What causes the most signal attenuation, based on the wireless design tools?

Cinder block walls cause significant attenuation due to their density and moisture content, but their porous, non-conductive composition still allows more signal penetration than solid metal.

Metal doors act as near-complete RF barriers due to their high electrical conductivity, which causes the signal to be reflected and absorbed rather than transmitted, resulting in the highest attenuation of any common building material listed.

Glass walls are largely RF-transparent and cause only minimal signal loss, making them one of the least attenuating indoor obstacles.

Office windows, like glass walls, transmit most RF energy with very little absorption or reflection, resulting in negligible attenuation.