Wi‑Fi through concrete walls and floors
Dense concrete is one of the building materials most likely to make placement—and wired backhaul—matter.
Concrete can be a high-loss barrier
Cisco’s current RF reference gives concrete around 12 dB as a typical attenuation example and notes that metal content matters. Measurements of reinforced concrete can be much harsher. The practical lesson is not to memorise one number, but to treat dense concrete as a barrier that can dominate the link budget.
Reinforcement changes the picture
Rebar, mesh and other conductive material can add reflection and absorption. Two concrete walls that look identical architecturally can behave very differently to Wi‑Fi. This is a major reason predictive browser tools must be labelled as planning aids rather than survey instruments.
Cross the barrier once if possible
If the building has a difficult concrete core or floor slab, it is often better to get Ethernet across that barrier and create a new access point on the other side than to force every wireless packet through it repeatedly.
Stairwells and open routes can help
Radio does not have to travel through the shortest geometric path. An open stairwell or doorway may provide a better propagation route than a direct line through reinforced material. Test access-point positions near those openings.
Related tools and guides
Wall-loss calculator · Mesh node calculator · Router placement guide