Premium Composite Decking: thick ASA Capped, Reinforced PVC Core, 30+ Year Weathering

Premium composite decking is the top band of the WPC range: a board capped on all four faces with ASA, a core that carries the load, and third-party test reports behind every number quoted below. We extrude it on our own lines in Foshan, Guangdong, and we publish the measurements because most of what is sold as premium is sold on adjectives. Where a test result answers a problem buyers actually have — fading, swelling, frost damage, boards working loose at the fixings — the number appears with the standard it was measured against, so you can check the method instead of trusting the claim.

What separates a premium board from an ordinary capped board

Almost every outdoor board sold today calls itself capped. The word covers boards with a thin film on the top face and boards wrapped on all four sides in a different polymer entirely. Five questions separate them, and a supplier who can answer all five in writing is usually selling the second kind.

What to ask	What a premium answer looks like
Is the cap on all four faces?	Four-sided cap; an exposed core edge is where moisture starts
What is the cap made of?	ASA or an equivalent UV-stable polymer, not a thin PE film
Does the colour run through the cap?	Pigment in the cap layer, not a printed or coated surface
How much does the board move?	A stated thermal expansion figure, and a system that allows it
What testing exists?	A third-party report with a standard number, not a claim

Specifications: four profiles, one system

All four profiles share the same cap and the same clip system, so you can mix widths on one job without changing the substructure. Area per board is nominal board face — length × width — and the clip gap between boards reduces the installed figure slightly, which is worth allowing for before you price a deck.

Picture	Profile	Board size	Length	Weight
	Standard-Solid	140 × 25 mm	2.9 m, or to order	3.1kg/m
	Standard-Hollow	140 × 25mm	2.9 m, or to order	2.8kg/m
	Standard-Solid	140 × 23mm	2.9 m, or to order	2.9kg/m
	Tight butt-Hollow	160 × 20mm	2.9 m, or to order	2.3kg/m

Regular composite decking usually requires 300-400 mm joist spacing, while this premium composite decking series can exceed 500 mm thanks to its higher strength, helping projects cut costs and lower overall budgets. And extra -long specifications and sizes are available upon customization.

Why a thick 360° ASA cap is what you are actually paying for

ASA — acrylonitrile styrene acrylate — is used where colour has to survive UV, which is why it turns up on automotive trim and outdoor cladding rather than on indoor furniture. On a deck it does one job: it holds the pigment in the outer layer instead of letting the sun work through it. Unlike other products that have an ASA cap of only 0.03 -0.04 mm, it is 0.08-0.10 mm. This makes its superior weather resistance self-evident and positions this premium composite decking series a standout performer on the market.

• Colour retention. The pigment sits in the capped layer, so a fade in year eight is a fade of the cap, not a repaint of the whole board. Designing surface layers to remain stable under prolonged high-UV radiation.
• Stain and scratch resistance. The surface closes the wood fibre off, so oil, wine and grill grease sit on top and wipe off.
• Low thermal expansion. The board moves less than an uncapped PE composite, which is what lets long runs work without an oversized gap.
• Wood grain that is extruded, not printed. The texture comes out of the die, so brushing it back does not reveal a smooth surface underneath.

Under the cap sits a reinforced PVC core. It is the part that carries the load and the part that keeps the board from absorbing water — the cap protects the colour, the core protects the section. With the cap intact, the service life we quote is 30+ years, and that figure assumes a ventilated substructure.

What actually fails outdoors, and the number we measured for each

Composite decking fails in a short list of predictable ways, and each one has a test that puts a figure on it. The table below is that list: what goes wrong, the test we ran against it, the standard the test follows, and the result from the report. No row is a promise — every row is a measurement you can ask to see.

