15. Sagging in floor joists is typically caused by

A. oversized joists.
B. undersized joists.
C. improper nailing of sub-flooring.
D. improper moisture content of the wood

i think it's D.

3 answers

Yes, I have seen "juicy" wood also called "lake dried" installed as joists. I left that job. Undersized joists would never make it through the frame inspection.
Thanks...
It's B. Undersized joists.Just did the test!