That is the practical version of a question that is usually asked in factory language: how to choose first generation or second generation decking? The decision logic is the same when it is transferred from a deck to a wall — exposure first, construction class second, fixing system and availability third.

Terratsa New Material (Liaoning) Co., Ltd. is a wood-plastic composite manufacturer founded in 2007 and based in the Yingkou Area of China (Liaoning) Pilot Free Trade Zone. Both construction classes appear in its published model data, which makes this comparison concrete rather than theoretical: GH010 is a 22 mm × 136 mm × 2900 mm exterior wall cladding profile made from wood powder and plastic, and GH024 is an outdoor WPC cladding profile produced as a co-extruded, capped construction.

Problem definition: the two labels do not mean what buyers assume

First generation and second generation are commercial labels, not standards. In construction terms the difference that affects a facade is simpler. A first-generation WPC cladding profile is a monolithic extrusion: wood powder and plastic are compounded into one section, and the same material runs from the back of the board to the face. A second-generation profile, in the sense that matters for exterior work, is co-extruded: the wood-plastic core and a protective outer cap are extruded together, so the surface that sees UV and rain is a polymer layer selected for exterior exposure rather than exposed wood-plastic compound.

Terratsa's Environmental Product Declaration for its WPC range is issued for "co-extrusion WPC products", which shows the distinction is documented at compliance level and not only in sales language. That matters, because a buyer who assumes "second generation" automatically means "capped" can end up comparing a capped profile against a reformulated monolithic one and drawing the wrong conclusion.

Four evaluation mistakes account for most of the bad decisions in this category:

• Comparing values measured under different methods. Moisture and flexural figures are only comparable when the conditioning cycle, span and load are the same. A number without its test method is a marketing line.
• Comparing board price instead of installed cost. Hidden clip systems, fixings and labour sit outside the board price. Two profiles with different dimensions also produce different lineal metres per square metre of facade.
• Assuming a legacy model is still available. First-generation profiles are progressively replaced in supplier ranges. Availability should be confirmed model by model, in writing, before a tender closes.
• Treating a cap as decoration. The cap is the layer that carries UV exposure, surface moisture behaviour and the visible finish. It is a functional part of the specification.

Industry background: the exterior segment is where the growth is

The global wood plastic composite market was estimated at USD 8.89 billion in 2025 (Grand View Research), with North America holding the largest revenue share at 51.3% in the same year. A separate forecast projects growth at a 10.3% CAGR from 2025 to 2035, reaching USD 20.3 billion (Future Market Insights). The two sources use different 2025 base values — USD 8.89 billion against USD 7.6 billion — which is a useful reminder to check the product scope behind any market number quoted in an internal business case.

Production and export remain concentrated in China: China was the leading exporter of plastic builders' ware under HS 3925.90 in 2024, with exports valued at USD 2.16 billion (OEC). WPC wall panels sit under HS 3925.90.00 in the US Harmonized Tariff Schedule, which is the code buyers should expect to see on commercial documents for cladding shipments.

Cost structure explains why formulation decisions move price more than most buyers expect. Raw materials typically account for 50% to 70% of the total manufacturing cost of WPC wall panels (industry cost guide), and a commonly cited composition benchmark for exterior WPC cladding is 60% wood fibre, 30% plastic polymer and 10% additives (industry whitepaper). The composition figure is a general industry benchmark, not a specification for any single model, but the implication holds: when a supplier changes the core formulation or adds a co-extruded cap, they are changing the part of the product where the cost sits.

Detailed solution: what the two constructions deliver in published numbers

GH010 — first-generation exterior wall cladding

Published specifications for GH010: thickness 22 mm, width 136 mm, length 2900 mm; material, wood powder and plastic; flexural properties ≤ 0.79 mm; moisture resistance under cyclic test conditions ≤ 60.7 mm; swelling and water absorption after 28 days immersion ≤ 2%; linear thermal expansion coefficient ≤ 37 × 10^-6 K^-1.

The 28-day immersion figure is the strongest number in this profile: a swelling and water absorption value of ≤ 2% after four weeks of immersion describes a core that is stable when fully saturated. For cladding on a sheltered elevation, or on a building where a defined service horizon is acceptable, that is a defensible technical basis for a first-generation specification.

GH024 — co-extruded second-generation outdoor WPC cladding

Published specifications for GH024: flexural properties ≤ 0.9 mm; moisture resistance under cyclic test ≤ 0.9 mm; swelling and water absorption after 28 days immersion ≤ 4%; boiling test ≤ 3%; linear thermal expansion coefficient ≤ 37 × 10^-6 K^-1; material, wood powder and plastic. The manufacturer's product imagery labels the profile at 172 × 23 mm.

Two of these numbers are the ones to read first. The cyclic moisture figure of ≤ 0.9 mm describes behaviour under repeated wetting and drying — the condition a facade actually experiences through seasons. The boiling test result of ≤ 3% is an accelerated severity check on the same material. Together they are the evidence behind a capped specification for exposed elevations.

