Which Building Materials Can Block Wi-Fi Signals?

Bar chart visualizing wifi signal loss by building materials, ranked from least to most.

Do you have poor coverage in parts of your home? Here are some examples of how much Wi-Fi signals are weakened when passing through walls.

Are you curious why a part of your home, or even an area just outside the house, has poor Wi-Fi reception? It could be due to the material used for the wall, or other physical barriers that block or weaken Wi-Fi signals.

Worst Signal Loss: Concrete

Concrete, with and without metal reinforcement, is one of the worst building materials for wireless signals to pass through, but masonry block and bricks can also be serious barriers for Wi-Fi. Plywood and drywall come close to zero signal loss in tests.

Signal Loss by the Numbers

The numbers in the graphic above and the table below are based on the findings in extensive experiments performed by the US National Institute of Standards and Technology.

MaterialAttenuation in decibels at 5 GHz
Concrete (203 mm)55,1581
Reinforced concrete53,7989
Brick-faced concrete39,8953
Brick-faced masonry block32,6320
Concrete (102 mm)26,0008
Masonry block14,9250
Drywall~ 0
Plywood~ 0

These figures are taken from the report “Electromagnetic Signal Attenuation in Construction Materials”, NIST Construction Automation Program Report No. 3 from the National Institute of Standards and Technology.

Geek’s Corner

You can read the full research report here: http://fire.nist.gov/bfrlpubs/build97/art123.html

Article by Jorunn Danielsen