The 9 golden rules of a professional composite decking installation

Composite materials behave differently than wood. In order to ensure a fast and professional installation of the deck while satisfying your customers and ensuring a long-lasting performance of your terrace, follow our 9 golden rules :

1. Be sure to read the full UPM ProFi installation instructions before starting to build the deck. These are included in every UPM ProFi Clip box and the latest version should be downloaded from this web site prior to any installation..

2. Unlike other composite deckings, UPM ProFi Deck may be built with a zero degree incline. However, to prevent the growth of mildew on the surface, air should be able to flow both above and below the deck.

3. UPM ProFi Support Rails can only be used when laid directly on a hard flat surface (eg. concrete): for raised decks, UPM ProFi Large Aluminium Support Rails or timber joists should be used. UPM ProFi Deck should not be installed on open joists on first floor or higher levels.

4. The support rails/joists should be fixed to the ground or constructed to form an inter-locking grid. This prevents thermal expansion of the deck boards distorting the design of the deck.

5. The maximum spacing between support rails / timber joists is 40cm from centre to centre. 30 cm spacing should be used when the deck boards are laid diagonally, or the deck is being used in extreme conditions: e.g. hot climate or a commercial application with high traffic. Please check the installation instructions for the correct spacing of joists for your chosen decking product.

6. It is recommended to open the pack, and lay the deck boards out to equalize the temperature before cutting to the desired length.

7. Thermal expansion gaps must be left at both ends of decking board. 6mm for 4m length will be enough for a 20 degree centigrade increase in the board temperature. The design of the deck will be enhanced if the board end gaps are in line or symmetrical.

8. The boards should be screwed to each support rail / joist with UPM ProFi Clips or Alu Rail. At one place only, directly screw the deck board to the support rail / joist. The screw should be through the bottom tongue in the middle of each board (one side only). This ensures that the boards stay fixed in place, whilst allowing for thermal expansion and contraction.

9. When two decking boards are placed end to end, double support rails and separate clips used for each board end.


To download our latest installation instructions, click here.

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