Decking

Wall cladding

Preparing the project

O.K., you’ve decided to build a WPC deck. Good! It will be an eco-Profil deck. Even better!

Before starting any practical preparations, plan the project !

Although this sounds obvious, too many decking construction projects eventually show poor results because of poor preparation.

For a privately owned terrace, some of the questions that need to be asked during the project’s initial phase are:

What do we want to use our deck for? Which size should it have? Will it just serve to sit some decking chairs and a small table or do we expect to entertain larger groups of people? How many people will it cater for?

Where will the water drainage go? Where do we want the slope to head towards?

Will we be using electrical appliances later on? Do we incorporate sockets?

How will we guarantee sufficient aeration underneath the deck?

What are the lighting options? Will we have to incorporate lights for evening use? Will the lights be standing alone or built into the deck surface (e.g. LED lights)?

What is the status of the underground? Is it sufficiently stable? How long has it been there? Are there any construction parts or tree roots running underneath the section where we plan the deck? How will we position and stabilise the structure underneath? Do we need to take out a lot of ground in order to stabilise it? What shall we do with the excess ground?

In case of a roof terrace: what is the top layer made of? How will we build anything on top of it? How can we fasten the boards without damaging the waterproof layer?

What type of joists will we be using? What are standard lengths?

How will we create shade if need be?

How will we make the transition to/from the house (elevation, pathways, …)?

Will we be needing additional heating?

What parts of the deck will be covered? How shall we make and anchor the construction?

Will the deck be built on level ground on sloping site? How high will it stand? Will we need a permit? Do we need to foresee any railings?

Once one has provided answers for such considerations, the design of the deck can be started.

However, first read the instructions of the selected wood plastic composite decking system again. Thorough reading of all manuals first will make for more profitable projects. Failure to do so may result in more difficult installations, unforeseen problems or even errors that may jeopardise the deck's long term integrity and/or the product warranty.

It all starts with a drawing…

Tip: take a (digital) picture of the spot and the surroundings where your deck is supposed to come. Have it printed with reduced contrast and with highly amplified brightness on matte paper. Now, with a pencil or marker, you can draw the outlines of your deck and the surroundings, such as plants, pathways,… This way, you can easily plan and correct your deck based on what it will look like after it is finished.

Physically marking out the area to be occupied by your deck with wooden pegs and string will help to visualise the size of the finished project. It might still change the way you feel about the paper design and bring new insights. It will certainly serve as a guide for preparing the site.
Now, the design phase can be concluded with a detailed frame and outlay drawing, taking into account the electrical and support requirements for your specific situation.

A new deck step by step

Leveling the site

If your site is lawned, the turfs are to be removed. Make sure that the site is level, slightly sloped (1 cm per meter of deck, towards the drain you foresaw during the design phase) for rain water drainage. Flat areas where standing water may gather should be addressed by grading or improved drainage. Mere evacuation of the water however is not sufficient: make sure that the space beneath the deck can be well aerated.
If your site is on bear ground, you may use a special sheeting to prevent unwanted vegetation from growing underneath your deck and showing up between the deck boards. Put this sheet before building your frame.

Creating the frame

Note: When installing heavy loads atop your decking project, a hot tub for example, it is important to understand the requirements of the manufacturer as they may express specific framing and support requirements.

One important decision to be made before starting the frame construction is the orientation of the boards, e.g. parallel or perpendicular to the house?

It may help to realise that, when looking at the deck, boards oriented from left to right give the impression of a broader deck, whilst looking at boards lengthwise gives an impression of more depth.

For the ground supports for your frame, numerous options are available.
Some of the most common are:

concrete foundation posts;

concrete slab;

layer of stabilized sand (i.e. with a minimum of 100kg/m³ of cement);

thick layer of gravel;

concrete pads;

wood poles.

When intermittent supports are used, additional remarks are in order:

dig them deep enough into the ground so as to get to the stable underground and not have longer term stability problems;

only use sufficiently rigid frame joists. Do not use any wpc (wood plastic composite) framing material in these cases, as they do not provide sufficient stiffness to cover the span long term and may eventually suffer from creep.

The framing joists should be put a maximum of 37 cm apart at centres, for residential use. Apply a maximum of 30 cm (1ft) centre distance for commercial use. These distances need to be corrected if the boards are not put perpendicular to the support beams.

When planning the beams' position, be sure to foresee support for the board ends: they should not extend further than 1” (2,5 cm) from the joists.

When installing blocking (cross connections between framing joists) for increased frame stiffness or for more intricate decking patterns, solid blocking (blocking laid on the flat) may inhibit water and/or air flow, which may give rise to problems later on in life. For best results when blocking is required, it should be installed ladder style.

When put on a stable ground, wpc support beams do not need to be fixed onto the ground. However, it may be preferable to fix the outermost supports to the supporting slab.

To level out the joists, plastic wafers or thin slices cut off a wpc board end can be used in case of wooden or metal beams. When wpc beams are used, they should be leveled out with stabilised sand so that their full length is supported.
For use only with rigid joists, plastic screwjack pedestals are available in variable heights that can easily be adjusted in height. Some models will even provide slope correction elements.
Note: In case you need to provide a hatch for inspection or cleaning below the deck, be sure to provide adequate supports for these shorter boards, without blocking the aeration air flow.

Storage and transportation

Store the boards in a dry shelter, well ventilated, away from direct sun exposure.

