Does Trex decking require gapping between boards?
Yes, in both directions. While Trex decking will not noticeably shrink or swell due to changes in moisture, changes in temperature will cause slight expansion/contraction. Therefore, gapping is required both side-to-side and at the end joints to allow for thermal expansion/contraction. Rules of Thumb: For end joints for 16′ boards and smaller, allow a minimum of 1/16″ gap for every 20°F of difference between installation temperature and the hottest temperature expected. For width-to-width gap required is 1/4″. For cold weather installations, 3/8″ is recommended.
