As temperatures fluctuate, composite deck boards will naturally experience thermal expansion and contraction. That’s why the board ends should never be installed tight against one another. There should always be a slight gap. How much of a gap? That will depend upon air temperature at the time of installation (Read this to learn more).
For areas that are subject to significant temperature swings, we recommend installing your deck boards using surface fasteners. First, ensure that the deck boards are aligned properly. Then, install a fastener in the middle of each board length to prevent shifting during thermal expansion and contraction.