# WPC glossary: 100 terms, materials, methods and standards Canonical: https://woodplasticcomposite.net/guides/wpc-glossary-terms-standards/ Language: en Updated: 2026-10-17 Version: 1 Review: AI-assisted English article. Human technical review has not been recorded. ## Summary Understand WPC terminology for composite decking, cladding and fencing: materials, manufacturing, installation, testing and environmental evidence. ## Definitions and material structure Wood–plastic composite (WPC) — A material combining wood particles or fibres with a polymer. The formulation and finished profile determine performance; WPC is not a quality grade. Names and abbreviations: wood-polymer composite; woodfiber-plastic composite. [1, 2] Natural fibre composite (NFC) — A composite containing natural fibres or particles in a matrix. NFC is broader than WPC: flax, hemp and agricultural fibres need not contain wood. Names and abbreviations: plant-fibre composite. [1, 2] Wood–thermoplastic composite (WTC) — A wood-filled composite with a thermoplastic matrix that softens when heated. The name excludes cured thermoset systems. Names and abbreviations: wood thermoplastic. [1, 2] Composite material — A material made from distinguishable constituents working together. “Composite” alone does not identify the resin, reinforcement or suitable application. Names and abbreviations: composite. [1, 2] Matrix — The continuous phase surrounding the filler or reinforcement. Its chemistry influences processing, temperature response and moisture behaviour. Names and abbreviations: polymer matrix; binder phase. [1, 2] Thermoplastic — A polymer that softens on heating and hardens on cooling. Repeated processing can degrade it; remeltability does not guarantee practical recyclability. Names and abbreviations: melt-processable polymer. [1, 2] Thermoset — A polymer system forming a cured network that cannot simply be remelted. Phenolic and epoxy systems differ from ordinary thermoplastic decking. Names and abbreviations: crosslinked resin. [1, 2] Compound — A prepared blend of polymer, filler and additives. It may be supplied as pellets or processed directly into a product. Names and abbreviations: composite compound. [1, 2] Filler — A dispersed ingredient modifying cost, processing or properties. A filler may improve stiffness without improving every strength or impact measure. Names and abbreviations: particulate filler. [1, 2] Reinforcement — A constituent used to improve selected mechanical properties. Fibre length, orientation and bonding determine how effectively loads are transferred. Names and abbreviations: reinforcing fibre. [1, 2] https://woodplasticcomposite.net/guides/wpc-glossary-terms-standards/#glossary-group-1 ## Fibres, fillers and core polymers Wood flour — Finely ground wood particles. Particle-size distribution, species and moisture matter; wood flour is not identical to long reinforcing fibres. Names and abbreviations: wood powder. [1, 2] Wood fibre — An elongated wood-derived component. Fibre damage during compounding can reduce its aspect ratio and alter reinforcement efficiency. Names and abbreviations: wood fiber. [1, 2] Natural fibre — A fibre of natural origin; here mainly wood, flax, hemp or other plant material. Natural origin does not establish composite biodegradability. Names and abbreviations: plant fibre; natural fiber. [1, 2] Cellulose — A structural polysaccharide in plant cell walls. Its hydroxyl-rich surface contributes to water affinity and challenges bonding with nonpolar polymers. Names and abbreviations: cellulosic fibre component. [1, 2] Lignin — A complex plant polymer associated with cell-wall rigidity. Its behaviour differs from cellulose and influences wood chemistry and weathering. Names and abbreviations: wood lignin. [1, 2] Rice husk — The protective covering of rice grains, usable as a composite filler after preparation. Its silica content distinguishes it from ordinary wood flour. Names and abbreviations: rice hull. [1, 2] Aspect ratio — The ratio of particle or fibre length to its transverse dimension. Higher values can assist reinforcement, but dispersion and processing damage also matter. Names and abbreviations: length-to-diameter ratio. [1, 2] Moisture content — The amount of water in a material on a stated wet or dry mass basis. Excess moisture can cause processing defects. Names and abbreviations: feedstock moisture. [1, 2] High-density polyethylene (HDPE) — A polyethylene grade family used as a WPC matrix. Resin grade, melt flow and additives matter more than the acronym alone. Names and abbreviations: PE-HD. [1, 2] Polypropylene (PP) — A thermoplastic matrix used in natural-fibre composites. Processing conditions and compatibility with fibres must suit the selected grade. Names and abbreviations: polypropene. [1, 2] https://woodplasticcomposite.net/guides/wpc-glossary-terms-standards/#glossary-group-2 ## Polymers and interface chemistry Polyvinyl chloride (PVC) — A thermoplastic used in some composite profiles. WPC does not mean PVC-free; confirm the actual