Can municipal authorities get warrant to search suspected building site in U.S.?
Laws and rules vary widely across the country. Most towns or counties have the right to inspect the interiors of dwellings for the purpose of tax assessment, health and safety conditions. Construction inspections fall into all these categories. Insurance companies may require inspections to assess their risk of loss.  The purpose of most govt inspections is to assure that work is done to current standards and does not create a fire or health hazard to the occupants and surrounding properties. In my business, I have seen it all, dangerous wiring, leaky gas lines, sewer gas infiltration, unsafe woodstove and heater installations and substandard structural framing.

If a homewoner refuses to allow any such inspection requested for just cause, they may face fines, loss of insurance, stop work orders, loss/denial of occupancy permit and in extreme cases forced eviction by law enforcement.