Materials that Block WiFi Signal (and What to Do About It)

What's Slowing Down Your WiFi?

We love WiFi. That is, until it stops working in a certain room, during meetings, or when we're streaming. Weak or spotty connection isn’t just annoying, it can impact work and even home security. While we’re quick to blame internet providers most of the time, the culprit can actually be your surroundings and the materials they’re made of.

We’ll help you get to the root of what’s interfering with your connection and what you can do to fix it, whether you’re dealing with poor WiFi reception in a single room or throughout your house.

Everyday Materials that Block WiFi Signal

Metal

Metal is one of the worst offenders. It reflects electromagnetic waves, making it nearly impossible for WiFi signals to pass through. This includes metal doors, filing cabinets, ductwork, and even foil-lined insulation. If your router is placed near or behind metal surfaces, you’ll likely experience slow speeds or dropped connections.

Concrete Walls

WiFi signal does not mix well with concrete as it’s one of the thickest building materials. Basements and multi-level homes often suffer from low signal strength because of these dense structures. The heavier the wall, the harder it is for WiFi to make it through.

Plaster & Metal Lath

Many modern structures use metal laths in plaster to act as a framework for interior walls. Since metal lath consists of metal and takes part in creating thicker walls, the WiFi signal can be greatly reduced or blocked.

Ceramic Tiles

Found mostly in kitchens and bathrooms, ceramic tiles can block signals, especially when layered over drywall, concrete, or wood. Try raising your router off the floor or moving it to a tile-free area to improve coverage.

Windows and Tinted Glass

We know what you’re thinking… “How can windows and glass affect my WiFi signal?” They are transparent and not as thick as walls. But, don’t let their look deceive you.

Standard glass has little impact on signal strength, but Low-E (low emissivity) glass or windows with metallic tint reflect WiFi signals. If your home has large panes of tinted glass, it could be contributing to your weak reception.

Mirrors

Mirrors contain a thin metallic backing to create reflection, and unfortunately, that same layer bounces back WiFi signals. Large or strategically placed mirrors between your device and router can disrupt your connection. Small-to-medium wall-hanging or decorative mirrors are less likely to have such an impact, so no need to worry there.

Drywall

Drywall has a small impact on WiFi, but the problem adds up if you need the signal to pass through multiple walls. For apartments or homes with many rooms, drywall can be a slow drain on signal strength. For ample coverage across larger homes, it’s best to invest in a signal booster or set up additional WiFi touchpoints.

Furniture

Large furniture made from dense wood or metal can absorb or block signals. We know how much you want to tuck your router away some place out of sight. With that said, if your router is inside a cabinet or behind a couch or bookshelf, it’s worth repositioning to a clearer area if you notice signal issues.

Other WiFi Blockers

If you've gone through the usual suspects and your WiFi issues persist, the cause might be something less obvious. One of these less common but still very real interference sources could be what’s holding your connection back.

Devices Operating on the 2.4 GHz Frequency

Microwaves, cordless phones, Bluetooth speakers, and baby monitors all share space on the crowded 2.4 GHz frequency band. Since they’re constantly competing for bandwidth, this can cause WiFi slowdowns, lag, or even dropped connections. While modern WiFi standards are designed to manage and reduce signal interference between compatible devices, many of these household items don’t actually connect to your network; they just disrupt it. Without that communication protocol, they end up contributing to signal congestion, which weakens performance across your entire network.

Neighbor’s WiFi Network

If you open your settings and look at the available wireless networks, how many different network names can you see? The answer is typically, “A lot”.

Your neighbors' WiFi just might be fighting for the same channel. Overlapping signals on identical frequencies can degrade your internet performance. Switching to a less congested channel or using the 5 GHz band can help.

Water

Believe it or not, water is a strong signal absorber. That fish tank or indoor water feature in your space could be quietly weakening your connection. You may need to reposition the router away from the main water feature, similar to how you would act if it was a large mirror or a cabinet.

Appliances

Fridges, ovens, and washing machines aren’t just bulky, they often emit electrical noise and are made from metal. Although uncommon, both factors can contribute to WiFi disruption if your router is placed nearby.

