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15 Reviews

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18mm Structural OSB 3 Sterling Board 2440mm x 1220mm (8' x 4')

£19.80ex. VAT £6.64 per m2
£19.80ex. VAT
£6.64 per m2

Express Delivery

Tue 23 Jun

Standard Delivery

Wed 24 Jun

Order by 2pm tomorrow
  • 20hrs
  • 11mins
  • 31secs

Delivery & Returns Info
Bulk Prices
10+ sheets 20+ sheets 50+ sheets
£19.60ex. VAT £19.40ex. VAT £19.21ex. VAT
Coverage required
m
m
Based on your total area of m2 (inc. 10% wastage) - of these are required (actual coverage of m2)

We recommend purchasing at least 10% extra product to allow for errors, damages or obstacles

Express Delivery

Tue 23 Jun

Standard Delivery

Wed 24 Jun

Order by 2pm tomorrow
  • 20hrs
  • 11mins
  • 31secs

Delivery & Returns Info

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Delivery & Returns Information

Delivery charges vary by product category and order value. Items may ship from different suppliers and arrive separately, so delivery charges can be shown per part of your order at checkout.

Standard (Nationwide) Delivery

Core Products
Core
ORDER VALUE DELIVERY CHARGE
Under £300 ex. VAT £30 ex. VAT
Over £300 ex. VAT FREE

Core Delivery charges apply only when all products in an order that have equivalents are accepted as such. If even one product cannot be substituted with an equivalent, the entire order will not qualify for Core Delivery charges.

Timber & Sheet, Building Materials, Joinery and Gardens & Landscaping Products
ORDER VALUE DELIVERY CHARGE
Under £300 £20 ex. VAT
Over £300 ex. VAT FREE

Express Delivery

Express Delivery - Timber & Sheet, Building Materials, Joinery and Gardens & Landscaping Products
ORDER VALUE DELIVERY CHARGE
Under £300 £50 ex. VAT
Over £300 ex. VAT £35 ex. VAT

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How delivery works

We work with a nationwide network of trusted suppliers. Items in your basket may be supplied by different suppliers and delivered separately. Where this applies, you will see delivery charges shown at checkout for each part of your order. We always aim to group products from the same supplier to keep delivery costs as low as possible.

Delivery areas

Delivery charges apply to mainland UK, excluding: AB, CA, CF, DD, DG, EH, EX, FK, KA, KW, KY, IV, LA, LD, LL, ML, NP, PA, PH, PL, SA, SY, TR, TQ and TD.

If your address is in one of these areas, we will contact you before processing your order to confirm any additional costs. We do not currently offer delivery outside the UK mainland.

What to expect on delivery day

  • Deliveries are typically kerbside.
  • Please ensure someone is on-site to accept delivery. For heavier items, help with offloading may be required.
  • Many building materials arrive on large vehicles. If access is restricted, a specialist vehicle such as a HIAB may be required and could incur an additional charge.

Why delivery can cost more than typical parcel delivery

Building materials often travel on larger vehicles and usually carry fewer drops per run than parcel networks. That is why delivery charges can be higher than standard e-commerce shipping.

Returns

Returns depend on what you have bought and whether there is anything wrong with it. For full details on eligibility, timeframes, and exclusions, please see our full policy.

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Key Features

  • {{foundation}} Used in a variety of structural applications
  • {{water_drop}} Offers load-bearing performance in humid conditions

Technical Specification

Technical Specification
URN: 4003002
Application: Roofs & walls
Thickness: 18mm
Width: 1220mm
Length: 2440mm
Weight: 28kg
Sales Unit: Sheet
Sales Unit Coverage: 2.98m2
Grade: OSB3
Wood Species: Pine / Spruce
Edge: Square
Bond Class: BS EN300
Formaldehyde Level: E1 (low)
Country of Origin: Latvia

Product Overview

Structural OSB 3 Sterling board, measuring 2440mm x 1220mm (8' x 4') with an 18mm thickness.

Engineered from cross-laminated softwood strands and bonded with resin under heat and pressure, it delivers consistent strength and stability without knots or voids.


Certified to EN 300 OSB 3 for load-bearing performance in humid conditions, it serves as a practical and cost-effective alternative to plywood for many structural applications such as heavy flooring, robust roofing, and demanding joinery or construction work.

Features & Benefits

  • Structural classification: OSB 3 certified to EN 300, for load-bearing use in humid conditions.
  • BBA approved: Permits use in a wide range of commercial and domestic projects.
  • Void-free construction: Consistent strength with no knots or core gaps.
  • Cross-strand stability: Resists warping, splitting, and expansion.
  • Moisture performance: Reliable in humid environments, unlike OSB 2 (dry-use only).
  • Workability: Easy to cut, drill, nail, and sand with standard tools.
  • Board size 2440mm x 1220mm: Compatible with UK framing centres for straightforward fixing on standard stud/joist spacing.
  • Thickness 18mm: Heavy-duty board for flooring, roofing, and high-load applications.


