My home is sheet metal siding, metal roof ("metal buildings" standard cheap barn/shop type construction), with a 2 inch braided RF strap run along the base of the wall panels and to the house ground. We have many windows, and near those is the only place you can get any external radio signal.

My primary intent in building this way was to contain computer noise and be able to play with radio scanning using external antennas. It certainly worked for that. Its not a Faraday cage, but it's remarkably effective.