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These 3 Materials Are the Worst for Wi-Fi Signals

Dense building materials like concrete and metal can block or weaken Wi-Fi signals.

Key takeaways:

  • The thicker building materials are, the harder it is for radio signals to pass through them.
  • Interference caused by structures and objects lead to slowdowns and shorter Wi-Fi ranges.
  • 3 of the worst building materials for WLAN performance:
    1. Metal
    2. Concrete
    3. Plaster with metallic mesh

Internet issues can be frustrating, not to mention terrible for productivity. And when something goes wrong with the Wi-Fi, interference could be the cause.

Interference happens for many different reasons, from poor network planning to a sudden influx of devices causing congestion. But, if you notice that connections are dropping or slowing in certain areas of a building and not others, the culprit could come down to structural materials and equipment.

Why would building materials cause interference? And which ones interfere with Wi-Fi signals the most? Let’s walk through some of the basics.

Why materials impact wireless signals

Wi-Fi signals are transmitted between access points and devices that search for the signal and connect. This all happens via the electromagnetic spectrum. There must be a transmitter and a receiver—an access point and a client—that communicate via radio waves, electromagnetic beats that travel at the speed of light.

These radio waves must have a clear path to successfully transmit signals. When something is blocking that path, signals are interrupted and become weak or completely impeded. This leads to poor connectivity.

Roadblocks can include other radio waves from nearby devices, physical objects and equipment in a space, or the building materials that make up the structures around us. The less porous a material is, the worse the Wi-Fi connection will be. You could see shorter ranges and slower speeds and when planning a network, all these factors must be considered to ensure the best performance.

3 of the worst building materials for Wi-Fi

Not all structural elements or objects are going to have the same impact on Wi-Fi transmissions. But there are a few that you should avoid or be aware of when planning. Here are three of the worst: 

1. Metal

Metal poses the biggest issue to Wi-Fi signals. It conducts electricity, meaning it can absorb energy or electromagnetic waves. Radio signals degrade as they try to pass through metal objects, leading to network drops and slowdowns.

Pay attention to where metal may be hiding if you’re experiencing inference but can’t figure out why. Are there metal doors or walls? Are the blinds metal? What about equipment in the spaces where the signal is trying to reach? Are there elevators between the access point and devices?

Sometimes, there are metal components in floor heating systems. So, if you’re trying to get your signal to reach through multiple floors, that could be the issue. 

2. Concrete

Concrete is another dense material that is hard for Wi-Fi radio waves to get through. Lots of buildings have concrete walls, floors, and other elements that quickly create problems when devices are trying to connect.

One study conducted by the National Institute of Standards and Technology found that 203mm concrete created a loss of 55,1581 decibels at 5 GHz. Reinforced concrete, brick-faced concrete, and brick-faced masonry blocks were also some of the worst materials for Wi-Fi, according to the study. And the thicker the concrete, the more challenging it is for waves to get through the materials and reach a device.

Some bricks are more porous than others. But because brick is still fundamentally a dense material, Wi-Fi will usually have trouble penetrating it. 

3. Plaster with metallic mesh

Plaster is commonly used for walls and ceilings in buildings and homes. It isn’t as bad for Wi-Fi as concrete and metal, as it’s not very thick. But plaster can still interfere with Wi-Fi signals through its common cement-based composition. And plaster often covers metal laths or mesh used as bases for its application, which can contribute even more to blocked signals.

What materials are OK for Wi-Fi?

While any material or object in a building could provide a slight obstacle to Wi-Fi signals, there are certainly better structural elements than others. Here are a few materials that can be more easily penetrated:

  • Drywall
  • Wood, especially lighter woods like plywood
  • Glass

These materials will have little to no effect on Wi-Fi most of the time. However, note that tinted glass can have metal elements, so darker windows could pose an issue for the network, and double-glazed glass could be a bigger barrier to signal transmission. Wood is generally not a huge challenge for Wi-Fi, but timber walls have been found to block or reduce Wi-Fi signals.

Remember that interference can also be caused by nearby signals and devices. The 2.4 GHz band is particularly susceptible to this kind of interference, since it has fewer non-overlapping channels and many devices like Bluetooth radios, microwaves, baby monitors, and many others are on this frequency.

Address interference with more visibility

Factoring in building materials and equipment can help improve WLAN performance significantly. Watch for metal and concrete first and foremost, but also stay mindful of other substances that are dense and could be impacting radio transmissions.

When you need to know what’s happening with your network at a given moment, wireless experience monitoring increases visibility so you know the root cause of a problem and can address it faster. 7SIGNAL’s platform gives you the power to continually test the Wi-Fi, gather key data points, and monitor how end users are experiencing the connection at all times. And when connectivity issues seem to arise in some areas of a building but not others, materials-based interference may be the culprit.

7SIGNAL® is the leader in wireless experience monitoring, providing insight into wireless networks and control over Wi-Fi performance so businesses and organizations can thrive. Our cloud-based wireless network monitoring platform continually tests and measures Wi-Fi performance at the edges of the network, enabling fast solutions to digital experience issues and stronger connections for mission-critical users, devices, and applications. Learn more at www.7signal.com.