What goes wrong	Test we ran	Standard	Measured
Boards take on water and swell at the cut edge	Water absorption and thickness swell, 24 h immersion at 23 °C	ASTM D7031-11(2019) §5.19 / ASTM D1037-12 §23 Method B	1.12 % absorption, 0.70 % swell
A northern winter cracks the section	Three freeze-thaw cycles (−29 °C), then flexural testing	ASTM D7032-21 §4.7 / ASTM D6109-24 Method A	MOR 54.4 MPa, MOE 4,560 MPa; −4.9 % and −3.0 % against control
Boards lift at the fixings under wind load and foot traffic	Fastener holding	ASTM D7032-21 §5.5 / ASTM D1761-20(2025)	2,380 N
Long runs buckle when summer heat arrives	Coefficient of linear thermal expansion	ASTM D696-24	3.195 × 10⁻⁵ /°C
Wet decking becomes a liability at the pool edge	Slip resistance, dry and wet, parallel and perpendicular to grain	ASTM D7032-21 §5.6 / ASTM D2394-17(2022) §33–37	Static 0.74–0.89, kinetic 0.72–0.90 — every reading above 0.6
Furniture, grit and heels grind the surface away	Abrasion, CS-17 wheel, 1,000 g load, 1,000 cycles	ASTM D7031-11(2019) §5.17 / ASTM D4060-25	110.6 mg loss
Dropped tools, hail, a shifting planter	Impact, 4.54 kg dart	ASTM D7031-11(2019) §5.12 / ASTM D4495-21	67 J mean failure energy
Planters and heavy furniture leave a dent that stays	Creep-recovery	ASTM D7032-21 §5.4	90 % recovery after load removal

Two rows need translating. Water absorption of 1.12 % is the reason a cut end does not swell open after a wet winter, and 0.70 % thickness swell is the number to compare against the uncapped boards that visibly cup at the board edge. On slip, specifiers commonly set 0.6 as the floor for a wet walking surface; the lowest wet reading on this board is 0.74 static and 0.76 kinetic, taken parallel to the grain — the direction a foot actually slides.

Board length	Movement over a 40 °C swing
2.9 m	3.7 mm
3.6 m	4.6 mm
4.0 m	5.1 mm
5.8 m	7.4 mm

That table is the thermal expansion coefficient turned into millimetres at your board length. It is the reason a 5.8 m run needs an expansion gap at each end rather than a hard-fixed butt joint — and the reason an installer who brings a PVC habit to a WPC deck is the most common cause of a board lifting in its second summer.

The step-by-step sequence matters here more than on a timber deck: the gap has to be designed at set-out, not discovered on the last board. The full run — joist spacing, where the gap goes, how the trim covers it — is set out stage by stage in the installation guide.

Colour: the number we publish, and the number we do not

Accelerated weathering is where most suppliers quote a single figure and stop. Ours changes at 4,000 hours, so it is worth showing you exactly where it changes and where we stop claiming.

Accelerated weathering	Mean ΔE*	What it means
1,500 h	0.64	Not visible
2,000 h	0.64	Not visible
2,500 h	0.70	Not visible
3,000 h	0.96	Still under 1 — not visible on a textured surface
3,500 h	1.87	Visible on close inspection
4,000 h	4.58	Visible at arm’s length; lightness L* rises 33.0 → 37.7

So we claim colour fastness to 3,000 hours, average ΔE* 0.96, and we do not claim the board is unchanged at 4,000. If you are comparing suppliers on hours, ask which colour and which ΔE — the same board passes or fails depending on the tone, and a number without a tone behind it is a number without a test behind it.

Scope, stated plainly: weathering, freeze-thaw, impact, slip, abrasion and moisture data were produced on the hollow profile at 140 × 25 mm; the compliance reports below were issued on the solid profile BY-N113Y16. Reports for any production profile we quote are available on request.

Eight colours, one grain family

All eight tones come off the same cap and the same extrusion die, so the brushed grain runs identically across the range — the only variable between them is pigment. That matters more than it sounds: a board whose grain is printed will show a different texture in every colour, and a replacement board ordered two seasons later will not match the first. See standard ASA capped line

Colour	Tone	Grain	Where it works
Golden Teak	Warm mid-brown, the lightest of the browns	Brushed linear	Decks that sit in full sun; the tone that reads closest to timber
Rosewood	Red-brown, high saturation	Brushed linear	Traditional and craftsman houses; warm-toned render
Walnut Brown	Deep chocolate brown	Brushed linear	Most forgiving on dirt and leaf tannin
Coffee Brown	Dark brown with a grey cast	Brushed linear	Contemporary facades, dark window frames
Sandstone	Cream to ivory	Brushed linear	Pool surrounds — reads cool underfoot and hides salt bloom
Silver Grey	Light cool grey	Brushed linear	Coastal and modern builds; the fastest-moving tone in the grey family
Slate Grey	Mid grey with a blue cast	Brushed linear	Rooftop terraces, commercial walkways
Charcoal	Near-black graphite	Brushed linear	High-contrast framing against light cladding