The wood plastic composite will expand when heated. For a uniform behaviour of all the boards after installation and in order to preview the appropriate gap (see below), it is recommended that all boards be used at the same temperature. Therefore, it is a good idea to keep the boards you will be using in a dry shelter, well ventilated and away from direct sun exposure before building your deck.

Also, the initial colour change of the boards can happen quite fast. Therefore, if pallets are stored out of direct sunlight, the deck will have an even colour right from the start.

Storing the boards horizontally, on evenly distributed supports, will keep them perfectly straight, thus making installation still that little bit easier.

Unload the products with care. The sides of the board, when hitting an obstacle with some force, may damage the surroundings or may get damaged themselves. This may make installation more difficult or induce product loss.

Mounting the boards

The frame is ready. Now we can start to put the boards. Let’s begin with putting them loosely into their place.

With every eco-Profil deck board, you have the choice between two possible sight surfaces, or the combination of both. The boards are symmetrical and mounting them either side is possible. However, during the manufacturing process, the boards are brushed. This process is directional and gives a preferential orientation to the wood fibres at the surface. This in turn may give a specific colour impression depending on the viewing angle, just like the poles in a carpet. For an evenly coloured deck, all boards should be oriented the same. A notch is extruded into the groove at one side of every board as a reference in order to see or feel the correct orientation. You may also gently slide back and forth with your fingertips in the length of the board to feel the difference in roughness.

If necessary, now is the moment to change the boards’ orientation.

Also, the natural fibres used during manufacturing may create slight colour variations between boards. Laying out the deck design beforehand may help ensure a proper colour mix.

The eco-Profil wood plastic composite materials can easily be cut, routed, sanded, or otherwise transformed using standard wood working tools. For cutting, it is recommended to use carbide tip blades with coarse teeth. Fine teeth blades typically give more rise to friction and thus wear more easily.

Fastening the boards

When finally fixing the decking planks, a number of attention points are in order.

1. Use fasteners that allow for the thermal expansion of the boards when warming up.

Contrary to natural wood, wood composite types of material tend to show variation in length rather than width and have a different behaviour in expansion/contraction.

Classical wood tends to have dimensional variations mainly because of humidity changes: it swells when humid, shrinks when drying out. Also, the moisture content may change significantly over the course of a year.

Wood plastic composites do not hardly pick up as much water as classical wood. Massive products like eco-Profil pick up moisture a lot slower, and less, than similar hollow profiles. The swelling in thickness and width are therefore more limited than with natural wood.

In contrast, the plastic matrix in the product tends to expand when heated. The over-all effect of this is much more pronounced and visible over longer lengths.

In order not to get tensions, leading to deformations of the boards, it is necessary to allow the boards to expand with increased temperature:

end-to-end gaps between boards;

gap between the first board and any obstacle, such as a wall, post or swimming pool edge

End-to-end gap (mm) between boards for an expected surface temperature increase to 60°
Board temperature during installation (°C)	Board length
Board temperature during installation (°C)	2,4 m	3 m	3,6 m	4,8 m
10	4	5	6	8
15	4	5	6	8
20	3	4	5	6
25	3	4	5	6
30	3	4	4	5
35	3	4	4	5
The decking must span at least three joists

Scarf cut

If you want these gaps to be less visible, use mitre cuts (see drawing) at these spots. An angle of 22° is recommended, as sharper edges may round off over time.

eco-Profil designed a specific stainless steel clip that allows the longitudinal movement of a board under varying conditions. We therefore recommend the use of these clips for fastening the eco-Profil boards.

Other fasteners may be used also. Just be aware that, for long term success, stainless steel fasteners and screws are necessary. AISI 304 or A2 steels are corrosion resistant and may be used for most outdoor applications. The heads of stainless steel screws tend to break off more easily than carbon steel, so be careful and use an electrical screwdriver in a slow turning position. Use the torque limiter on your power tool to prevent damage to screws and bit elements.
At butt joints, two fasteners are required per plank end.

2. Provide sufficient aeration

As stated before, the decking design should have foreseen sufficient slots for a ventilating air flow underneath the deck. This is not the time to modify the design or the looks of the deck in such a way that this air flow may now be obstructed.

3. Keep correct joist spacing

Remember that any board, also the very short ones, need to be supported by a minimum of three joists in order to prevent sagging or end ‘curling’.

Joists can be a maximum of 37 cm apart, centre distance, for residential applications.

When for instance laying the boards in a “chevron” or “fishbone” style however, typically they are no longer under a 90° angle on the support beams. Then, the joist spacing needs to be reduced. With a 45¨mounting angle, the joists can only be 30 cm apart, on centres.

Be sure to support the board ends: they should not extend further than 1” (2,5 cm) from the joists.

Final steps

Only moments now until you can enjoy your well deserved rest on your new deck.
The final touches to the deck can be:

trim the edges of your deck with a jigsaw or, preferably, a circular saw to obtain a professional looking even rim;

use a router or a sander to further round or chamfer the edges. It will look so much cleaner and, at the same time, be less prone to damage;

if a fascia board needs to visually embellish the side of your deck, you can cut a section off an eco-Profil wall cladding board of the same colour as your deck. The advantage is that these boards are quite flexible and may follow the sometimes intricate outer curves of your deck. However, remember to leave the necessary aeration slots at the bottom: skirting must not impede air flow. Pre-drilling and countersinking gives the nicest results when fixing the fascia boards.

with the cut offs, it is sometimes possible to build a flower box or some other add-on for your deck. Just be aware that the colour change of your deck board surface is accelerated by water and light, so move the pot around for a couple of weeks so as to obtain an even colour on your deck.