If you are trying to protect yourself from wifi radiation (RF radiation) you might be wondering whether wifi signals can travel through walls.
Let’s take a closer look at 9 types of walls and how effective they are at blocking wifi radiation.
Table of Contents
This article was reviewed and fact-checked by James Willams from TechPenny on September 18, 2023. He’s a tech expert who also happens to know a good deal about EMF and electricity.
Abbreviations used in this article:
EMF: Electromagnetic Fields (All types of radiation)
RF: Radio Frequencies (Radiation from wifi, cell towers, and other wireless technologies
V/m: Volts over meters (How we measure RF radiation)
How Well 9 Types Of Walls Let Radiation Through
We have several types of walls and they are not born equal when we are talking about their ability to block EMF radiation.
The waves we are talking about when we look at wifi signals are the frequencies between 2-5 GHz. This is also so commonly known as “microwaves” or radio waves when we get a little more technical.
These types of waves will very easily pass through most materials.
The signal from our wifi routers is a strong radio signal that can easily pass through walls much like you can receive an FM radio signal inside your house. That being said, the different types of walls will impact the radiation a little bit as we will see here.
Let’s start with an ordered list of how good (and bad) different types of wall material are at blocking wifi signals:
Do PLYWOOD Walls Let Wifi Radiation Through?
I just tested my wifi router with my EMF meter and found that a 1.5-inch plywood wall weakened the wifi signal a little bit.
At a close-up distance of 2 feet, I measured that the signal was weakened around 15% when I inserted the wood between the router and the meter.
This is probably not bullet-proof evidence but it shows how a thin wooden wall will impact the wifi signal and the EF radiation a little bit.
Do BRICK WALLS Let Wifi Radiation Through?
Bricks are typically made of clay, sand, quartz, flint, or a combination thereof. I other words, brick walls are made of stones and clay.
So how well do clay and stone stop RF radiation?
Brick walls are much more efficient at blocking RF radiation than wooden walls and plaster walls.
A brick wall will not stop the radiation completely (few things will!) but the signal is weakened.
In general, you should expect one brick wall to the majority of the radiation from a 5 GHz router while a 2,4 GHz router will be able to send the radiation through the first brick wall but probably not the next. This also holds true in our house. We have a rather strong wifi signal through in the first room next to the router and in the next room after that, the signal is very hard to catch.
So, the short version here is that a standard brick wall will weaken the wifi signal (and the EMF radiation) around 50%. When you add another wall the signal will be weakened again but the distance here also plays an important role, as we will look at below.
This also has to do with another factor which is the distance added when you move to the next room.
When you double the space between you and a radiation source you will lower the radiation four times. This law is known as “the inverse-square law”.
Do PLASTER WALLS Let Wifi Radiation Through?
One of the most common types of plaster walls is gypsum plaster walls. It’s a white type of cement that is made of the mineral gypsum.
This composite is very bad at blocking wifi signals and radiation. Depending on the thickness of the wall it might weaken the signal a tiny bit but the radiation is not lowered to safe levels by inserting a plaster wall.
Plaster walls are much like concrete as we will look at below. So read on to learn more about how your plaster walls will work as an RF blocking medium.
Do CONCRETE Walls Let Wifi Radiation Through?
Concrete will also let the wifi signal pass right through and with it the RF radiation. However, it does weaken the signal a little bit.
But when we are talking about reinforced concrete the signal and the radiation will be weakened substantially. This is because we add metal into the equation.
When we talk about armored concrete (reinforced concrete) we will typically have an iron core that is inserted into the concrete to make the construction stronger. This
Does DRYWALLS Let Wifi Radiation Through?
Drywall is placed in the middle of the scale we listed above. Right between how glass and wood (almost) won’t reduce the RF radiation from routers and how concrete will block 50-70%.
It’s not a linear line of dots so we cannot assume that drywalls will block exactly 25% but it’s a pretty good guess.
I have several tenants in the basement and the wifi connection is much better through the drywalls we set up there than between the floors. The floor separation is made of concrete and that blocks around 50% of the wifi signal and the radiation.
