And why DIY solutions almost always let rats and mice back in
When it comes to stopping rats and mice from re-entering properties, most failures happen for one simple reason: the wrong materials are being used. Many commonly recommended DIY products give people a false sense of security, but from a scientific and behavioural standpoint, they are completely inadequate against a motivated rodent.
Rodent proofing is not about guesswork or temporary deterrents. It’s about understanding the animal, its physical capabilities, and using materials engineered to exceed them.
Let’s break down the most commonly used products—and why they fail.
Steel Wool / “Wire Wool” – The Biggest Myth in Rodent Proofing
Steel wool is one of the most widely used materials for blocking holes, yet it is fundamentally flawed.
Why people think it works:
- It’s made of steel
- It feels abrasive
- It looks difficult to pass through
Why it actually fails:
Steel wool is not designed for pest proofing. It is manufactured for polishing metal and cleaning pipework. The density is completely wrong. For steel or mesh to be effective, it must:
- Have an EN rating
- Be denser than the width of a rat’s incisors
A rat’s front teeth are incredibly strong and constantly growing. If the material density is lower than the tooth width, the rat can either:
- Push it out
- Compress it
- Or simply chew through it
Steel wool is also:
- Flammable
- Soft when dry
- Frequently found inside rat nests, where it actually provides insulation
In short, steel wool does not stop rodents—it often helps them. By contrast, the materials we use are:
- Perforated, non-combustible metal
- Correctly density-rated
- Installed using glass fibre reinforcement
- Fixed with silicone for mice or cement for rats
This is what allows us to provide a long-term guarantee.
Expanding Foam – A Rat’s Dream Material
Expanding foam is another commonly used “solution” that fails consistently. If you have a company using expanding foam, ask them their guarantee period, is it 12 Months!? The reality is if a human can push their finger through it, a rat can tunnel through it with ease.
Once cured, expanding foam:
- Is soft and friable
- Does not bond structurally
- Rarely fills voids correctly
- Creates perfect internal tunnels
Rats and mice simply excavate it, much like digging through polystyrene or marshmallow. It offers no resistance whatsoever to a professional burrower.
Expanding foam is a hole filler, not a pest-proofing material.
Sonic and Ultrasonic Devices – Proven to Fail
Plug-in sonic deterrents are heavily marketed and widely purchased—but they simply do not work.
- Rodents habituate to sound
- The noise becomes background interference
- Within a short time, it is ignored completely
There are countless real-world examples online of rats and mice living comfortably next to these devices. We would never recommend them, and they offer zero long-term protection.
Rat Traps – Ineffective and Often Inhumane
Rats are neophobic—they fear new objects in their environment.
This means:
- They often avoid traps for up to 20 days
- Human scent marks you as a predator
- Many rats actively bypass traps altogether
There is also extensive footage showing rats:
Triggering traps with sticks
Taking bait without being caught
Or sustaining severe injuries without dying
This can lead to prolonged suffering, which we fundamentally oppose. Traps may occasionally catch rodents, but they are unreliable, ethically questionable, and do nothing to address entry points.
Peppermint Oil, Smells, and Bleach – Short-Term at Best
No smell or oil can deter a rat long term.
- Oils evaporate
- Scents dissipate
- Rats adapt extremely quickly
Some bleach-based cleaners can discourage rodents briefly, while wet, but once dry, the effect is gone. These products may help with cleaning and hygiene, but they are not prevention tools.
The Only Effective Solution: Understanding the Enemy. Stopping rats is not about gimmicks. It is about:
- Understanding rat behaviour
- Knowing their motivation
- Identifying entry routes
- Using materials engineered to exceed their physical abilities
At Pest Proof London, we use:
- Handheld inspection cameras to track voids and entry paths
- Density-rated, fireproof, perforated materials
- Glass fibre reinforcement
- Correct fixing methods based on species
This systematic, science-led approach allows us to solve complex rodent infestations, not just temporarily delay them.
Why DIY Methods Always Fail
Rats are:
- Highly intelligent
- Exceptionally adaptable
- Extremely motivated
Temporary measures do not stop them—they only postpone the inevitable. This is precisely why Pest Proof London is one of the only companies in England offering a one-year guarantee on rodent proofing. We rely on proven materials, specialist equipment, and trained professionals.