This has made the rounds before on the internet. People used to have radios with total lead painted houses, probably on the outside too. Yet most homes had AM radios against a wall with nothing more than the loop antenna built into the radio. The entire house would have to be made of continuous lead sheets, no gaps, to do anything useful in blocking frequencies. Possibly, a small chance it could diminish higher frequencies but they they would still enter and leave, the walls and windows would have to be solid lead.