WHAT NOT TO DO when installing a composite deck Working with wood plastic composites (WPCs), especially the solid type like eco-Profil, is as easy as working with softwood timber. One should never assume that the general rules for working with natural materials do not apply for wood plastic composites. The main topics that have given rise to subsequent problems (and this holds for ALL WPC boards) are: - foresee end-to-end gaps that allow for thermal expansion;
- design and build your deck in such a way that sufficient ventilation/aeration allows the space beneath the deck to dry out as thoroughly as the deck surface:
- always stick to the support beam or joist spacing that is prescribed by the vendor.
END-TO-END GAPSWPC products tend to show some longitudinal expansion when heated. On sunny days, the sun can easily heat a deck to up 60°C. To compensate for the effects of thermal contraction and expansion, the following installation standards should be maintained: | End-to-end gap (mm) between boards for an expected surface temperature increase to 60°C | Board temperature during installation (°C) | Board length | | 2,4 m | 3 m
| 3,6 m | 4,2 m
| 4,8 m | | 10 | 4 | 5 | 6 | 7 | 8 | | 15 | 4 | 5 | 6 | 7 | 8 | | 20 | 3 | 4 | 5 | 6 | 6 | | 25 | 3 | 4 | 5 | 6 | 6 | | 30 | 3 | 4 | 4 | 5 | 5 | | 35 | 3 | 4 | 4 | 5 | 5 | | The decking must span at least three joists. |
Gap to be kept between the first board and an obstacle (e.g. a wall): keep 1 cm. Also, all board ends need to be supported and be fixedonto the supports on both sides! VENTILATEJust as with natural wood, a long term difference in humidity between the top and the bottom of the deck board can eventually lead to distortion of the board. Therefore, the following needs to be foreseen: - sufficient space between the supporting surface and the deck bottom, so as not to obstruct the natural flow of air below the deck;
- the sides of the deck need to be free to allow the natural air flow to aerate the space beneath the deck and fully dry out the supporting surface.
Flat areas where standing water may gather should be addressed by grading or improved drainage.
JOIST SPACING:Supports clearance: Max. 37 cm (14”) centre distance for residential use Max. 30 cm (12”) centre distance for commercial use
When the decking is to be laid diagonally, reduce the on-center joist spacing by 10 cm (4”). When installing heavy loads on top of your decking project, such as an above ground pool or hot tub, it is important to follow the requirements of the manufacturer as they always have specific framing and support requirements for their warranty purposes.
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