What is the recommended ceiling joist spans on new home construction - 16 in or 24 in and what are the maximum spans for each?

16"oc for stick framed and 24"oc for trusses.

The maximum span for a 2x6 16" oc (typicall ceiling joist) is 13'9"-18'9" depending on the species of wood and the grade used. Hem fir ranges from 10'6" to 11'3" and spruce-pine-fir ranges from 13'9" to 16'11"

For 24"oc the spans vary from 11'2" to 16'4". Hem fir ranges from 11'2" to 15'6" and spruce-pine-fir ranges from 11'2' to 15'2".

These numbers are for uninhabitable attics without storage