Will WPC decking expand and contract ?
WPC decking will expand and contract, not as much as regular wood, but it still happens.
Composite decks are usually made from a mixture of wood powder, plastic particles and other additives. Due to the high plastic content (about 30%), they will respond to changes in temperature and have different coefficients of thermal expansion and contraction. When temperatures rise, composite decking expands, and when temperatures drop, they shrink. Although composite decks expand and contract relatively little, they may experience some degree of thermal expansion and contraction during extreme temperature changes or exposure to sunlight.
What affects the expansion and contraction of WPC decking?
1. Temperature changes: Thermal expansion and contraction of composite decks are mainly caused by temperature changes. The material expands when the temperature increases and contracts when the temperature decreases. If you live in a country or region with a large temperature difference between day and night, please be sure to pay attention to this.
2. Choice of deck color: The choice of different colors will also have different effects on the expansion rate of the deck. This involves a very basic physics knowledge. The darker the object, the more heat it absorbs. The same is true for outdoor decks. If you live in an area where the sun shines a lot, but you really like a dark deck, you have to consider it. For example, install some sunshade items on the deck, such as pergolas, parasols, etc. .
Of course, there are other ways to prevent thermal expansion and contraction, which we will answer in detail below.
3. Water accumulation: No matter what material it is, it will change if it is soaked in water for a long time, and the same is true for WPC decks.
Scientific installation is the most important method to slow down the expansion and contraction of WPC decking
Although expansion and contraction are inevitable, there are ways to reduce its deformation.
Installation is a crucial part of the entire WPC deck use process. It can be said that about 60% of the problems that occur in the later use of WPC decks are caused by irregular installation methods (such as deformation, warping, cracking, etc.).
Like common building facades in real life, they are composed of different materials, such as bricks, stone or metal sheets. These materials have different thermal expansion and contraction coefficients under temperature changes, so design and construction measures need to be taken to deal with this difference. For example, stresses and deformations in exterior wall materials caused by temperature changes can be reduced through the use of expansion joints, suitable connecting and fastening systems, and suitable thermal insulation materials.
The same is true for our WPC decks. During the installation process, gaps need to be left. These gaps are usually left when installing screws or clamps to allow a certain amount of movement space. Additionally, specially designed telescoping materials can be used to fill gaps to protect the deck and provide better weather resistance. If it is not standardized, it will cause damage to the deck itself:
1. Deformation and warping: Without enough space for expansion, composite decking may deform and warp when thermally expanded, resulting in uneven surfaces and structural problems.
2. Cracks: If the composite deck is restricted and cannot expand and contract freely when the temperature changes, it may cause cracks on the surface, affecting the appearance and service life.
As for how big a gap needs to be left, we can give a rough range:
| Outdoor Temperature | Gap Width |
| Below 4℃ | 6mm |
| Between 4℃-25℃ | 3mm |
| Above 26℃ | 1mm |
SENLAI’s WPC products have been proven to expand and contract less than other composite materials
Compared with other products, SENLAI has smaller fluctuations, mainly for two reasons:
1. SENLAI can customize the length and size of the deck according to your needs, whether it is 3 meters or 4.8 meters in length, it can be cut. This not only makes storage and installation more flexible and convenient, but also allows it to handle any climate with less fluctuation. On the premise of ensuring quality, reducing the length of a single deck can reduce the degree of deck changes.
2. SENLAI can adjust the formula ratio of raw materials according to the differences in climate in various countries and regions. When exposed to direct sunlight and extreme low temperatures, a larger plastic ratio will lead to greater expansion and contraction. Adjusting the recipe ratios of raw materials before starting can largely prevent this from happening. You can tell our staff the country and region you are in, and we will provide a customized solution after analyzing the local climate environment.