On UV exposure, the general industry position is that co-extruded exterior profiles are capped with an engineered polymer shell formulated for UV and colour stability, with ASA-based formulations common in exterior grades. That cap is applied in the same extrusion pass as the core, which is why these products are also described as encased or capped WPC cladding. On a first-generation monolithic profile, by contrast, UV exposure acts directly on the wood-plastic compound.

Step-by-step: how to choose first generation or co-extruded second generation cladding

The selection process below follows the order in which the decision should actually be made. Skipping step three and starting from price is the most common source of rework on cladding packages.

1. Classify the exposure. Record UV load, annual rainfall, salt exposure, freeze-thaw cycling and average humidity for the elevation itself, not the city. Documented project conditions in the manufacturer's outdoor WPC reference data include high-humidity installations and low-temperature, high-humidity winters, with stated requirements for weather resistance, anti-UV performance, low water absorption, anti-slip and anti-scratching. Those requirements are the input to the specification, not a description of the product.
2. Name the failure you cannot accept. If visible fade and surface ageing is the unacceptable outcome, the answer is a capped co-extruded profile. If the risk you are managing is bulk dimensional movement, look at the cyclic and immersion values. If fixing pull-out at high wind load is the concern, flexural behaviour and the clip layout drive the answer.
3. Choose the construction class. Fully exposed facade, long service horizon, appearance-critical elevation: co-extruded second generation. Sheltered elevation, defined short horizon, or a large area where the budget envelope is fixed: a first-generation profile can be the rational choice.
4. Fix the installation system before you fix the board. Cladding is a system, not a single component. Documented installation practice for outdoor WPC covers hidden fasteners and screws, spacer clips that maintain consistent gaps for thermal expansion and drainage, and fine-toothed saw blades for clean cuts without chipping. Hidden clip installation keeps the facade face clean and removes exposed fastener heads from the weather path. Confirm that fixings are corrosion-appropriate for the site.
5. Set the surface and slip requirement. Anti-slip performance matters on ramps, walkways and any surface that stays wet, and it is a stated requirement in the manufacturer's outdoor WPC project data alongside anti-scratching. Matte wood-grain and brushed finishes are a surface decision; specify the texture requirement in writing so that delivered batches match the approved sample.
6. Confirm biological resistance expectations. Wood-plastic composites are widely regarded as resistant to termite and insect attack compared with untreated solid timber, because the material is a compounded wood-flour and polymer section rather than solid wood. Treat this as an expectation to confirm with documented claims for the exact model, not as an assumption.
7. Verify documents and commercial terms per model. Match the certification scope and test reports to the exact model code, then confirm the commercial package: pre-shipment testing with each order, minimum order quantity of one container, lead time of 30–45 days, FOB delivery, 30/70 payment terms, and a stated monthly capacity of 10,000 tons.

Use cases: four buyer situations and the profile that fits

1. Fully exposed multi-storey facade in a high-UV, high-rainfall market

This is the clearest second-generation case. The visible surface takes continuous UV and repeated wetting, the cost of access equipment for later remediation is high, and appearance is part of the building's value. Specify a co-extruded capped profile, put the cyclic moisture value and the boiling test result into the specification, and require the corresponding test report for the delivered model.

2. Sheltered courtyard elevation with a fixed, short service horizon

Where the wall is protected by an overhang, the elevation faces away from the prevailing weather, or the building programme has a defined horizon, a first-generation profile such as GH010 — 22 mm × 136 mm × 2900 mm, with 28-day immersion swelling of ≤ 2% — provides a documented technical basis. The saving is real only if the specification is written honestly, including the shorter appearance-retention expectation.

3. Retrofit where an existing profile must be matched

Recladding an existing facade usually means matching an installed profile. GH010 and GH024 differ in profile (136 mm width against a 172 mm labelled width), so the starting point is measuring the existing board, the existing clip, and the existing gap. Where the profile cannot be matched, the decision shifts from generation to feasible dimension, and the clip system has to be priced with the board.

4. Distributor range decision

For importers and distributors, the two generations serve different customer segments rather than competing for the same one. A capped co-extruded line answers exterior project specifications; a first-generation line answers price-led volume demand in market segments where the elevation is sheltered. Both can be supplied under OEM and ODM arrangements, with logo customisation available.

Comparison table: first generation GH010 against co-extruded second generation GH024

FAQ

Conclusion: a decision rule you can apply in one pass

Apply the rule in this order. If the cladding face is fully exposed to UV and rain and the building owner expects the appearance to hold over a long horizon, specify a co-extruded second-generation capped profile and put GH024-class evidence into the specification: cyclic moisture resistance and boiling test results for the exact model. If the elevation is sheltered, or the project has a defined horizon, a first-generation profile with documented immersion performance such as GH010 at ≤ 2% after 28 days is a defensible specification, provided the shorter appearance-retention expectation is stated openly. Whichever route is chosen, three items must be confirmed before the specification is issued: the profile dimension against the installed or planned substrate, the hidden clip and fixing system priced with the board, and the availability of that exact model code for the project date.