OSB3 Sheets.
Which OSB3 thickness should you choose?
| OSB3 board | Common uses |
|---|---|
| 9mm OSB3 | Lightweight boarding, lining, boxing-in and general sheet work where suitable support is provided. |
| 11mm OSB3 | A common option for shed roofs, garden buildings and roof decking where properly supported and covered. |
| 18mm OSB3 | Flooring, loft boarding, stronger roof decks, storage areas and jobs where a thicker, stiffer board is required. |
OSB3 for shed roofs and roof decking
OSB3 is commonly used for shed roofs and roof decking because it is strong, practical to cut and good value. 11mm OSB3 is often used for suitably supported shed roofs. 18mm OSB3 creates a stiffer deck for heavier-duty roof and floor applications.
OSB3 forms the deck rather than the finished waterproof layer. Cover roof decks with a suitable system such as felt, roofing membrane or EPDM. Browse Roofing Membrane & Shed Felt or EPDM Rubber Roofing.
OSB3 for flooring and loft boarding
18mm OSB3 is commonly used for flooring, loft boarding and storage decks where the board thickness, support spacing and loading are appropriate. With square-edge sheets, board joints should be properly supported. For an interlocking edge profile, choose the 18mm OSB3 Tongue & Groove Board.
Is OSB3 waterproof?
No. OSB3 is suitable for structural use in humid conditions, but it is not a finished waterproof board. Keep sheets dry before installation, avoid standing water, seal or protect exposed edges where required and use a proper weatherproof covering for roof applications.
OSB or plywood?
Choose OSB3 when you need a practical structural board for covered work such as roof decks, shed roofs, floors and lofts. Choose plywood sheets where face quality, grade choice, finish or a specific plywood specification matters. For more help, read OSB vs Plywood or Which Sheet Material Should I Use?.
Before ordering
- Thickness: choose the board to suit the job, support spacing and loading.
- Edge support: support square-edge sheet joints appropriately.
- Roofing: cover OSB3 roof decking with a suitable weatherproof roof covering.
- Expansion: allow suitable expansion gaps when installing larger sheet areas.
- Storage: keep sheets flat, dry and protected before installation.
Compare alternatives in Sheet Materials, Plywood Sheets and Chipboard Flooring.
