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How Much & Which Building Materials Block Cellular & WiFi Signals?

Oct 10, 2017

How Much & Which Building Materials Block Cellular & WiFi Signals?

Have you ever wondered how much do various kinds of building materials block cell phone and Wi-Fi signals? Well, here's your chance to find out! If you have reception problem with your cell phone, you may find that you're a bit frustrated with trying to determine the cause of your weak signal. Your phone works in some spots outside of your home, but inside your abode, there is little to no signal at all. Obviously, there's something in the house which is stopping the reception, but what is it? The odds are that it is your home building materials. They are the number one cause of cell phone reception disruption. Knowing which materials can deflect your cell phone reception may help you to find solutions to increase or gain your signal using a cell phone signal booster or similar device. Or even help you "reduce reception" if you're concerned about radiation affecting your health. Either way, here're the top building materials that stop wifi and cell phone signals in its tracks.

Clear Glass.

There's a misconception that clear glass fixtures, such as windows, are the best place to gain access to a signal. While the clear area is ideal for letting in light, they can bounce a signal around or reflect the signal away from the house. This is especially true for windows which are double insulated. There're triple pane windows in newer homes with reflect signals even more. The most deflecting ones are the latest low emission (Low-E) windows that keep the elements out to keep you warm or cool inside depending upon the weather outside. But if you're looking to improve cellular reception by standing next to a window, open that window for most impact. Blockage on windows can reach -4db.

Sheetrock and insulation.

Sheetrock is one of the lower blocking agents for a cell phone signal. However, it can cause your signal to be blocked completely if it is already weak. Keep in mind that 3G and 4G signals are generally the same as a radio signal and so you can see fluctuations in your signal of -2db. Closed rooms, meaning those which are not a part of an open floor plan, are more susceptible to cell phone signal disruption than sheet rocked rooms which are part of an open layout.

Insulation, due to the thickness and its design of keeping out unwanted elements, can disrupt cell phone signals. Spray foam insulation is the most damaging to a signal, but all insulation has the potential to cut your cell phone reception in half before it even enters your home. Additionally, the interior walls can cut the reception down another -2db.

Plywood and Solid wood.

Plywood which makes the majority of the structure and framework for many residential homes, reduces 3 and 4G networks up to -6db. This number fluctuates a bit as there're different thicknesses of plywood, and different ways in which the plywood is compressed. Additionally, the cell phone reception loss can be increased should the plywood get damp/wet with numbers as low as  -20db. But if the plywood on your house is wet, you have bigger issues to worry about(!)

Solid wood, such as that used in the flooring of the house builds upon the blocked signal of the plywood. While the finishing on the doors, floors, decking, etc. may be nice for that natural look, they are cell phone signal blockers. All wood slows down a signal. The thicker the wood, the more it will disrupt cell phone signal strength. Softer woods, such as pine, may not decrease the strength much, but you could still see a loss of -5 to -12db.


Though incredibly sturdy against the elements, brick is one of the top materials for blocking a signal. First you have the thickness of the brick which slows the signal down. Secondly, you have mortar between the bricks which does not allow a signal. Additionally, brick generally has supplementary materials on the interior so that electronics, sheetrock, shelves, etc. can be added. The mere thickness of the wall combined with the density of this building material can block up to a whopping -28db scale.


When it comes to building materials, Metal is the top cell phone signal disrupter. Metal roofs as well as metal studs and interior metal will slow down the signal. While metal looks nice on a building, is durable against the elements, and can help with routing electricity and such away from the walls underneath, it can also route the signal away from the house. Most houses which have metal roofs will find that even if they live in an area where exterior signals are strong, interior signal strength will be weak if not non-existent. Ratings can drop as low as -32 to -50db, essentially making your home a dead zone.

Why should I care about the db and how can I increase my signal strength?

The DB on your phone is how the signal strength is measured. The closer to -50db you are, the better the signal. Keep in mind that a -120db is a deadzone while -50 is full bars. This is not to say that metal will put your phone at -120db though (dead zone). It may put it at -100db or more. The closer to -50 dB, the better the cell reception.

To increase your signal in hour home, use a residential cell phone signal booster. Follow the steps in other articles on finding the best spot for your cell phone signal booster. Should you have questions about which booster is best for your home, business, or commercial space, please let us know as we would be happy to help you find the right cell phone signal booster.

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  • It looks like there aren’t many materials that help with signals. This pretty much measures up to what I’ve seen wherever I go. I’ve been in condos, townhouses, beachhouses, and homes, and there are always problems with cell coverage. I gotta say it is cool to know how to boost cell phone signal strength using these cell phone signal booster doo-dads.

    C.C. Tompkins on
  • I love this site. I learn so much about cell phone technology by browsing the various articles. I always thought a window was a surefire way to get a good signal while inside. Apparently not. It’s amazing how poor cell phone reception can be inside your home, even when you have a decent cell phone.

    Michael Rickard on

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