Applications

  • Flat roof decking: Structural 18mm profile provides the rigidity required for GRP, EPDM, and felt roofing systems across joist centres up to 600mm. 
  • Timber frame sheathing: High-capacity 18mm boards provide essential racking resistance and load-bearing support for structural wall and floor panels. 
  • Site hoarding and security: 18mm thickness ensures a robust, impact-resistant barrier for secure temporary site enclosures and perimeter fencing. 
  • Shed and outbuilding flooring: High-density construction eliminates floor deflection under the weight of heavy garden machinery and workshop equipment. 
  • Concrete formwork and shuttering: High-strength board serves as a containment solution for foundations and walls where a textured concrete finish is acceptable. 
  • Mezzanine and storage platforms: 18mm thickness provides a certified structural deck for internal mezzanine levels and heavy-duty shelving in warehouse environments. 
  • Sarking and roof boarding: Used beneath primary roof coverings to provide a secondary moisture barrier and increase the overall rigidity of the roof structure.


Installation Guidance

  • Allow for expansion: Leave a 3mm expansion gap between all board edges and a 10mm gap at rigid wall abutments to accommodate natural movement.
  • Stagger the joints: Lay panels in a "brick-bond" pattern across supports to ensure structural loads are distributed evenly across the frame.
  • Support all edges: Ensure every board edge is supported by a joist, stud, or noggin to prevent deflection and maintain a level surface.
  • Apply correct fixings: Secure boards using galvanised nails or screws at 150mm intervals along edges and 300mm intervals on intermediate supports.
  • Seal cut edges: Coat all field-cut edges with a high-quality water-resistant wood sealant immediately to prevent moisture ingress and edge swelling.
  • Orient boards correctly: Install the long axis of the board perpendicular to the supporting joists or studs for maximum structural spanning strength.
  • Protect from weather: Cover installed boards with a waterproof membrane as soon as possible if the structure is not yet fully weathered.
  • Fixing distance from edge: Ensure all fasteners are driven at least 10mm from the board edge to prevent breakout and maintain pull-through resistance.
  • Surface painting: Use a high-quality solvent-based primer or dedicated OSB sealer before applying topcoats to prevent strand swelling, as detailed in our comprehensive guide to painting OSB.


Compliance & Performance

  • Standard: EN 300 OSB 3 classification, verified for structural use in humid environments.
  • Certification: BBA approved for quality and compliance in construction.
  • Bonding: High-pressure, resin-bonded layers provide long-term durability and resistance to delamination.
  • Veneer quality: Free from internal knots and core voids, ensuring consistent structural integrity across the board.
  • Important note: Colour and finish are representative only and may vary slightly as this is a natural product. Always ensure proper ventilation if using in enclosed spaces, though this board is manufactured to E1 low-formaldehyde emission standards.

Customer Reviews

5
4
3
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5/5 based on 15 reviews

I used these in a shed build. The boards were level and delivered to me on time.

Mark Evans on

Really pleased with the quality of these boards

Ken Heelings on

The service from Ciara was amazing from start to finish

Dave K on

All boards arrived in good condition, and the price was cheap.

Harry Jones on

Arrived on time and I would recommend them to anyone

Jemma Granger on

I'd recommend Materials Market. I had a positive experience, bought at good prices and the boards were a good spec.

Kate Ryman on

Managed to order these on short notice and I was really impressed with the quality of the boards. I'll be ordering from them again

Kieron Pratt on

I ordered these for my carpenter, the service was great - a big thank you to Ciara for arranging my order.

Sally Hall on

Great service and good quality boards that arrived, really happy all round

Ty Vine on

The boards arrived in a good condition. I used them in a shop for a big flooring project I had.

Jay L on

great for sub-floors

Kyle Rittenhouse on

good

Isaac Crandley on

Great price, and my dog loves the new bed I made using it.

Martin Chivers on

great

Lee O'Mann on

excellent

Ian Duncan on

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Questions and Answers

What is the difference between OSB3 and plywood?

Plywood is made from thin layers of wood veneer glued in alternating directions, while OSB3 (Oriented Strand Board) is made from compressed wood flakes and resin.

answer supplied by James Herbert on 23 October 2025

Can 18mm OSB3 be used for flat roofs?

Yes. It is strong enough to span roof joists and provides a stable, moisture-resistant base for waterproof membranes like EPDM rubber, GRP fibreglass, or felt.

answer supplied by James Herbert on 07 November 2024

Is 18mm OSB3 better than 11mm for flooring?

Yes, 18mm OSB3 is the standard minimum thickness for structural flooring. 11mm is not designed to support the weight of people, furniture, or equipment without snapping or sagging.

answer supplied by James Herbert on 03 July 2025

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