Volume: 58 | Issue: 1 | Download
What causes planar instability? Planar instability, that which prevents a modular flooring material, hard or soft surface from lying flat, is caused by internal forces generated by materials or layers in the flooring material, that exert forces or stress across or within the material, which create lifting or curling edges. This can occur on all four sides or two sides and is often in the "machine" direction or length, of the material. If, for example, a product is quarter turned the lifted edges will alternate — North South to East West and vice versa with every other tile. Planar stability is influenced by the forces within the flooring material and by changes in heat or humidity. There are tests to detect or prove the condition exists such as the cycled humidity test for carpet tile.