Do rubber tiles and rubber mats change dimensions with heat, moisture and ageing?
Yes, their dimensions can change slightly. WARCO rubber tiles and mats are made from polyurethane-bound rubber granules and respond most noticeably to temperature. When warm they expand slightly, and they contract again as they cool. This movement is reversible. The dimensional tolerances in the product data sheet apply to the measurement conditions stated there and do not set an upper limit for thermal expansion.
Moisture primarily changes weight, not dimensions. Water drains through the open pores or evaporates, although a small amount remains within the pore space. It fills existing voids, making a tile heavier without making it larger. The vulcanised rubber granules and polyurethane binder absorb little water themselves. The bonded structure may therefore swell slightly, and this subsides again as it dries.
A small part of the dimensional change remains. After manufacture, the binder continues to cure, causing the tiles to shrink slightly. This process tapers off during the first few weeks. Over the years, little further change occurs as the granules slowly lose oily constituents and the rubber phase continues to crosslink. The effect is less pronounced with an EPDM wear layer than with end-of-life tyre granules.
Across an installed surface, these slight changes accumulate over many tiles. They usually become visible as a slightly wider joint at the perimeter, rather than at every joint between tiles. During installation, all tiles should be at roughly the same temperature and should not have been heated by direct sunlight. The specified installation temperature appears in the installation guidelines.