Bad Phone Coverage? These Materials May Explain It

Many people are familiar with the experience of climbing inside an elevator and dropping a mobile phone call within a few seconds. Heading into the basement can cause a similar problem. If the radio waves that create the mobile phone signal can pass through almost any surface, why is signal strength still such an issue?

The fact is that there are many factors that affect the kind of signal strength a person might get in a building, including building materials and even weather patterns. A series of obstructions could create a mobile dead zone, even if the individual materials are not particularly problematic by themselves. When considering new improvement projects in your home, keep aware also of what the results of those projects can do to your cell signal.

What Determines Signal Strength?

People who watch the number of dots or bars on their phones as they go through town may notice that there are several points in time when the signal will slow or drop, and it may not be obvious why that is. The truth is that the different carriers decide how they want to interpret the strength of the signal in any particular area, and the same signal could vary quite significantly from one carrier to another.

On top of this variability, tangible obstructions make it more difficult for the signal to reach the person, or to get back to the tower to connect a call. Every material that the signal must pass through can decrease the number of decibels needed to maintain an ideal connection, and some are worse than others.


It is perhaps unsurprising that something as solid and strong as metal could be the biggest disruptor of mobile phone signal in a building. Even when metal is lightweight and used sparingly throughout a building, it can still reflect or distort a radio signal. This is why many people who install the increasingly popular styles of metal roofing find that their cellular signal is no longer as good as it once was.


Getting new windows with technology to improve energy efficiency could also have a negative effect on the quality of mobile phone coverage. Old windows have little in the way of sun-blocking features. This means that they are less-efficient at blocking solar heat gain, but more effective at allowing the cellular signal through the building. Tinted windows and windows with a low-e coating can reflect that cellular signal right back out, inhibiting mobile phone access on the inside.


Of course, there are some materials that may seem like obvious issues for those who want to improve their cell phone signal. Concrete and cement are designed to be hardy, heavy, and difficult to deconstruct. They are not quite as problematic for radio signals as metal or treated glass windows, but they can still shave a bar or two off the coverage for the space.


Ultimately, most solid materials can serve as a buffer between a person and the signal coming from the local cell tower. Like concrete, brick is a thick surface that provides some insulation between inside and outside. It does not have as much potential to block or reflect the signal back, but still serves as a common source of disruption in coverage.

Other Factors to Consider

Although many of the possible signal problems people face on a regular basis occur as a result of the materials in the building, they should also think about other common causes. Anyone who has driven into a canyon and lost coverage knows that hills and other natural aspects of the area can affect a signal. Manmade obstructions, such as other buildings made of similar materials, might pose an even bigger issue.  In addition, the position of the tower in relation to the building may reduce signal strength, if the building is near the limit of the tower’s reach. Even a rainstorm or tree in full bloom could temporarily impact the signal’s ability to get through.

As it turns out, almost anything, from trees to glass, can turn a phone with plenty of coverage into something more resembling a paperweight. By understanding the types of materials that can block a mobile phone signal and other location-specific concerns, people can plan for a possible disruption in coverage and find alternatives that can solve their problems maintaining an effective signal.