Installation Guide

The extrusion process Fortress Deck employs utilizes incredibly high pressures but low rates, resulting in products that are
generally more dense than wood. The PVC component of the material make-up is susceptible to slightly greater expansion and
contraction than traditional wood. This is partially mitigated by the intersection of bamboo fibers and mineral particles present
throughout a product’s profile.
The total change in length will depend on the total change in temperature and the length of the profile. The total change in length
of a 20' profile over a temperature change of 50°F will be (on average) approximately ¼ˮ. Compared to wood,
Fortress PVC experience more expansion and contraction. Timber is typically more susceptible to irregular activity, such as
twisting, and larger deformation due to moisture absorption. Fortress Deck products have an absorption rate of less than 0.2 %
and the movement of PVC is more uniform. As a result, Fortress Deck profiles will remain more true to their form.
The directional movement of PVC is easily accounted for during installation. The anticipated change in length can be accommodated
for using expansion gaps at either end, or at both ends depending on the intended design, by employing the Hulk hidden fastener
system. To optimize the size of the expansion gaps, the maximum expected temperature range - in relation to the installed
ambient temperature - should be calculated and the corresponding change in length calculated.
In cooler climates Apex
TM
boards expand at approximately 9/32" per 10' of composite deck board. When leaving an expansion
gap for each board one should compare the current installation temperature (ambient) to what is a common maximum or minimum
temperature for that site. If you are installing at 06:00 in the morning in the middle of winter it will be close to the minimum
temperature the board will experience, as a result the board will be the ‘shortest’ it will ever be at installation. As the temperature
rises the board will expand. When its get to the peak temperature in the middle of summer the board will have moved to the
‘longest’ it will ever be. The difference between the longest and shortest positions of the board dictate the required size of the
expansion gap. But the starting position of the expansion gap will depend on the starting temperature or installation temperature.
Therefore, boards installed closer to the minimum site temperature will have to have a relatively larger starting expansion gap.
Boards installed closer to the maximum site temperature will have to have a relatively smaller starting expansion gap as the
boards will ‘shrink’ as the temperature decreases.
5. Expansion and contraction
20' composite deck board
20' Board
10' 10'
9/32" gap9/32" gap
Estimated expansion allowance between 2 fixed points in a cooler climate.
20' (with expansion of 9/32" per side)
6
Apex
TM
Deck Installation Guidelines