In general, when laying large areas outdoors. When the flooring is exposed to temperature fluctuations, e.g. due to strong sun which quickly breaks through and shines on the flooring. This particularly applies to any areas larger than 15 m2. For large areas indoors, expansion strips may also be required. Temperature fluctuations due to large windows or doors, where strong sunlight may affect the flooring, should be taken into account. More information is available in the Laying Instructions. Please seek advice from store personnel or contact our customer service.