PVC decking is a deck board made entirely of polyvinyl chloride, with no wood in it at all. It's the same plastic as PVC pipe and window profiles, both of which the Vinyl Council of Australia lists among PVC building products. Composite mixes plastic with wood fibre instead. PVC is pitched as the board for places where water, weight or fire make composite a compromise, and that's how I'd think about it.
What is PVC decking made of?
A 2009 US trade report described the PVC boards from two leading composite makers as a foam core surrounded by a rigid cap, which the trade calls cellular PVC2. The cap is co-extruded over the core, and one of those makers' product directors said it adds back some of the stiffness the foam lacks. One range sold in Australia describes its core as a foamed mineral-polymer mix under a double-layer polymer cap1. Another is sold as capped PVC decking, with the cap on all four sides4.
If a board is sold as solid PVC rather than foamed, I'd ask for its own install guide and check the spans, because the figures in this guide come from foamed boards.
Why it is lighter
The foam core keeps the weight down. The product director quoted in that 2009 report said cellular PVC boards can be as much as 40 per cent lighter than wood composites2. The Australian install guide for one PVC range says its boards are lighter than typical wood-plastic composite and easier to handle. On a timber-framed backyard deck that's a convenience. On an apartment balcony, a rooftop or a deck over a garage, I'd give the weight real attention, because the dead load of the decking goes into the engineer's numbers.
The flip side is stiffness. The same product director put a foamed PVC board's rigidity at around half that of a wood composite, with the cap adding some back2. In one current PVC install guide, the residential spans come out around 400 to 450 mm1. If someone tells you the light board means you can thin out the frame, they have it backwards.
Does PVC decking expand and contract?
Yes, and plain PVC moves more than composite in one maker's figures. That maker's install guide gives its plain PVC boards a coefficient of up to 0.07 mm per metre for each degree of warming, and its table lists the maker's polyethylene-based ranges at 0.040 to 0.0451. Its glass-fibre-reinforced PVC is listed lower again, at 0.0351, so it's worth asking which kind you're buying. A composite maker puts its own boards' growth at about 1.1 mm per metre between 15°C and a hot day7.
That guide's worked example is worth having in your head before you lay a board. A five-metre plain PVC board laid on a 22°C day and later sitting at 58°C needs about 12.6 mm of end gap in total1. Boards in direct sun are often 25 to 30°C hotter than the air, the guide says, so a 30°C day can put a board in the high 50s1. A Whirlpool member made the same point about composite in March 2023, warning a first-time builder that an eight-metre run could change length by up to 20 mm with temperature12.
The guide's steps are simple but easy to skip:
- Let the boards acclimatise on site before you install them1.
- Use breaker boards between boards laid end to end and a border around the edge, so each section's boards can be cut to the same length.
- Work out the gap from the board length and the temperature change, and adjust it if the temperature shifts during the job.
- Put doubled joists under any butt join so both board ends are supported.
- Choose a lighter colour where the temperature range is high, because the guide says it reduces the gap you need.
The guide on composite decking expansion gaps goes deeper into gap tables, and the same method works for PVC with the PVC guide's own coefficient.
Does PVC decking get hot?
Yes, especially in dark colours. One PVC maker says its boards are cooler to the touch than many other deck boards, and in the same footnote says all decking gets hot in the sun and darker colours feel hotter3. An Australian composite maker allows PVC slightly better heat dissipation than capped composite6. My reading is that a light-coloured PVC board is among the cooler synthetic choices and a dark one isn't. I'd say colour and shade decide most of it on any plastic deck, so read does composite decking get hot before picking a colour.
Water, stains and mould
This is where PVC is clearly better. With no wood in the board there's no organic material for mould to grow on, and the makers sell PVC as stain and mould resistant. One PVC range sold here is marketed for waterside use and tested in fresh, salt and chlorinated water4. The same maker says its boards won't swell when submerged, even after cutting. Composite isn't immune to water. A reviewer in far north Queensland wrote on Ekodeck's ProductReview listing in February 2026 that the boards swelled and split in the wet season. Ekodeck replied that the photo appeared to show another brand's composite board9. In one Whirlpool thread, though, the fear ran ahead of the evidence. A member who started it in November 2023 was looking at a board described as "almost PVC" because they'd been told composite swells, and the owners who replied hadn't noticed any10.
The Vinyl Council of Australia, an industry body, describes the non-slip surface of PVC decking and says outdoor PVC products withstand weather and abrasion5. Take an industry body's word for what it is, but the water point stands.
Can you paint PVC decking?
I'd leave it unpainted. PVC decking is sold as a board that doesn't need staining, sanding or painting, and the PVC install guide cited here doesn't give a method for coating the boards1. If a PVC deck has faded, start with a clean using the maker's method. Anyone still set on a coating should get the maker's answer in writing first. I'd want the warranty position clear before anything goes on. The guide on painting composite decking has a section on PVC as well.
How to install PVC decking
I'd follow the same sequence as for composite, with the expansion rules above added. Frame at the centres in the guide, use the clips or screws the maker lists, fix with two fasteners at every joist, and double the joists under any butt join1. Pre-drill if you're screwing in cold weather, because the guide asks for it below 5°C1. Cutting exposes the foamed core. The guide says to plan the layout to keep those edges out of sight. The overview in how to install composite decking runs through the order of work and the clips.
Where PVC makes sense
In my view it makes most sense around pools, for the water and salt, and on balconies and rooftops, for the weight. It also makes sense in bushfire zones. One US maker said in 2009 that its PVC boards are self-extinguishing and that two of its products were certified for California's wildfire zones2, and at least one PVC range sold in Australia is rated BAL 294. A Whirlpool member building a pool deck on a bushfire-prone block in far north Queensland in May 2023 needed exactly that combination, though they were shopping among composites for it11. The composite decking fire rating and BAL guide covers what to have ready for a certifier. For an ordinary backyard deck in part shade, I think PVC is paying for protection you don't need.
Before you order
Get the install guide for the exact board and read the expansion table before anything else, including whether the board is plain or reinforced PVC. If you need a bushfire rating, I'd ask what frame the board was tested on. One composite maker's BAL rating was achieved on aluminium joists8, so check with your certifier that the rating covers the frame you plan to build. Then put a sample in the sun at the site and touch it in the afternoon. If PVC still looks right, compare it with capped composite on your own deck size with the cost per m² calculator, and read PVC vs composite decking for the side-by-side.