Decking construction – tips and tricks

Please note: The following tips and tricks serve as a recommendation to ensure your wooden decking lasts for a long time. They are no substitute for state-specific regulations, technical rules and standards.

Wood is a natural product.
As the weather conditions to which the wooden decking is exposed every day differ from place to place, varied greying and possibly cracks and splintering can occur. It is essential to regularly inspect, maintain and refurbish the wooden decking.

The construction determines the service life.
Constructive wood protection is the basis for long-lasting wooden decking. All of the decking surfaces that become wet or bear water when it rains must be protected with water drainage. This must have a slope of at least 2%. Sufficient air circulation should also be provided to protect against waterlogging and moisture traps. Preventing wood-to-wood contact also helps. All of the components of wooden decking must fundamentally be able to dry quickly at all times. If these structural specifications are complied with, the service life increases and the likelihood of cracks and/or splintering decreases.

The base is crucial.
Selecting the right base is generally very important during installation. No matter whether it is on a surface that is impermeable to water such as a roof terrace or on a water-permeable surface such as a gravel bed. The base should be stable, protected against subsidence and drain rainwater away. An even discharge of water to prevent waterlogging is ensured with a small slope of min. 2%. A protective fleece layer can be incorporated to prevent plants from growing underneath and causing dampness under the decking.

The spacings must be right.
When assembling the decking, the right spacing between the substructure and base as well as between the decking boards and the substructure is very important. There must be adequate air circulation. For sunken decking, we recommend a construction height of at least 150 mm. A joint spacing of at least 6 mm is very important both to drain water away without any problems and also to compensate for swelling and shrinkage. It should also be ensured that a ventilation opening of at least 50 mm is provided when fitting side cover boards.

Slope increases the service life.
Both the base and the decking must be able to drain water away. This is why we recommend fitting all water-bearing surfaces, i.e. also the decking surface, with a slope of at least 2% in the board direction. This prevents waterlogging and the wood can dry out at all times, which significantly increases the service life.

Comply with directives!
We fundamentally refer to the state-specific specifications. Our tips are based on the specifications of the Bund deutscher Zimmermeister (Fachregeln des Zimmerhandwerks Teil 02 – BDZ ) and the Verband Europäischer Hobelindustrie (Fachliteratur: VEH Holzterrassen).

6 tips for constructing your decking

By following these tips, you will increase the service life of your decking.

1. Construction height

A construction height of over 100 mm provides optimum ventilation for the entire construction.

2. Support spacing

The spaces between the supports should be chosen in such a way that the substructure is prevented from sagging. If the supports are too far apart, the decking will feel spongey underfoot and it can cause the decking connectors to be overloaded.

3. Side facings

Side facings are to be added in such a way that ventilation is ensured for the entire construction, e.g. with perforated stainless steel plates.

4. Raised installation

A raised installation [ventilation layer] of at least 6 mm provides structural protection and reduces swelling and shrinkage. Shearing effects that act on the fixings are also minimised. Direct wood-on-wood contact is to be prevented.

5. Support points

Support points are to be created in such a way that a maximum level of stability is ensured in the long term.

6. Edging and borders

Side decking edging and borders should not impair the ventilation of the entire construction.

The correct assembly

Assembly on a gravel bed

Assembly on concrete or tiles

Joints and spacings

Wood moisture is to be checked before installing the boards. The right initial moisture ensures that the decking will be fault-free and function in the long term. The joint spacing X must be at least 6 mm to prevent swelling and shrinkage. Creating joints on just one substructure increases the absorption of water in the end-grain area. This causes excessive swelling and shrinkage of the boards, promotes dirt accumulation and does not allow the necessary fixing spacings to be provided at the ends of the boards.

The substructure must be arranged and oriented precisely. Irregularities in the substructure lead to subsequent defects and damage to the entire decking construction including the fixings.
Recommended distance from centre to centre: 400 mm for boards up to 20 mm thick / 450 mm for boards 25/26 mm thick
Short boards (Y) are to be installed with at least 3 substructure planks.