Timber Decking Joists

Decking joists are the structure upon which your deck boards should be laid. The joists are usually supported by beams which are attached to posts, thus creating a raised deck.


Determining the joist's strength, durability and spacing can be vital to the success or failure of your decking project.

Many projects assume that because the joists are never seen, there's no need to pay attention to their specification. However, the cost of replacing rotting joists includes lifting all those beautiful hardwood deck boards, and potentially damaging them in the process.

As a general rule, go for joists that are as durable as possible. This will usually mean going for timber that is suitable for Use Class 3 or Use Class 4. If pressure treated, please ask for service life guarantees.

The distance between the joists will also ensure your deck area is stable and safe to walk. Here's an example of span tables for C16 softwood:

For further details on how to install your deck, please check our simple guidance sheet:

If you'd like to discuss your project in more detail, including water-based decks such as piers and pontoons (we supplied all of Hastings Pier decking and joists), please contact us on 03456381340.