You are in the middle of the city, in the midst of a whole bunch of cell phone towers. From your car to the entrance to your building, you have wonderful 4G or 5G signal. You duck into a building and all of the sudden you can’t make a phone call. The wall of that building and what’s it made of make a big difference in whether you can get reception. What if they put up a new high-rise between you and that great cell tower? There’s no better way to learn how to block cell phone signal.
Same goes for your house. What if you buy a house with a shingle roof that gets great reception and you decide to upgrade to a metal roof and all of the sudden your phone doesn’t make great calls anymore? That roof makes a difference. If you are in the mountains and get a cell phone signal around this curve, but not that one, trees or a hill may be blocking the signal as well.
What Blocks Cell Phone Signals?
Cell phone signals can be blocked a little or a lot depending on the type of materials used in construction of the building. Materials that do not conduct electricity like wood, drywall, plastics, and glass will impede a cellular signal, but not block it. Materials such as tin, copper, silver, aluminum and others can completely block the signal. Let’s investigate some of these materials that block cell phone signals.
In your Home
Besides the location of your home and whether it’s in the valley or on the top of the hill, what your home is made of makes a difference. Most homes are made of wood, plywood, fiberglass insulation and glass. For brick or metal homes, we will discuss these in the office section below, but of course they act the same no matter what building they are used in. Each of these has an effect on whether the cell phone signal makes it into your home office. Add them all together in the construction of your home and you will see all the ways building materials block cell phone signals.
Solid wood in your walls, ceilings, doors and even furnishings reduce signal by -5dB to -12dB. Plywood is thinner and can only reduce the signal by -4dB and -6dB.
You might think that signals can pass right through glass, but clear glass actually refracts the signal causing a loss of about -4dB. If you have tinted glass designed for energy efficiency and privacy (low-e glass), this rate of loss is a staggering -24dB to -40dB.
Insulation and Drywall
The more layers of building materials, the more signal is blocked. Fiberglass is quite porous at -2dB, but add drywall and the loss is -4dB.
In the Office
Office buildings add more robust and longer-lasting materials such as metal, brick and concrete. We already talked about glass, so imagine the high-end glass materials in commercial construction as well. These are even better at blocking signals. Some buildings are purposefully constructed to block cell phone signals for security.
Next to wood, metal is one of the best materials to block cell phone signals. Between -32dB and -50dB of signal is lost trying to get through a metal barrier.
If you want a room that blocks cell phone signal, create it out of cement or concrete. Between -10dB and -20dB is the average loss. Cell phones work poorly in basements and underground parking structures for this reason alone.
Classic homes and old buildings with a lot of character are built of brick. Expect loss of -8dB and -28dB.
What Do These Numbers Mean?
We have a whole article about dBm but, in short: cell phone signals operate at frequencies between -50dBm and -120dBm. The lower end of the spectrum at -50dBm is basically equivalent to 4 bars on your cell phone. -120dBm is basically no signal. If you measure the cell phone signal outside and the frequency says -60dBm, that’s pretty good. Now you walk in a building made of wood and insulation, you are losing several db. Depending on furniture and how many walls you are behind, the signal strength might have reduced to -80dBm or less.
How Do I Get Better Cell Signal?
You found the perfect house or location for your business and the building is made of brick or cement. Do you choose another site? No! First, check the cell phone signal inside. These loss rates are guidelines and whether your signal is degraded or completely lost indoors, is quite variable. Depending on your internet needs, you might be just fine.
If you are in an office building, there are requirements for construction that require emergency systems and services to be able to work everywhere. Your building manager has probably installed boosters and amplifiers for great signal. Check this before signing a lease agreement for office space.
Add a Signal Booster
If your signal is inadequate at home, you can add a cell phone signal booster! A cell phone signal booster is a great way to get good cell reception inside. If you have a great signal right outside the door, install an antenna facing in the direction of the strongest cell phone tower. Run the cable inside and the signal booster can project that signal through the building. A Wi-Fi extender can get it to the impossible to reach places. This way you have privacy and can still manage your devices or network indoors.
The point is, no matter what materials were used in the construction of a home or office building, there are ways to get the service you need or want. (And now you also know how to use materials to block a cell phone signal as well for privacy in your Zen meditation room.) Just be aware of the effects of choices and explore solutions.