Signal Booster Building Materials Block Cellular
List of Materials and How Much They Block Cellular Signal:

Reasons why cell phone signal booster coverage varies within different homes and buildings

Mother Nature and Rain

While Mother Nature does block cell signal from -5 to -25 dB where rain attenuates signal anywhere from -1dB to -5dB and foliage attenuates it anywhere from -1dB to -25dB, the odds are that it is your home building materials that blocks most of your signals. They are the number one cause of cell phone reception disruption.

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, 4G, 5G 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. Although porous, fiberglass insulation in walls and attic can disrupt cell phone signals slightly, if it is thick enough. Foil-faced design of some insulation products helps keep out unwanted elements. However, foil facing used on insulation products like foam board or fiberglass batts can block radio frequency signals. Additionally, the interior walls made with denser materials can cut the reception down another -2db. In this manner, sheetrock and insulation has the potential to cut your cell phone reception before it even enters your home.

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. Reduction is even higher at -9dB on 5G network. 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 decibels (dB) detected by your phone is how the signal strength is measured most accurately. This is true whether your phone is using 2G, 3G, 4G LTE, or 5G. A good signal strength metric is RSSI - Received Signal Strength Indicator. RSSI is a negative value, and the closer to 0, the stronger the signal. In other words, the closer to -50db you are, the better the signal because it typically ranges from -50 (strongest) to -120 (weakest). 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.