Wood-framed building deconstruction : a source of lumber for construction?

The sounds are much like those found at any building site. Hammers pounding. Saws whining. Lumber in motion. However, everything here seems to be in reverse... windows and doors are being unhung rather than set in place, nails are being pounded out of boards instead of into them, lumber is being stacked up, banded, and hauled away rather than delivered and unstacked. This is the scene at a wood-framed building deconstruction site.