From Liquipedia Warcraft Wiki
The Lumber Mill is an alternative drop site for wood. It is also where technologies can be researched to improve Human lumber harvesting and the sturdiness of Human buildings.
|Balance Patch History|
|Patch Version||Balance Changes|
|1.10|| Lumber Mill cost reduced to 120 from 145.|
Lumber upgrade now gives +10 lumber capacity per level of the upgrade, up from +5 lumber capacity per level of the upgrade.