Via the drains

Houses are warm and dry and sewers are full of food, ideal for rats


Rats are in the sewers and the rat population likes to nest and rest within houses

The bit that connects houses to sewers are the drains – and this is where the vast majority of the rat entry into houses arise.

Most rat in house scenarios arise from the following:

Rats get into a house via an uncapped inlet

Rats can get into your house when something like a downstairs toilet, stack pipe or gulley is moved but the associated pipework underground is left uncapped.  Although the pipework is now redundant, it’s still connected to a sewer and therefore rats can travel up it and use the uncapped enter to transfer across to the building fabric.

Rats get into a house via cracked clay pipe

Older properties used clay pipes to transfer the waste under the footprint of the house of along the back or side of it in close proximity to the footings.  These clay pipes can crack, collapse or have sections come apart allowing rats to emerge under the suspended timber floors’.

Rats get into a house via plastic to
clay pipe joins

Clay pipes have different wall thicknesses to modern PVC pipes. A rubber flexible coupling is typically used to join the two pipes together, but rats can gnaw through these like butter and they’ll often come apart during slab settlement. Just another way for rats to get into your house.

Rats get into a house through chewed plastic pipes

Modern plastic pipes are made from PVC and are around 4mm thick. Providing rats can access a leading edge, the rats can gnaw through the pipes very easily and the rats can enter your house.

Rats get into a house via soil vent pipes

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Rats enter a house via guttering downpipes

Because gutter pipes are so narrow (68mm), rats don’t need to grip the smooth insides, they simply push themselves against the inside of the pipe and wriggle up in a similar undulating movement to a snake. This means rats can access soffit runs and enter your house via your roof space.


Surface rat activity entering an above ground defect

Surface rat activity can develop where food is available through bird tables, dog and cat food left outside, compost heaps, uncontained refuse etc.

If an opportunity presents itself for rats to get into a house the rats will enter for the same reasons sewer rats do – it’s drier and warmer than outside

Most common rats in house scenarios are as follows:

Rats enter a house via damaged or missing air bricks


Air bricks can be cast iron, ceramic or plastic and are there to ventilate wall cavities and floor cavities and so keep damp issues at bay. Plastic air bricks are the highest risk as rats can gnaw through these to pass in and out of the wall cavity or suspended floor void.

Rats get into a house via pipe passage points


Water pipes often pass through walls to service outside taps or carry waste water to outside gulleys. If the walls are cavity walls and the gap around the pipe is more than 10mm, this could be a potential entry point for rats to get into the house or building fabric.

Rats enter a house via gas or electrical intake points

Modern buildings have external gas and electrical meters that pass a feed into the house or building via a hole in the wall. Again, where cavity walls exist and the gap around the feed is more than 10mm, then this could be a potential entry point for the rats into the house.

Rats get into a house under rear or side door thresholds

A common problem for extensions and for uPVC doors in particular is often a gap between the brickwork and step as the builder will always make a doorway larger than the door to make fitment easier. This is yet another way for rats to get into your house.

the rats NUMBER 3 ROUTE:

Via a neighbouring property

Most houses will be within a terraced row or block of flats – semi-detached at best.

Depending on the construction of the building, sometimes rats can travel across from one building to another via wall cavities and roof voids or via shared service ducts for blocks of flats.

This is typically a consideration with terraced and semi-detached houses built from 1930 onwards as that’s when cavity walls began to become mainstream and roof voids simply had an internal firebreak rather than a continuation of the party wall through the roofline as with Victorian and Edwardian buildings. This provides a very convenient route for rats to get into your house.

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