Colour performance is where the range is not uniform, and it is worth being straight about it. Our accelerated weathering data — mean ΔE* 0.96 at 3,000 hours — was produced on a brown/beige tone. Lightness drift is what shows first on a dark board, so if you are specifying Charcoal or Slate Grey for a high-UV project, ask us for the weathering report on that tone before you commit. We would rather send you an extra PDF than have a deck argued about in year six.

Screens lie about colour. Every tone is despatched as a physical sample before an order — tell us which two or three you are choosing between and we send those, not the whole fan.

The reports behind these numbers

Five reports sit behind this page, all issued in 2026 by SGS. Each carries a report number that can be checked against SGS’s own records, and the full PDFs go out with any quote or sample.

Report number	Issued	What it covers	Pages
GZIN2604000591CM01-1	25 May 2026	Freeze-thaw, impact, slip resistance, abrasion, water absorption, accelerated weathering	7
GZIN2604000591CM02	25 May 2026	Flexural, creep-recovery, fastener holding, thermal expansion	6
SHAIN26007224811	23 Apr 2026	Formaldehyde emission — ASTM D6007-22, 1 m³ chamber, CARB ATCM Phase 1 / TSCA Title VI	4
SHAIN26007224807	23 Apr 2026	EU RoHS 2015/863 — Pb, Hg, Cd, Cr(VI), PBB, PBDE, DEHP, BBP, DBP, DIBP	8
SHAIN26007224809	23 Apr 2026	REACH SVHC screening — 253 substances	15

For importers: the three files your customer will ask for

Substance / regulation	Substance / regulation Requirement	Result
Formaldehyde emission (CARB ATCM Phase 1 / TSCA Title VI)	Limit 0.08 ppm	Not detected — below the 0.01 ppm detection limit
EU RoHS 2015/863 — ten restricted substances	100–1,000 mg/kg per substance	Not detected — all ten, detection limit 2–5 mg/kg
REACH SVHC candidate list — 253 substances	None above 0.1 % w/w	Pass — none above 0.1 % w/w

A missing file is a container sitting at a port, or a retailer refusing to onboard a product line. All three are available as PDFs the same day, and the specimen declaration — solid profile, board code BY-N113Y16 — matches the compliance reports above so your importer is not reconciling two different sample descriptions. Request the test pack and it comes back with the report numbers, not a summary: ask for the test pack.

Colours, samples and what a screen cannot tell you

The range is matched to your project from our current colour line, and every enquiry gets a physical sample before an order — colour on a screen is not a colour, and every dispute I have seen in fifteen years started with a screen. Send the tone you are working to and we will send the board to hold against the deck it has to match.

Buying premium composite decking direct from the manufacturer

We are a WPC manufacturer, not a distributor — 47 extrusion lines, 5M+ m² a year, 30+ export markets, and fifteen years on the production side. That changes three things for a buyer: the price is FOB rather than landed, the spec is adjustable before the die runs, and the answer to a technical question comes from the line.

• Minimum order: 300 m² per board profile.
• Lead time: 25–30 days production before freight.
• Samples: A physical sample goes out before any order — send the tone you need to match.
• Mixed containers: Ask before you book — profiles and colours can usually be combined within one container.

Full terms, packing details and FOB pricing are on the trade terms page; if you would rather just send a drawing and a quantity, use the quote form and you will have a price within one business day.

What the board costs, and what a deck costs

A premium board runs $35–$42 per board depending on profile and finish, which works out to roughly $7.0–$9.30 per square foot — the spread is almost entirely board length, not quality. For the per-board arithmetic see the cost per square foot breakdown; for installed cost, substructure and what a whole deck comes to, start with composite decking cost.

FAQ

Send the quantity, the profile and the destination port, and you get FOB, lead time and packing back within one business day.