How to Improve Your WiFi Signal

1) Move Your Router

Your router’s location matters more than you think. Place it in a central, elevated spot with minimal obstructions. Avoid corners, enclosed cabinets, or placing it next to large electronics or metal objects. Open space equals better signal distribution.

2) Upgrade Your Router

Older routers simply aren’t optimized for modern usage. If you’re still using a router from 10+ years ago, consider upgrading. Newer models offer better range, faster speeds, and smarter handling of multiple devices.

3) Upgrade Your Router’s Antennas

Not all routers allow this, but if yours does, upgrading to high-gain antennas can help. These provide a wider signal reach and help eliminate dead zones in larger or multi-story homes. The improved signal pattern can also help navigate around obstacles.

4) Get a Mesh Network

Mesh networks significantly improve WiFi coverage by using multiple mesh nodes, cutting out dead spots.

Our Top Picks:

5) Try a Range Extender

Range extenders, on the other hand, extend the reach of your WiFi router by creating a new, extended WiFi network for your devices to connect to.

Our Top Pick:

WiFi Blockers Cheat Sheet

For quick troubleshooting of signal issues in your home, keep our cheat sheet handy and tick off each item to find what’s blocking your WiFi connection.

WiFi Blocker	Effect on WiFi	Quick Fix
Metal	High signal loss	Move the router away from metal objects
Concrete Walls/Floors	Very high attenuation	Use a mesh system or reposition the router
Plaster with Metal Lath	Moderate to high loss	Add range extenders or nodes
Ceramic Tiles	Moderate signal loss	Raise the router, avoid tile-heavy rooms
Tinted/Low-E Glass	Reflects signals	Reposition the router away from windows
Mirrors	Reflects signals	Avoid placing the router behind mirrors
Drywall	Minor interference	Optimize router location to a central area
Water (Aquariums, Other Water Features)	Absorbs WiFi	Keep routers away from water sources
Appliances	Channel conflict	Change your WiFi channel
2.4 GHz Devices	Frequency interference	Switch to the 5 GHz or 6 GHz band

FAQs

How Far Should WiFi Reach?

Here’s the average indoor and outdoor range for common WiFi frequencies:

Frequency	Indoor Range	Outdoor Range
2.4 GHz	Up to 150 ft	Up to 300 ft
5 GHz	Up to 100 ft	Up to 200 ft
6 GHz	Up to 50 ft	Up to 100–150 ft

How Can I Measure My WiFi Signal Strength?

The WiFi logo on your devices illustrates the strength of your WiFi signal, but it doesn't give you the strength measurement. Knowing the strength measurement can show you how much your signal is affected by certain obstacles.

There are many different ways to measure WiFi strength. Using dBm (decibel-milliwatts) measurements is the least complicated and most common method.

dBm for WiFi is expressed in negative numbers; the signal strength can range from -30 to -90 dBm.

• -30 dBm: Represents the best WiFi signal possible. It's usually achieved by standing next to the WiFi router.
• -50 dBm: Anything within this range will experience an excellent signal.
• -60 dBm: Reliable signal strength.
• -70 dBm: Not a strong signal.
• -80 dBm: Unreliable signal strength.
• -90 dBm: A wireless connection is near impossible.

The closer you are to -30 dBm, the better and stronger the signal will be.

To measure your WiFi signal strength on your cell phone, tablet, or any wireless device, you can use the WiFi Analyzer App for Android or Apple. The apps are extremely easy to use. You can conduct multiple tests in different rooms and see which building materials have the greatest impact on your WiFi performance.

Does WiFi Go Through Walls?

Yes, but performance depends on the material. Drywall can be mostly fine, but concrete or brick not so much. The thicker the walls between your router and device, the weaker the signal becomes.

Does Lead Paint Block WiFi?

Lead paint, while rare today, can block signals due to its metallic content. If your home still has it, it could reduce WiFi strength, but it's unlikely to be the main issue unless layered heavily.

Get Better Signal, No Matter What’s in the Way

Now that you know what’s blocking your WiFi, it’s easier to take the right steps. From metal surfaces to competing frequencies, your environment plays a huge role in your connection quality.

Need help putting all the pieces together? Contact the experts at SignalBoosters.com. We can help recommend the best signal booster for your space. Call us at 1‑800‑470‑6777 or reach out to sales@signalboosters.com.

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