There is no apparent trigger for this task. It may be completed at any time during the first visit to the Grand Staff Construction Base.
- From the outside, on the upper level to the northwest, talk to each one of the guards to have them start moving around.
- Sneak past the two guards who are guarding a large assortment of crates.
- Descend the ladder to enter the Building Material Warehouse.
- Exit that room to the south to enter the Engineer's Resting Room.
- "Grab" and "Push" two boxes to clear a path from the main section of the room to the door you just came from.
- You can access the Building Material Warehouse without having to sneak past the two guards from the upper level.