formulation rather than assuming resin identity. Names and abbreviations: vinyl polymer. [1, 2] Polyethylene (PE) — A family of thermoplastics including HDPE and LDPE. Different grades have different density, flow and mechanical behaviour. Names and abbreviations: polythene. [1, 2] Low-density polyethylene (LDPE) — A more highly branched polyethylene family. Its properties differ from HDPE; changing resin can alter composite stiffness and processing. Names and abbreviations: PE-LD. [1, 2] Polylactic acid (PLA) — A polyester often made from renewable feedstocks. Bio-based origin does not establish outdoor durability or degradation under ordinary garden conditions. Names and abbreviations: polylactide. [1, 2] Recycled HDPE (rHDPE) — HDPE recovered for reuse. Contamination, previous ageing and batch consistency must be controlled when producing repeatable WPC formulations. Names and abbreviations: reprocessed high-density polyethylene. [1, 2] Maleated polypropylene (MAPP) — A functionalised polypropylene used to improve fibre–matrix compatibility in suitable systems. Dosage and effectiveness depend on the formulation. Names and abbreviations: maleic-anhydride-grafted polypropylene. [1, 2] Maleated polyethylene (MAPE) — A functionalised polyethylene used as a compatibiliser in suitable PE-based composites. It is not automatically interchangeable with MAPP. Names and abbreviations: maleic-anhydride-grafted polyethylene. [1, 2] Coupling agent — An additive promoting interaction between dissimilar constituents. A compatibiliser has a related role, but the terms are not exact synonyms in every chemistry. Names and abbreviations: interface modifier. [1, 2] Lubricant — An additive reducing friction during processing. Excess or unsuitable lubricant can affect bonding, surface quality and mechanical properties. Names and abbreviations: processing lubricant. [1, 2] UV stabiliser — An additive intended to reduce light-driven deterioration. It does not make every colour or exposed wood component permanently unchanged. Names and abbreviations: light stabiliser. [1, 2] https://woodplasticcomposite.net/guides/wpc-glossary-terms-standards/#glossary-group-3 ## Additives and primary processing Antioxidant — An additive limiting oxidative damage during processing or use. Its effectiveness depends on chemistry, concentration and exposure. Names and abbreviations: oxidation stabiliser. [1, 2] Pigment — A dispersed colouring material. Colour influences appearance and can affect solar heating; a dark surface is not necessarily cool underfoot. Names and abbreviations: colourant. [1, 2] Flame retardant — An ingredient intended to modify burning behaviour. Its presence does not establish a product fire classification without appropriate testing. Names and abbreviations: fire-retardant additive. [1, 2] Extrusion — Continuous shaping of a heated compound through a die. Cooling and calibration help establish the profile dimensions. Names and abbreviations: profile extrusion. [1] Co-extrusion — Simultaneous formation of multiple material streams into a layered product. A cap can differ chemically from the composite core. Names and abbreviations: multilayer extrusion. [1] Cap layer — An outer layer modifying surface behaviour. Coverage, thickness and adhesion matter; a cap does not make cut ends or joints automatically waterproof. Names and abbreviations: capping; protective shell. [1] Injection moulding — Shaping a molten compound by injecting it into a mould. Flow, fibre orientation and cooling influence the finished component. Names and abbreviations: injection molding. [1] Compression moulding — Shaping material under pressure in a mould, often with heat. It differs from continuous extrusion and can suit panels or formed parts. Names and abbreviations: compression molding. [1] Compounding — Mixing constituents to distribute filler and additives through a polymer. Dispersion must be balanced against heat exposure and fibre damage. Names and abbreviations: melt blending. [1] Drying — Reducing moisture before processing. The required target depends on feedstock, polymer and equipment; one universal drying schedule is inappropriate. Names and abbreviations: feedstock drying. [1] https://woodplasticcomposite.net/guides/wpc-glossary-terms-standards/#glossary-group-4 ## Finishing, printing and product types Extrusion die — The tool opening that shapes an extrudate. Die geometry must account for flow, swelling, cooling and dimensional tolerances. Names and abbreviations: profile die. [1] Calibration — Controlling an extruded profile's shape and dimensions while it cools. Poor control can produce distortion or inconsistent wall thickness. Names and abbreviations: profile sizing. [1] Embossing — Creating a pattern on a surface, often to imitate grain. Visual texture alone does not prove wet slip resistance. Names and abbreviations: surface texturing. [1] Sanding — Removing surface material to change finish or texture. Sanding a capped board can damage its protective layer; follow product instructions. Names and