Likely wood, concrete would probably attenuate a fair amount but still penetrate. Modern glass-walled office buildings with metallic coating for UV and therma

Likely wood, concrete would probably attenuate a fair amount but still penetrate. Modern glass-walled office buildings with metallic coating for UV and thermal insulation would probably reflect or attenuate the signal enough to be unusable. Walls with metal lattice in them (plaster, stucco) might also be difficult to penetrate.