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 your decking material.
Refer to the Decking Span Table to determine what is the maximum distance that your chosen decking can span between joists.
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.
The Joist Span Table below will assist in determining the
maximum length your joists should span between supporting beams,
bearing in mind that these distances reflect the strength capacity of
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”!
Deck Joist Span Table
**Table does not account for overhangs.
||Maximum Distance Between Posts or Supports