abbreviations: surface abrasion. [1] Fused filament fabrication (FFF) — Layer-by-layer printing with heated filament. Wood-filled feedstocks require suitable moisture control, nozzle selection and extrusion settings. Names and abbreviations: fused deposition modelling; FDM. [1] Melt flow rate (MFR) — Mass passing through a specified die over time at stated temperature and load. Values measured under different conditions are not directly comparable. Names and abbreviations: melt flow index; MFI. [9] Solid profile — A profile without intentional longitudinal hollow chambers. Solid geometry alone does not establish structural capacity or a permitted support span. Names and abbreviations: solid composite board. [1] Hollow profile — A profile with internal chambers. Wall thickness, rib arrangement, impact resistance and end detailing affect its suitability. Names and abbreviations: hollow-core board. [1] Composite decking — Boards intended as an outdoor walking surface over supports. Verify span, slip behaviour, fastening and exposure for the exact product. Names and abbreviations: WPC decking; composite deck boards. [1] Composite cladding — Profiles used as an exterior covering. Fire, wind, fixing and ventilation requirements belong to the complete façade system. Names and abbreviations: WPC cladding; façade profiles. [1] https://woodplasticcomposite.net/guides/wpc-glossary-terms-standards/#glossary-group-5 ## Applications and installation Composite fencing — Composite elements used in fences or screens. Posts, foundations and connections must resist the site's wind loads. Names and abbreviations: WPC fencing; privacy screen boards. [1] Joist — A member supporting decking boards. Some WPC joists require continuous support and must not be assumed to be spanning structural beams. Names and abbreviations: deck support member. [1] Fascia board — A finishing board covering deck edges or risers. Decorative fascia is not automatically suitable as a load-bearing tread or joist. Names and abbreviations: edge trim; finishing board. [1] Tongue and groove — A joint with a projecting tongue fitting a groove. A closed-looking joint is not proof of a watertight assembly. Names and abbreviations: T&G; interlocking profile. [1] Hidden fastener — A fixing system reducing visible screw heads. Clip spacing, movement allowance and compatibility must follow the board manufacturer's instructions. Names and abbreviations: concealed fixing; decking clip. [1] Expansion gap — A designed clearance for dimensional movement. Required gaps depend on board length, temperature, material and the installation system. Names and abbreviations: movement allowance. [1] Joist spacing — The distance between support centre lines. Approved values depend on board geometry, loads, temperature and application, including stairs. Names and abbreviations: support centres; centre-to-centre spacing. [1] Ventilation — Air exchange around an assembly to assist drying. Necessary clearances depend on the construction; an enclosed damp cavity can retain moisture. Names and abbreviations: under-deck airflow. [1] Drainage — Providing a route for water to leave an assembly. Board joints alone do not replace drainage design beneath a deck. Names and abbreviations: water management. [1] Maintenance — Cleaning and inspection needed to retain function and appearance. Low maintenance does not mean no cleaning or no inspection. Names and abbreviations: deck care; routine cleaning. [1] https://woodplasticcomposite.net/guides/wpc-glossary-terms-standards/#glossary-group-6 ## Mechanical properties and durability Tensile strength — Stress sustained during a defined pulling test. Specimen preparation, direction and conditioning affect results; it is not a deck span rating. Names and abbreviations: strength in tension. [7] Flexural strength — A strength measure obtained in bending under a stated method. Compare geometry and conditioning before comparing numerical values. Names and abbreviations: bending strength; MOR. [6] Elastic modulus — The relationship between stress and strain in a specified range. Stiffness differs from strength; tensile and flexural moduli are not interchangeable. Names and abbreviations: stiffness modulus; MOE. [6, 7] Creep — Progressive deformation under sustained load. Temperature, stress and time affect it, so short bending tests cannot establish long-term deflection alone. Names and abbreviations: time-dependent deformation. [1, 3] Impact strength — Resistance measured under a specified impact test. Notched and unnotched results, and different test methods, are not interchangeable. Names and abbreviations: impact resistance. [1, 3] Water absorption — Water taken up under specified exposure conditions. Duration, temperature and specimen geometry must accompany a reported percentage. Names and abbreviations: moisture uptake. [3, 8] Thickness swelling — Increase in thickness following moisture exposure. It differs from mass-based water absorption and should be reported separately. Names and abbreviations: moisture-induced