Why Are There Mice in my House?

Rodents will climb ladders, scale walls, walk across wires and swim through sewers (yes, they can come up through your toilet!) to get inside your home. So, how can you keep them out?

The truth is mice are adaptable and they are relentless in their search for food, warmth and shelter and your home can support all of their basic needs. In the fall and winter, these needs become more acute, hence their desire to get inside.

Do not underestimate mice 

Mice are opportunists and determined. They will seek out any defect in your home to gain access.

It is for this reason you have to become a DIY King (albeit temporarily) to plug every hole, seal every gap, repair any and all damaged parts of your property.

How mice get into your home 

When talking about rodents, an expert once stated, “You have to admire their agility.”

That’s nice to think about, but when you have mice in the attic it’s the last thing you really want to admire…usually the first thought is to panic! However, it is important to be aware of their agility. You should also note that young mice can fit through gaps as small as the width of a pencil (6mm)!



What all this means is that you shouldn’t just look for obvious entry points into your home. How about remembering to check gaps around pipes too?

Did you know?…..

  • Mice can readily scale 2 meter high walls
  • Mice can squeeze through holes the width of a pencil
  • Mice can jump as high as 24cm
  • Rats are able to jump 77cm vertically and 120cm horizontally

Via your roof! 

It is not a coincidence that another name for the Black Rat is Roof Rat. Black rats in particular are even more agile than other species and often find ways indoors via roof tops. Roof rats will traverse utility poles, cables, plants and shrubbery growing up the side of your house to find a way inside.

Are you still wondering how mice got into your cupboards? Well, picture the back of your fridge/freezer. To you and me, it is a necessary part of the appliance, but to rodents it is a veritable climbing frame. It allows them access to leftovers and food located high on kitchen counter surfaces.

Other common entry points into your home:

  • Via gaps in basement
  • Unplugged holes around old or new piping
  • Via structural defects – damaged flooring or roofing
  • Via air vents
  • Via drain pipes – yes, rats can swim pretty well and survive in sewers and drains

How to Keep Mice Out

As a homeowner, it is in your interests of health, safety and money to prevent mice and rats.

Mice and rats breed very quickly turning a small problem into a large scale infestation. Combined with the known diseases rodents can carry and the damage they can do to wiring, cables, furniture and other parts of your property, it pays to take action early.  

As with anything, prevention is always better than cure.

There are many steps you can take to prevent mice now, which are both low effort and low cost. To reduce risks further, professional prevention solutions are also available.

Prevention Tips

  • Food storage- food should be stored in plastic or metal containers. Regularly clean under stoves, refrigerators and cupboards.
  • Doors – Fit bristle (or brush) strips to the bottom of doors to prevent entry, especially in older properties where the door fit may not be snug.
  • Pipes – Seal holes around existing or new pipes with coarse grade stainless steel wire wool and caulking.
  • Holes – These are often made in exterior walls for cables and pipes; check that old pipe holes are sealed too. Any holes that are larger than 5mm will allow mice to gain access because their jaws can fit into tight spaces like these and quickly gnaw larger openings that allow them to enter a building.
  • Vents – Cover these with fine galvanized wire mesh, especially if they are damaged.
  • Eaves – Fix damaged roofing and use wire mesh to seal gaps.

Find more prevention tips here!

What Mice Do In Your Home

What attracts mice? Mice require 3 main things to thrive: shelter, warmth and food. Your home provides all these things, as it is essentially what we humans also need.

Find Shelter & Build Nest

Once inside, mice will quickly search for an isolated spot in your home, but ideally one that is close to a food source, such as your kitchen or dining area. This is why you often find mice nests behind kitchen appliances and at the back of your refrigerator. It’s also quite warm there as well.

Mice love paper to build their nest. Anything from newspapers, to magazines that you might be hoarding in an unknown corner of your house, or even toilet paper or paper towels in business premises will suit their nesting needs.

Search for Warmth

Mice can easily find warmth by locating a nest inside your cavity walls, under your floorboards or near to your hot water tank or even up in your attic.

Find Food 



What do mice eat? Most people know that its cheese but chocolates and even peanut butter will appeal to mice. They have even been observed with a particular preference for a certain flavor of potato chips.

Mice are able to get their daily water requirement from the food they eat – as long as it contains certain levels of moisture. Rats, on the other hand, do require access to free water and cannot survive on moisture from food alone. It does explain why rats love bread and vegetables like potatoes, which have high water content and their general fondness for a trash bin.

This explains why mouse problems are more common in homes than rats. Having said this though, if you live near a river, lake, stream or happen to have a neighbor with a rather large fish pond in the back garden (like me!) you are just as likely to be at risk of rats!

FACT: Did you know…mice will feed from multiple places in any one night, but rats are more cautious, preferring to stick to 2 or 3 different places only.

Nighttime Activities

Mice are nocturnal, so it is rare to catch sight of them during the day, unless you have a very big infestation problem. Signs of mice can be found any time of day, if you are looking for it.

Using base boards 

Their natural instincts dictate that they move about their environment with caution and always along the edge of something. It would be rare to see mice darting across an open floor. In your home this is usually along baseboards or kitchen cupboards. In the wild, this behavior protects them from predators.

FACT: Did you know…whatever activity they are doing, a rodent’s eye will always be looking upwards to stay alert for any predators.

If a mouse problem is left unmanaged, you will begin to see smear marks appear along their common route, which is created from the repeated rubbing of their greasy fur along any form of edging.

Bodily functions

Another obvious sign of their presence in your home is evidence of urine and mouse droppings. Rodents will go out of their way to urinate on things. It’s a form of marking their territory and also communication with other members in the group – directing them to available food sources.

Ever heard of urine pillars? In the case of heavy and long term unmanaged infestations, the continued urination from rodents on the same spot will eventually lead to a build-up of material called a urine pillar.

Urine pillars are essentially vertical towers of pee combined with the grease from their fur.

Pillars can be found on kinks in the ground or anything that sticks out – like the bottom half of a screw for example.

Within a mischief of mice or rats (yes, that is the official term for a group), they can also tell from the smell of the urine whether it was left by a male or female, the identity of the exact individual and even (if left by a female) if she is ready to mate!

You could also find up to 80 small mouse droppings following one nighttime excursion in your kitchen!

What should you do now?

In the wild, mice can survive for 1 year to 18 months given the right social and environmental factors, and all the time multiplying in numbers.

Can you see now how your house could quickly be overrun if no action is taken to prevent an infestation?

Follow the #RodentRebels for more information and tips on prevention and control of rats and mice.


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