Why does the maximum deck overhang sometimes decrease with joist spacing


The deck construction guide for my area contains this table:

enter image description here

enter image description here

Look at the "Allowable Overhang" columns. It's odd that a wider joint spacing (24") permits a longer overhang.

For example, look at the row for 2×12 fir joists. At 12" O.C. spacing, overhang can be 4'4". At 24" spacing, this decreases to 3'3".

Now look at 2×8 fir joists. At 12" spacing, overhang can be 1'8". Increasing the spacing to 24" increases the allowable overhang to 2'2"!

This doesn't make sense: I'd think closer joist spacing means more load bearing capacity, allowing for longer overhangs. Even more confusing is there's no consistency between joist sizes. What gives?

Best Answer

Looks like data entry error to me. The values were reversed for several rows at some point.

Considering that they spelled 'fir' as 'fire' in one case, one can assume that accuracy was not a high priority here. That's not a flush beam, either, nor is '2x8' a 'length'.