Building a deck – the substructure
Deck substructure
Once the foundation is finished and the joists are fixed to the walls of the building, it is time to build the deck substructure.
Cross or flush substructure?
The choice depends on the planned height of the deck. Installing a cross substructure (right) is the quickest and most frequently chosen method. If you want a lower deck, you can fit additional cross joists between the main joists (left).
Video by the manufacturer ESSVE, without English subtitles.
Installing the deck substructure
For fixing the cross joists we recommend WAF or ET-T screws. They need no pre-drilling and differ in appearance and installation method.
- The ET-T screw allows hidden fixing – it has a small concealed head.
- The WAF construction screw gives a reliable joint and has a flat head.
If you do not want to use construction screws, you can make the joints with timber engineering connectors and connector screws (photo on the right). The photo in the middle shows a joint made with WAF screws.
Installing a cross substructure
If you have chosen a cross substructure with cross joists, the best way to fix them is with ET-T screws or angle brackets.
Next steps of the guide:
Deck foundation
How do you build a foundation for a timber deck? It depends on the type of ground and on how the substructure is fixed.
Fixing the deck to the facade
A deck usually adjoins the wall of the house. The material of the wall and facade determines how, and with what, the joists are fixed to it.
Visible or hidden fixing of decking boards?
Before you start laying the decking boards, you need to choose the fixing method. Traditional fixing with screws driven from the top is the most common, but fixing with hidden screws has also become popular recently.
Choose screws of the right quality
For a durable deck, it is important to choose a screw of the right quality with suitable corrosion protection. The choice is affected, for example, by the environment, the type of wood and the type of deck structure.