swelling. [1, 3] Thermal expansion — Dimensional change as temperature changes. The relevant coefficient, board length and temperature range inform movement allowances. Names and abbreviations: temperature-driven movement. [1, 3] Weathering — Changes caused by sunlight, moisture and temperature exposure. Colour retention and retained mechanical performance are different outcomes. Names and abbreviations: outdoor ageing. [1, 3] Slip resistance — Resistance to slipping under specified test conditions. Wetness, contamination, footwear and surface wear matter; grooves alone are not proof. Names and abbreviations: slip performance. [14] https://woodplasticcomposite.net/guides/wpc-glossary-terms-standards/#glossary-group-7 ## Laboratory methods and service evidence Density — Mass divided by volume using a stated measurement basis. Profile geometry and internal voids complicate comparisons with material density. Names and abbreviations: mass per unit volume. [1, 3] Thermogravimetric analysis (TGA) — A method measuring mass changes during a controlled temperature programme. It helps study decomposition but does not directly determine service life. Names and abbreviations: thermal mass-loss analysis. [1, 3] Differential scanning calorimetry (DSC) — A method measuring heat-flow differences during heating or cooling. It can investigate polymer melting and crystallisation. Names and abbreviations: thermal analysis. [1, 3] Scanning electron microscopy (SEM) — Imaging that reveals fine surface or fracture features. Images can support interface analysis but do not alone quantify bond strength. Names and abbreviations: electron microscopy. [1, 3] Fourier-transform infrared spectroscopy (FTIR) — A technique probing molecular vibrations through infrared absorption. It helps identify chemical groups; interpretation requires suitable controls. Names and abbreviations: infrared spectroscopy. [1, 3] Service life — The period a product meets stated requirements in its actual exposure and maintenance conditions. It is not identical to a warranty period. Names and abbreviations: useful life. [1, 3] Warranty — A supplier's stated contractual remedy with conditions and exclusions. Its duration is not a measured physical lifespan. Names and abbreviations: commercial guarantee. [1, 3] Traceability — Connecting delivered products to manufacturing, raw-material and quality records. A supplier name alone is not complete batch evidence. Names and abbreviations: batch traceability. [1, 3] Recycled content — The proportion of recycled material on a declared basis. Distinguish whole-product percentages from percentages referring only to the polymer fraction. Names and abbreviations: recycled material share. [1, 3] Recyclability — The ability to collect and process material into a useful output. Actual acceptance, sorting and local facilities must also exist. Names and abbreviations: recycling potential. [1, 3] https://woodplasticcomposite.net/guides/wpc-glossary-terms-standards/#glossary-group-8 ## Circularity and technical documentation Bio-based — Made wholly or partly from biological feedstock. Bio-based content does not mean biodegradable, compostable or automatically lower impact. Names and abbreviations: biomass-derived. [1, 13] Biodegradability — Breakdown through biological activity under specified conditions. Results depend on environment and time; wood content does not make ordinary WPC compostable. Names and abbreviations: biological degradation. [1, 13] Life cycle assessment (LCA) — Assessment of environmental impacts across a defined system. Comparisons require compatible functions, boundaries, assumptions and service-life scenarios. Names and abbreviations: life-cycle analysis. [13] Environmental product declaration (EPD) — A structured declaration of environmental data based on defined rules. An EPD is not by itself an environmental superiority label. Names and abbreviations: environmental declaration. [12, 15] Carbon footprint — Greenhouse-gas emissions expressed as carbon-dioxide equivalents within a defined boundary. Transport distance alone does not establish the total product footprint. Names and abbreviations: greenhouse-gas footprint. [13] Batch — A traceable production quantity sharing defined manufacturing conditions. Batch identification helps connect deliveries, samples and quality records. Names and abbreviations: production lot. [1, 13] Test method — A defined way to measure a property. Naming a method does not provide a result or prove a product passed a requirement. Names and abbreviations: testing procedure. [4, 5] Product specification — A document defining required characteristics and intended scope. It should identify the product, applicable tests, acceptance criteria and installation conditions. Names and abbreviations: technical specification. [4] EN 15534 — A multi-part series for cellulose-based materials combined with thermoplastics. Select the relevant test or product part; the number alone is insufficient. Names and abbreviations: European WPC/NFC standards series. [4] ISO 