The Grovetender is assigned to help you with that process. In conjunction with that, they focus on finding and freeing builders and loggers that day.
Vor'ruk, using his extensive war knowledge, works on "point" defenses. He understands that a traditional wall wouldn't be of significant value during a siege of the kind that is likely to come from the current enemy. And that wall would consume a large amount of our time and resources. The Orcs and Gnolls work on fortified locations scattered about that can be used as shelter and fighting locations for the towns inhabitants and defenders. Keeps, Reinforced buildings, and warehouses paying special attention to angled, thick, roof timbers. Usually used to fend off catapult shot, would work well then they cowered sky giants show. If possible, each has a location for the people to shelter in as well.
Rompie at the end of a day, if no attack has come, he'll use Animate Plants from the staff in coordination with the local clerics to move sentimental trees, or other plants that might be in danger to clear the way for defenses.