I just tore off the old decking from my cabin's deck. The joists are set 24" on center as opposed to the 16" on center that were in the specs. Should I take all the joists out and replace all of them, or add a new joist between each existing joist? The deck is about 12 years old and some of the joists have to be replaced due to rot.
The wider spacing is less rigid, you may feel a little flex as you walk. I do not like the flex so I used 16" centers. Also , if you use 2 X decking instead of the recommended 5/4"decking, it will be more rigid and last longer. My 2X decking is 20+ years old in good shape in a warm ,wet location; I have replaced about 5% because of rot ( under planters).
We design from the top down and build from the bottom up.
So, depending on what type decking you use, you can the decide what size and spacing of joists to use.
For 5/4 material I’d use a 16” spacing. For 2x material (1 1/2” thick) I’d use 24” spacing for plastic decking boards and 36” spacing for Cedar, Redwood and pressure treated boards.
The size of the joists will be determined by the span of the joists. We’d need more info to determine that...
as opposed to the 16" on center that were in the specs" ??
Someone did not follow specs ??
Since you have to replace some of the joists then you might as well take them all out and do it right this time with treated joists. ( 16" OC, unless you want 12" OC)
If you take them all out to start over then that gives you a chance to inspect the quality of all the other components to make sure any problems are addressed.
NOTE: The word “right” in the phrase “do it right” is referring to Alaska Man’s opinion of what right is for deck joist spacing.
No other participants were harmed in anyway in the formation of this opinion.