1. Planning

1.1 UPM ProFi’s online Deck Planner enables you to optimize the design of your deck, as well as create a list of all the materials needed. It will also show you where double support rails or joists are needed.

1.2 In addition to offering superior low maintenance properties compared to timber, composite decking has other different properties. The deck boards will expand and contract slightly along their length with changes in temperature (typically 6 mm for a 4 m board during a 40°Celsius temperature change). It is also normal that the relaxation of residual production stress may result in a small shortening of the deck boards in the first years after installation. Typical values are less than 0.5mm for Piazza Pro, approximately 1.5 mm for Piazza One & Deck 150 and up to 3 mm per m for Terra 127.

1.3 A detailed expansion table can be found in the Technical Data Sheets:

1.4 Plan your deck so as to minimize the number of board-end joints / expansion gaps e.g. by changing the board direction or using a framing board running at a 90° angle to the main area.

1.5 If uninsulated metal components (e.g. hand rails) in direct contact with the ground are installed adjacent to capped composite decking such as UPM ProFi Piazza Pro or One, it is possible in warm dry weather conditions that electrostatic charges generated while walking on the deck may result in shocks when touching these items. This can be avoided by ensuring that e.g. the hand rail is not in direct contact with the ground or using non-conductive materials such as plastic or wood, or by installing UPM ProFi Rubber Strip (please note that additional ventilation points might be needed, see chapter 2.3).

Gaps can be minimized by planning the deck board direction
Gap size is reduced when 90° framing boards are used
The decking boards should be installed without random staggering
Avoid random staggering by laying short and long deck boards alternately.