Actually, the unloading it usually done by the delivery man who beings the material. Wood lumber is not really a problem. It's the sheetrock and plywood panels that are the heavy materials.
Unloading from the truck isn't what I was referring to... it is the moving from the pile of lumber to the back of the site - or to the 2nd floor, or wherever.
And the point is that you can pick up illegals at a number of locations and pay $25 per day plus food for whatever work you have.