Several Factors Determine The Deck Joist Span For Your Deck
The proper deck joist span (distance between supporting beams below the joists) for your deck should be known before you start building and is needed to draft your deck plan. The spans of joists varies based upon several factors: joist size, spacing between joists, decking material and wood species.
First Step: Select a Wood Species
Select which kind of decking material you will use for the finished deck surface. See the Decking Span Table to determine what is the maximum distance that your chosen decking can span.
For example 2x6 materials can usually span 24” without any noticeable deflection and still support a significant load. However, lumber prices are rising and therefore it is more common to see 5/4”x6 deck boards that should not span more that 16” and usually 12”.
Once you know your decking material and its maximum recommended span you can then refer to the deck Joist Span Table below.
Second Step:
Refer to the Joist Span Table below to assist in determining the proper span of your joists between beams, bearing in mind that these distances reflect the strength capacity of the joists only. You must select a joist span that corresponds with the maximum length your decking can span.
Also, remember this simple concept to assist you. The closer you space joists together, the greater length you can span joists – up to a point. The numbers in this chart indicate the maximum span you can use based on the type of wood and the spacing you have chosen. You are now “good to go”!
