In Ontario both of these get sold as “composite cladding”, and on a showroom sample they look almost the same. They are not the same material. WPC is wood flour bonded with a plastic; ASA/PVC has no wood in it at all. On a deck that difference shows up slowly. On a wall it shows up faster and more visibly — as fading on the south elevation, and as dark growth on the shaded north side. Here is the honest comparison, and what to ask whoever is quoting you.
| ASA/PVC (CladdiWood) | WPC wood-plastic composite cladding | |
|---|---|---|
| What it is made of | Foam-core PVC with a co-extruded ASA cap. No wood flour, no wood fibre — nothing organic in the board. | Roughly 50–60% wood flour bonded with a plastic, usually polyethylene. Capped, partly capped or uncapped depending on the grade. |
| What holds the colour | The ASA cap. ASA is the polymer used for car body trim and mirror housings precisely because it holds colour under UV. | The cap, where there is one. Uncapped WPC weathers fastest; PE caps are less UV-stable than ASA, and the wood underneath greys as it is exposed. |
| What the warranty covers | 15 years including colour fading — not only cracking or structural failure. Fade performance is stated as Delta E under 5. | Varies widely. Many WPC warranties cover structural failure but exclude or limit fading and staining. Read the exclusions, not the headline number. |
| Water, rot and mould | Nothing inside the board absorbs water, so there is nothing for mould to feed on and nothing to swell. | Wood flour takes on moisture, particularly through cut ends and any breach in the cap. Surface mould on shaded and north-facing walls is a documented issue for the material class. |
| Movement through an Ontario year | Thermally stable: a 12 ft board moves roughly 3 mm across a 40°C swing. That is why mitres and tight joints hold, and why siding gets no butt joints. | More movement, and it varies with moisture content as well as temperature. Installation guides generally call for visible expansion gaps. |
| Weight on the wall | Foam-core PVC is the lighter of the two — one person can hold a full-length board against a wall while the first screws go in. | Heavier for the same coverage, because wood flour is denser than a foam core. On a two-storey elevation that becomes a labour cost. |
| How it goes up | Regular flat-head screws, no pre-drilling. Each board hides the screw line of the one before it, so no fastener shows on a finished wall. | Depends on the system — many use clips or a starter track, and cut ends often need sealing to keep water out of the core. |
| Where it sits on price | The expensive end of the category, not the cheap one. Same material class as TimberTech Advanced PVC, which runs about double a Trex-type composite. | Spans the widest range of anything sold as composite — from entry-level uncapped board to capped premium lines. |
| Seeing it before you buy | Six colours held in stock in Markham, plus completed installations across the GTA you can go and look at on a real house. | Usually ordered in. Colour is often chosen from a swatch or a photo rather than a finished wall. |
“Composite” is used as a catch-all for both, which is where most of the confusion starts. WPC — wood-plastic composite — is wood flour blended with a plastic. ASA/PVC is a solid polymer with a UV-stable cap and no wood content. Both get called composite cladding at the counter, so the useful question is not “is it composite” but “does it have wood in it, and what is the cap made of”.
No, and the difference you will actually notice is thermal stability. Vinyl siding is designed to move: it hangs loose on its nails and needs room to slide, which is why the joints are lapped and why long runs can look wavy on a hot day. CladdiWood is foam-core PVC with a co-extruded ASA cap and moves about 3 mm over 12 ft across a 40°C swing, so it can be screwed tight, mitred at corners, and run without butt joints.
That is the wall the cap layer exists for. ASA is the polymer chosen for exterior automotive parts because it keeps its colour under UV, and it is co-extruded onto the outside of every board. Our warranty covers colour fading for 15 years at Delta E under 5, which is a number you can hold a supplier to — unlike “fade resistant”, which is not a specification.
Mould needs something organic to feed on. There is no wood in an ASA/PVC board, so what lands on a shaded wall is ordinary surface dirt and it washes off. WPC is a different situation: the wood flour is the food source, and moisture reaching it through a cut end or a scratch in the cap is what makes north elevations and shaded returns the first place WPC cladding goes dark.
A 12 ft board moves about 3 mm across a 40°C swing. Practically, that means siding gets no butt joints — boards run vertically and each one runs the full height, because a wall is almost never taller than 12 ft. If someone is quoting you a wall with visible butt joints in the field, ask why.
Vertical, as the default. A single board covers the full height of almost any wall, which removes the joints entirely, sheds water down the grain, and gives the elevation a cleaner line. Horizontal is possible but it reintroduces the joints, so it is a design decision with a maintenance consequence attached.
Our published rating is flame-retardant B1. A rating on its own is close to meaningless, though, because it only exists relative to the standard it was tested against — so ask us which standard and for the report, and ask the same of anyone else quoting you. Our performance sheet is on the resources page. Untreated WPC contains a combustible wood fraction, which is why fire performance for that class varies so much between products.
You can, but you would be giving up the thing you paid for. The colour is in the cap and it is warranted for 15 years; paint on top of it is a coating that will need redoing on a normal paint cycle. If you think the colour might change, the better move is to look at a finished wall in that colour before you order — we have installations across the GTA.
It is built for freeze-thaw: nothing in the board absorbs water, so there is no moisture inside to freeze, expand and open up microcracks. That cycle — water in, ice, split — is what ages wood and what stresses any material carrying a wood fraction. Snow load and ice on the wall are not an issue for a screwed-tight board.
Because it is a different material class, not a marked-up version of the same thing. Foam-core PVC sits at the expensive end of everything sold as composite — the same class as TimberTech Advanced PVC, which typically runs about double a Trex-type composite. If a quote is materially cheaper, the honest comparison is not price per square foot but what the warranty covers and what the cap is made of.
Both. We supply the material and we can put you with installers who have done a lot of these, so you are not left holding boards and looking for a crew. Material and labour are always quoted separately, and we do not take on structural work — framing, or building the structure of a canopy or pergola.
Yes, and for a wall we would rather you did. Colour reads differently on a 4-inch swatch than on a two-storey elevation, so the more useful step is usually the completed-projects page, where you can see each colour on a finished house and, if it is nearby, go and stand in front of it.
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YJJNANO Materials Canada Inc.