Have you looked up the house to see what if any permits have been issued?
If I saw some major project like this happening and learned it was not permitted, I'd call it in ASAP. I don't much care if somebody puts up a fence without a permit, but if you're doing structural work, electrical work, gas-line work, etc. permitting means inspections, which means some level of assurance that the project won't endanger health and safety of occupants and neighbors down the road.