How DID The Rats Get In The Cavity Walls

Rodent Guide
Written By Rodent Guide

I believe in treating all creatures with respect. My mission is to ensure everyone understands how to protect their home from rodents without using cruel methods.

There are two things you need to know about rats;

1. They only need a tiny hole to gain access to your property, and

2. Rats can chew through almost anything to get there!

Now you are hearing scratching inside your walls. It might be rats! But how DID the rats get into the cavity walls?

How DID The Rats Get In The Cavity Walls

What is a cavity wall?

A cavity is a gap between the two skins of brickwork. The gap ensures water is not transferred from outside the house to inside.

The outer layer of bricks absorbs the water, and as it passes through,  the water drops to the ground and not into the house.

How Rats Get in the Cavity Wall – 5 Common Ways

5 Ways A Rat Can Get Into Your Cavity Walls Infographic

1. Roof Edges

How DID The Rats Get In The Cavity Walls roof

This is a widespread way for rats to get into your cavity walls, especially if you have overhanging trees next to your property.

Rats can easily climb trees, and as soon as they enter your home, they will look for a weakness to exploit to gain entry.

The joint between your roof and walls is likely to have big gaps to fit a rat in. There is good news. It is easy to avoid this by ensuring no hanging trees on your property and ensuring there are no other ways a rat can access the top of your house.

2. Venting Systems

How DID The Rats Get In The Cavity Walls venting

Venting systems will pass through the brickwork of your home, and if they are not installed correctly, they could leave gaps that rats can easily use.

You will need to check the venting system for any potential flaws in the installation. If you find any, it is an excellent idea to close them. It will help stop rats from getting into your cavity walls and help keep your home warm in the winter!

3. Weakness in Masonry

How DID The Rats Get In The Cavity Walls weak points

Over time, the mortar between bricks becomes weak and will crumble away.

Gaps between bricks offer a rat the opportunity to enter your house and set up a home in your cavity wall.

You must regularly assess your home for weak mortar and call in an expert to re-point to ensure any rats cannot get in.

4. Air Conditioning

How DID The Rats Get In The Cavity Walls air conditioning

Air conditioning units need to pass through your walls to the outside, allowing a rat to find a weakness to exploit.

Pipes and cables need to be passed through to the outer layer of your property, and the installation may have left small gaps that can easily fit a rat into. It is time to get the ladder out and check for gaps to plug!

5. Cable Holes

How DID The Rats Get In The Cavity Walls cable

Many homes have cable or satellite television. For the cables to reach the inside of the house, there must be a hole to pass the cables.

Rats only need a very small hole to enter your building and cable holes are certainly big enough.

If a rat uses this route into your house, you will likely get some warning signs, especially as they would have chewed through the cable! For example, an early warning sign would be an inconsistent television signal or maybe no signal.

Check your cables for signs of chewing.

The reason why you do not want rats in your cavity walls

There is one excellent reason you do not want rats in the cavity walls, and it is the same reason you should not use rat poison! When a rat dies in your cavity wall, it will decompose.

Unfortunately, I have had a decomposing rat in my attic. I only realized this when the odor from the dead rat began to drift down into the rooms on the 1st floor.

Finding the rat was very easy, it was a simple case of following my nose in the attic. Find a dead rat in your cavity walls is going to be a much more difficult task.

You will no doubt need to enlist the help of a professional.

How to Get Rid Of Rats in the Walls

If you have noticed rats in your cavity walls, then I am certain you will need to know how to get rid of them.

You have three options:

  1. Damage the wall – this should be the last resort because it will cost you a lot of money to fix!
  2. Tempt the rat out – tempting the rat out of a hiding place is relatively easy. It just takes time and patience. You should set some humane traps with some rat bait near any entry point to the wall. The rat will smell the bait and eventually find it, getting trapped. For a rat to be tempted to leave the security of the cavity wall, you cannot be in the vicinity of the wall. The rat will sense that you are there and will not come out. I suggest you set up the traps and leave home for a few hours.
  3. Wait for the rat to leave the walls – This is similar to the option above and involves setting up a trap. The only difference is that you set the trap up and go about your daily business. Rats do not stay in the walls permanently. Instead, they have to venture out to find food and water. When they venture out of your cavity walls, they should be tempted by a trap you have set up nearby. This is likely to happen after sundown when you are asleep, so check in the morning.


There are many ways that a Rat can get into the cavity walls. The 5 above are the most common.

The important thing is that you regularly carry out maintenance on your property to limit a rat being able to gain access in the first place.

Every few months, you should perform a routine check outside your home. Check for holes, weak points, and anything that needs to pass from inside your house to outside. Look at the cabling and look for pipework. Record all rat entry points and make a checklist that you can use for each check.

The last thing you want is a rat dying inside a cavity wall!

Good luck.


About the Rodent Guide

I’m an expert in do-it-yourself rodent control. For more than 20 years, I’ve dedicated my life to helping people live harmoniously alongside these critters by sharing rodent control solutions that are effective and kind.

I believe in treating all creatures with respect. My mission is to ensure everyone understands how to protect their home from rodents without using cruel methods.

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