Can Neighbors Wifi Radiation Affect Me?
When you live in a city (like me) you will typically be able to detect a lot of wifi signals when you are trying to connect your phone or laptop. This can be very alarming to look at when you are informed about EMFs and RF radiation.
But how worried should you be about your neighbor’s wifi signals?
You normally don’t need to worry about RF radiation from the wifi signal from your neighbors. This is because wifi signals follow what we call the “inverse-square law”. This law tells us, that when you double your distance to a router you will decrease the signal (and the radiation) by four times.
This also means that you don’t have to worry too much about all these signals.
Unless the router is within 5-20 feet you don’t need to worry because the RF radiation will be below the 0.2 V/m that building biologists tell us to stay under.
This is unless we are talking about a very strong wifi signal or if there are access points inserted between you and the router.
These access points will typically emit the same levels of RF radiation as the wifi did at the original source.
How Do I Block Wifi Signal From Outside?
If you do have a strong Wi-Fi signal next to your building you will need to take precautions in order to protect yourself inside your house. This is also the case if you are living next to a cell phone tower will radiate EMFs toward your house.
So what can you do to protect yourself?
If you want to block the Wi-Fi signals from outside you will need to use a special type of paint also known as Yshield paint.
This is a special type of paint which is grounded by inserting a wire into the ground.
You will simply have to paint the walls that radiation source. You will do this by using this paint as a prime coat and you will only have to apply one layer for a 99% effective protection toward RF radiation, which is the type of radiation we get from wifi signals.
You might not have tried to ground the wall before and you do this by inserting a special grounding strap to the wall BEFORE the paint is applied.
It’s important to put on the strap before you start painting because it’s only the upper side of the strap that is conductive.
According to the manufacturer, the grounding process only affects the lowest part of the radio frequencies. It doesn’t have any effects on the RF radiation which is the type of radiation we are looking at regarding Wi-Fi signals.
How Can Wifi Signals Travel Through Walls?
The short answer is that they can do this much the same way as light can travel through glass. Or like sound waves can travel through walls.
Just because we cannot see through a wall doesn’t mean that radiation waves cannot travel through walls.
The reason the wifi signal can travel through a wall is to be found in the construction of the atoms in our building materials. If we were using thick metal walls, our wifi signal would not be able to travel through. But as we are talking about building materials (like mentioned above) the wifi signal can actually travel through, at least to some extent.
The way the atoms in our building materials are structured allow for wifi signals to pass right through.
There are certain types of metals such as gold and silver that will block both radio waves very well. These are typically not used in walls for obvious reasons.
How Do You Best Block Wi-Fi Signals?
Blocking or shielding your living space from a neighbor’s Wi-Fi signal (RF radiation) can be a challenging task, mainly because Wi-Fi signals are designed to penetrate through various materials to provide widespread coverage.
Nonetheless, if you feel the need to block or minimize the Wi-Fi signals from entering your premises, here are several strategies you might consider:
- Metal Sheets or Foils: Materials like aluminum foils or metal sheets can be used to create a barrier on the walls or windows facing the source of the unwanted Wi-Fi signals.
- Metal Mesh Screens: Installing metal mesh screens on windows can potentially block or reduce the penetration of Wi-Fi signals.
- RF Shielding Paint: This is a special type of paint that contains particles that can attenuate RF signals. Applying this paint to the walls can reduce the Wi-Fi signals from penetrating through.
Distance and Obstruction
- Relocate Living Spaces: If possible, relocate your living or working spaces further away from the source of the Wi-Fi signals.
- “Natural” Barriers: Thick bushes, trees, and other natural barriers can attenuate Wi-Fi signals to some extent.
- Thick Walls and Ceilings: Increasing the thickness of the walls and ceilings can reduce the Wi-Fi signal penetration.
- Use of Dense Materials: Incorporating dense materials like bricks or concrete in the building structure can potentially block Wi-Fi signals.