• Plywood: Plywood is an extremely popular engineered wood product made from thin veneers of softwoods or hardwoods laminated together in alternating layers for strength and stability. Each layer is bound together using a strong adhesive. Common softwoods used to manufacture plywood include Douglas Fir, Pine and Spruce. Plywood sheets are graded from A – X on both faces, with different grades being suitable for different applications. (see also Decorative Surfaces and Panels for Packaging for other examples of uses for Plywood). You can find out much more about Plywood in our Merchant Guide to Selling Timber.
• Oriented Strand Board (OSB): OSB is a structural sheet material often used as an alternative to plywood. OSB is manufactured from engineered wood strands bonded together with resins under heat and pressure. It is produced in a number of different technical classes, defined in British Standard BS EN 300, which confirms its suitability for different end uses.
• Particleboard: Also known as Chipboard, Particleboard is made from woodchips / particles sourced from new and recovered or reclaimed sources which are mixed with resin, compressed and dried. It is available in different forms such as three-layer, moisture-resistant and cement-bonded. The load bearing technical classes are most common in construction applications such as P5 T&G flooring grade particleboard.
• Fibreboards: Are an increasingly important set of constructional wood based panels in the UK. Made from wood fibres the range of products goes from softboards and wood fibre insulation, to an increasing variety of medium boards and medium density fibreboards (MDF) through to high density panels such as hardboard.

Plywood: Three Glue Bond classes are defined within standard BS EN 314 part 2.

• Class 1 For Dry applications,
• Class 2 for High Humidity environments
• Class 3 for Exterior where moisture levels will be significantly higher than those encountered in Class 2.

OSB: OSB Standards are set out in BS EN 300 as follows:

• OSB2: for use in structural and non-structural applications in dry conditions only. It is not suitable for wet or humid conditions or where water may leak, e.g, near pipework
• OSB3: for internal structural use in dry and humid conditions, and where it may get an occasional wetting, e.g, flooring and wall or roof sheathing. It is moisture-resistant but not suitable for shower rooms or wetrooms. Specialist OSB3 products are available for dry-lining and for PassivHaus buildings
• OSB4: is stronger and more moisture resistant, making it suitable for heavier loads; modern methods of construction and timber frame building
• Pre-painted OSB: suitable for site hoardings (check manufacturer’s information)
• FR OSB: OSB board where a flame-retardant treatment has been incorporated during the board’s manufacture.

Particleboards: Technical Classes of Particleboard are defined in BS EN 312 (see Standards below).

• P1: General purpose boards for use in dry conditions
• P2: boards for interior fitments (including furniture) for use in dry conditions
• P3: non-load-bearing boards for use in humid conditions
• P5: load-bearing boards for use in humid conditions, most commonly seen as T&G Particleboard flooring
• P6: heavy duty load-bearing boards for use in dry conditions, most often used as a specialist

Fibreboards: Technical Classes are defined in BS EN 622 series of standards as below

• EN 622-2, Fibreboards | Specifications | Part 2: Requirements for hardboards
  o HB a general-purpose hardboard for use in dry conditions
  o HB.H a general-purpose hardboard for use in humid conditions
  o HB.E a general-purpose hardboard for use in exterior conditions
  o HB.LA a loadbearing hardboard for use in dry conditions
  o HB.HLA1 a loadbearing hardboard for use in humid conditions
  o HB.HLA2 a heavy-duty loadbearing hardboard for use in humid conditions
• EN 622-3, Fibreboards | Specifications | Part 3: Requirements for medium boards
• EN 622-4, Fibreboards | Specifications | Part 4: Requirements for softboards
  o SB General purpose, dry
  o SB.H General purpose, humid
  o SB.E General purpose, exterior
  o SB.LS Load-bearing, dry
  o SB.HLS Load-bearing, humid
• EN 622-5, Fibreboards | Specifications | Part 5: Requirements for dry process (MDF) boards
  o MDF – General purpose boards for use in dry conditions
  o MDF.H – General purpose boards for use in humid conditions
  o MDF.LA – Load-bearing boards for use in dry conditions
  o MDF HLS – Load-bearing boards for use in humid conditions
  o L-MDF – Light MDF boards for use in dry conditions
  o L.MDF.H Light MDF boards for use in humid conditions
  o UL1-MDF – Ultra-light MDF boards for use in dry conditions
  o UL2-MDF – Ultra-light MDF boards for use in dry conditions
  o MDF.RWH – Rigid underlays in roofs and walls

In terms of reaction to fire most wood based construction materials will be inherently Class D. This is an appropriate class for bio-based construction products and makes them suitable for most applications within a building.  Fire-retardant (FR) Constructional Wood Based Panels are largely the same as Constructional Wood Based Panels (see above) but have had a fire-retardant material incorporated during manufacture or as a treatment applied post manufacture to significantly boost the panel’s reaction to fire to Class C or B (see Standards for Fire Safety below). These products are more appropriate where a specific reaction fire classification is required.

More information is available through our fire related resources