-
SaleBuy in Bulk & Save
26-49 50+ £18.38£22.06 £18.00£21.60 
18mm SmartPly OSB 3 Board 2440 x 1220mm (8′ x 4′) FSC®
18mm Smartply OSB3 is an engineered, load-bearing wood-based panel product, free of knots and voids, and suitable for structural use in humid situations.
Original price was: £19.79 Ex VAT (£23.75 Inc VAT).£18.95£22.74Current price is: £18.95 Ex VAT (£22.74 Inc VAT). Ex VATInc VAT Add to cart -
Buy in Bulk & Save
51-101 102+ £10.54£12.65 £10.32£12.38 
18mm Kronobuild OSB 3 TG4E Tongue And Groove Flooring Board 2440 x 590mm (8′ x 1.94′) FSC®
18mm OSB 3 with Tongue and Groove profiling is versatile, BBA approved and water-resistant timber panel suitable for load-bearing roofing and flooring applications in dry and humid conditions.
£10.75£12.90 Ex VATInc VAT Add to cart -
Buy in Bulk & Save
25-49 50+ £10.65£12.78 £10.43£12.52 18mm EGGER OSB 3 TG4E Tongue And Groove Roofing Board 2400 x 600mm (8′ x 2′) FSC®
18mm EGGER OSB 3 with Tongue and Groove profiling is versatile, BBA approved and water-resistant timber panel suitable for load-bearing roofing and flooring applications in dry and humid conditions.
£10.98£13.18 Ex VATInc VAT Add to cart -
SaleBuy in Bulk & Save
24-47 48+ £44.00£52.80 £43.09£51.71 
18mm EGGER Fire Retardant OSB 3 Flammex Board 2440 x 1220mm (8′ x 4′) FSC®
18mm Egger Fire Retardant Flammex OSB3 Board has flame-retardant intumescent coating and UV coating applied on one side. It can be used for exterior/interior walls and roofs.
Original price was: £46.67 Ex VAT (£56.00 Inc VAT).£45.36£54.43Current price is: £45.36 Ex VAT (£54.43 Inc VAT). Ex VATInc VAT Add to cart
Our specialist stores
Our specialist stores
18mm OSB
18mm OSB is a strong, solid wood based sheet made from pressed timber strands. It gives builders a reliable board that feels firm under load and works well in floors, walls and roofs. An 18mm OSB board is chosen when a project needs steady support, simple handling and a sheet that stays stable once fixed.
What is OSB board 18mm
OSB board 18mm is a strong panel made from thin wood strands pressed together. The strands sit in planned directions so the sheet stays firm, steady and ready for real construction work. This makes the 18mm OSB3 board suitable for real working jobs like decking out a floor frame, sheathing timber walls or creating rigid surfaces in everyday construction. OSB sheets 18mm give consistent strength, good screw holding and a smooth base for further finishing.
What is 18mm OSB used for?
18mm OSB is a dependable sheet used across many structural and practical jobs on site. Builders choose an OSB board 18mm for decking over joists and for creating a solid floor base in new builds or extensions. It also performs well for sheathing timber frame walls and lining internal partitions when a rigid panel is needed. Roof decking is another common use, as OSB sheets 18mm give a stable base under felt or membrane. In lofts, 18mm OSB creates firm flooring and useful storage platforms.
For everyday setups, an OSB 18mm panel suits garages and workshops as backing boards for tools. It is also strong enough for temporary site hoardings. And it works well as a simple barrier on busy sites. Outside, 18mm OSB3 is often used for garden sheds and small outbuildings, giving walls and floors reliable strength.
Types of 18mm OSB
18mm OSB comes in several useful options to suit different parts of a build. The standard sheet is the OSB3 18mm square edge, a simple and reliable panel used for walls, roofs and general decking. It also comes in the well known osb3 18mm 2440x1220mm (8’ x 4’) size that fits most site layouts.
For flooring, many people choose the tongue and groove version. These boards lock together neatly, helping create a smooth, even surface for loft flooring or floor decks.
A primed option is also available. Sold as 18mm OSB3 SiteProtect, it has a ready coated face that makes hoardings and temporary barriers easier to paint and finish.
18mm OSB3 also comes in a wide choice of sheet sizes to match different spaces. Full boards are available in the classic 2440 x 1220mm (8’ x 4’) format, while narrower options like 2440 x 600mm (8’ x 2’), 2440 x 595mm (8’ x 1.95’) and 2440 x 590mm (8 x 1.95’) work well in tighter areas or when you want less cutting. Compact panels such as 1220 x 300mm (4’ x 1’) are useful for loft hatches, small repairs or detailed internal work.
All 18mm OSB3 sheets follow BS EN 300 and carry CE2+ marking. They meet E1 formaldehyde level, are rated Euroclass D-s2,d0 for fire performance and include moisture resistant options for areas that may face brief dampness. Available in FSC where the FSC mark is displayed on product name. With these choices, it is easy to select the osb3 board 18mm that fits your project.
Benefits of 18mm OSB
- Strong board suitable for flooring, roofing and general wall work.
- Works reliably in humid building conditions thanks to its OSB3 rating.
- Fixings hold securely, making the board dependable for everyday tasks.
- The surface is neat and ready for light finishing when required.
- Provides a firm layer for roof builds, including pitched areas under tiles or slates.
- Tongue and groove boards slot together cleanly for smoother floor joints.
- Easy to move and position on site, especially in loft-panel sizes.
- Manages short-term moisture during installation without issues.
- Primed sheets can be painted quickly for hoardings and other temporary structures.
Why choose our OSB 18 mm?
Buying OSB 18 mm from Sheet Materials Wholesale is simple and clear. We keep this board in UK stock. If your project requires a larger quantity, you can request bulk or pallet pricing and receive a quick and transparent quote.
Delivery is straightforward. We supply the whole UK and bring your order directly to your site or home. Each order includes tracking and a VAT invoice, which helps both trade and DIY customers organise their work with confidence.
Many sizes are available for fast dispatch, with next day delivery offered on selected items. Every board arrives well packed and ready to use. We also make ordering flexible. You can buy a single sheet for a small project or choose pallet quantities for larger builds.
Choose the OSB 18 mm sheets you need, place your order online and enjoy fast delivery, including next day on selected sizes.
At Sheet Materials Wholesale, you can purchase 18mm OSB at low wholesale prices with fast nationwide delivery for most of items within 1-3 working days across the UK. Next-day delivery is also available on most orders. Competitive rates guaranteed.
FAQ
Where to buy 18mm OSB?
You can buy 18mm OSB online at Sheet Materials Wholesale. We keep UK stock, show clear pricing on each product page and deliver directly to your home or site across the UK.
What size screws for 18mm OSB?
For fixing 18mm OSB, screws around 50–60 mm are commonly used. They give a secure hold into joists or studs and keep the sheet stable during installation.
How much is 18mm OSB board?
Prices for 18mm OSB start from around £10 for t&g board and £17 for 8x4 board. To check the exact price, view the product page or request a quick quote online.
How much does 18mm OSB weigh?
A standard 18mm OSB sheet weighs from around 13.75 kg. Check the product listing if you need exact figures.