16616 — A standard addressing test methods for exterior natural-fibre composite deck boards. A test report must identify the applicable edition and product. Names and abbreviations: NFC deck-board test methods. [5] https://woodplasticcomposite.net/guides/wpc-glossary-terms-standards/#glossary-group-9 ## Product standards and test standards EN 15534-4 — The decking product part of EN 15534. Its scope is not automatically interchangeable with the cladding or fencing parts. Names and abbreviations: decking profiles and tiles. [4] EN 15534-5 — The cladding product part of EN 15534. A decking result does not establish compliance for a façade application. Names and abbreviations: cladding profiles and tiles. [4] EN 15534-6 — The fencing product part of EN 15534. Product requirements do not replace site-specific design of posts and foundations. Names and abbreviations: fencing profiles and elements. [4] ISO 178 — A method for investigating flexural properties of plastics. Use the stated edition, specimen and conditions; a draft revision is not a published replacement. Names and abbreviations: plastics flexural testing. [6] ISO 527 — A series addressing tensile properties of plastics. Select the appropriate part and specimen conditions for the material being evaluated. Names and abbreviations: plastics tensile testing. [7] ISO 62 — A standard for determining water absorption under controlled conditions. It is not a blanket declaration that a finished assembly is waterproof. Names and abbreviations: plastics water absorption. [8] ISO 1133-1 — A standard covering melt mass-flow and volume-flow measurement. Temperature and applied load are essential parts of a reported result. Names and abbreviations: thermoplastic melt-flow testing. [9] EN 13501-1 — A classification standard using reaction-to-fire test data. Classification applies within its documented scope, not automatically to every assembly or profile. Names and abbreviations: reaction-to-fire classification. [10] ASTM D7032 — A performance-rating specification covering composite and plastic-lumber deck boards, stair treads, guards and handrails. It is not a European approval. Names and abbreviations: composite decking performance ratings. [11] EN 15804 — Core rules for construction-product environmental declarations. Meaningful comparisons require compatible rules, declared units, modules and scenarios. Names and abbreviations: construction-product EPD rules. [12] https://woodplasticcomposite.net/guides/wpc-glossary-terms-standards/#glossary-group-10 ## Green Plank products and documentation Explore Green Plank product ranges and request the current technical data for your selected profile. These are commercial manufacturer links, not independent evidence for the definitions. https://woodplasticcomposite.net/guides/wpc-glossary-terms-standards/#green-plank ## Key points ## Comparison ## Sources 1. USDA Forest Products Laboratory — Wood/Nonwood Thermoplastic Composites — https://research.fs.usda.gov/download/treesearch/42497.pdf 2. USDA Forest Products Laboratory — Raw materials for wood-polymer composites — https://research.fs.usda.gov/treesearch/36721 3. USDA Forest Products Laboratory — Fungal and moisture durability of WPC — https://research.fs.usda.gov/treesearch/68010 4. BSI — EN 15534 series: scope of parts 1, 4, 5 and 6 — https://landingpage.bsigroup.com/LandingPage/Series?UPI=BS+EN+15534 5. ISO 16616 — exterior NFC deck-board test methods — https://www.iso.org/standard/57285.html 6. ISO 178 — flexural properties of plastics — https://www.iso.org/standard/70513.html 7. ISO 527-1 — tensile properties of plastics — https://www.iso.org/standard/527-1 8. ISO 62 — water absorption of plastics — https://www.iso.org/standard/41672.html 9. ISO 1133-1 — melt mass-flow and volume-flow measurement — https://www.iso.org/standard/83905.html 10. BSI — EN 13501-1: reaction-to-fire classification — https://knowledge.bsigroup.com/products/fire-classification-of-construction-products-and-building-elements-classification-using-data-from-reaction-to-fire-tests 11. ASTM D7032 — performance ratings for deck boards, stair treads, guards and handrails — https://store.astm.org/d7032-21.html 12. EPD International — construction-product PCR and EN 15804 — https://www.environdec.com/pcr-library/pcr_6b99d07c-4b75-4763-4485-08dd775d2e49 13. ISO 14040 — life cycle assessment framework — https://www.iso.org/standard/37456.html 14. HSE — assessing slip resistance of flooring — https://www.hse.gov.uk/pubns/geis2.htm 15. EPD International — what environmental declarations communicate — https://www.environdec.com/news/comms-guidance-empco 16. Green Plank — Composite decking — https://greenplank.eu/products/composite-decking 17. Green Plank — Composite cladding — https://greenplank.eu/products/fluted-panels 18. Green Plank — Composite fencing — https://greenplank.eu/products/fencing 19. Green Plank — Fascia board — https://greenplank.eu/products/accessories 20. Green Plank — Product specification — https://greenplank.eu/inspiration/technical-data-downloads