ᐅ WPC vs. Stone – Impact on Heating?

Grym schrieb:
Ok, but how does it compare to natural stone/tile/etc.?

WPC is made from a wood fiber and plastic composite, right? I'm not entirely sure. Stone is a very good conductor and storage medium of heat—probably the best. Wood is not.

Therefore, stone should generally feel warmer than WPC.

I don’t think numbers will help you much here because a lot of it is subjective.

ypg schrieb:
I don't think numbers will help you much here, because a lot of it is subjective.

See my Google reference. They exposed 8 different materials to sunlight and measured the surface temperature...

We installed light gray WPC decking boards.
They do not retain heat and become very hot under direct sunlight.
Tiles and similar materials only retain heat longer, but even then, you can't walk on them barefoot at 30°C (86°F) in direct sun.
Therefore, it doesn't really matter — everything gets very hot.

ypg schrieb:
WPC is made of a wood fiber-plastic composite, right? I’m not sure.

WPC consists of wood fibers or wood flour mixed into plastic, basically serving as a filler. In plastics, you can also find materials reinforced with glass fibers (though not typically in construction or furniture). It’s basically similar to particleboard or MDF, but with a thermoplastic polymer (PP) instead of glue. The wood content varies significantly. In technical applications, it is usually no more than 20%, while in construction it is often around 50%. Asian WPC products almost always have a wood content over 50%, because that allows them to be classified as wood by definition. The combination of plastic and wood is actually excellent:
- resistant to weathering (microorganisms, animals, water, sun, etc.), except possibly fading
- no risk of splinters
- can closely resemble real wood in appearance
- easy to work with
- dimensionally stable
- lighter than wood
- essentially a recycled material, since it can incorporate wood waste

However, the downside is the coefficient of thermal expansion, which is similar to plastic and considerably higher than wood, metal, or even stone. This means you have to consider that decking boards will expand in size when exposed to sunlight.

ypg schrieb:
Stone is a very good heat conductor and heat storage material. At least the best. Wood is not.

Both at the same time is not really possible. If a material stores heat well, it usually doesn’t conduct heat well. Stone, wood, and plastic are all poor heat conductors. That is why they are also used for insulation (although better options exist). Metal, on the other hand, is a perfect heat conductor. Plastic is also not a particularly good heat storage material. Wood and stone, however, are much better in that regard.

As others have already pointed out, there is no general statement that applies. It depends on the surface but especially on the duration of exposure to radiation. In principle, I would always choose materials with low thermal conductivity. These materials not only absorb heat more slowly but also release it slower. A metal plate heated to 60°C (140°F) feels much hotter than a stone surface at the same temperature. However, if the surface is exposed to strong sunlight all day, all materials get very hot.
I would consider WPC and stone to be on a similar level. WPC heats up faster, but if it is so hot that you can no longer walk on it, stone slabs won’t be comfortable either.

Attention. WPC develops significant static electricity.
For bridges or piers, an aluminum profile is installed every four to five planks, which are connected under the structure and grounded or wetted. That works. Karsten