How to Get Rid of Rats Under Floors for Good
A real Owl Pest Control drain survey and repair case study (Dublin)
If you are hearing scratching, scurrying or gnawing noises and you suspect rats under floor, behind your kitchen units, or up in the attic, you are not alone. At Owl Pest Control, we regularly get calls from homeowners who have already tried traps, bait, blocked a few obvious gaps, and even had “a rat job done” before, only for the problem to come right back a few weeks later.
This case study is about one of those jobs: a persistent rats under floor issue in a kitchen extension that only stopped once the drain defect was repaired. It started with persistent rat noises under the floor in a kitchen extension and ended with a permanent fix, once we followed the evidence to where the rats were really coming from: the drains.
If you are trying to get rid of rats in ceilings, attics, walls or under floors and nothing seems to work long-term, read on. You’ll find out how to identify issues, why drains are often to blame, and what a thorough drain inspection and repair entails.
The problem most people miss: rats do not “live in the attic”
Let me start with a simple truth from the field: rats rarely choose an attic as their “home base” unless something is giving them safe access, warmth and a route in and out. More often, the attic (or the cavity wall, or the void under the floor) is part of a travel network.
And that network very often starts underground…
On our drain service page we mention it plainly: sewer pipe defects are a leading cause of rodent infestations, because broken pipes and openings become entry points straight into a building’s structure. We see again and again: when a rat infestation keeps reoccurring, a “surface level” approach will not solve it. If there is a drain defect, you can catch rats all day long and new ones will keep appearing.
Quick checklist: Common signs of rats under floors, in ceilings or in walls
How do we know it is rats and not mice, pipes, or just the house settling? Here are the most common indicators that push a job into “likely rats” territory:
- Noises at night: scratching, scuttling, gnawing, often the classic sound of rats under floor voids, and sometimes a thud as they drop inside a cavity
- Bad smells: a stale ammonia odour from urine, or a stronger smell if something has died in a void
- Recurring activity after baiting: it improves for a week or two, then returns
- No obvious external entry point at ground level (no gap, no broken air vent, no open door threshold)
- Drain-related symptoms: foul odours, slow drainage, recurring blockages, odd gurgling noises from pipework
When we hear “noises under the kitchen floor” plus “nothing obvious outside” plus “it keeps coming back”, our mind goes straight to the drains.
Why drains are so often the real source of the rat problem
Rats are excellent climbers and diggers, but their favourite motorway through an urban area is the sewer system. They are protected, they have water & food, and they can travel unseen. If there is a defect in the private drain run, an inspection chamber, or a damaged manhole cover, they can leave the pipe and enter the surrounding ground or structure.
Where drain pipes pass through walls, there is often a flexible gap by design. If rats escape the pipe close to the building, that gap can become the gateway into cavity walls and floor voids, and from there into ceilings and attics:
On modern builds and extensions, insulation materials and enclosed voids can make it even easier for rats to move around unseen once they are in.
Who is responsible for underground drains (and why this causes confusion)
One of the reasons these cases drag on is that homeowners are not always sure who is responsible for what.
Uisce Éireann (formerly Irish Water) have responsibility for issues and blockages on the public sewer network, while householders or property owners are responsible for internal plumbing and the private-side pipework leading up to the sewer mains. They also publish a pipe maintenance responsibility guide showing how responsibility typically sits around the property boundary.
Dublin City Council similarly notes that householders are responsible for blockages in private drains.
In real life, the tricky part is that a quick check of “the main line” does not prove that your own private drains are sound. And if the defect is under an extension, buried beneath a floor, or hidden behind a perished frame, it will not be spotted without the right inspection.
Case study: months of rat noises under the kitchen floor (Dublin)
The call
We were contacted by a homeowner who had been hearing rat noises for months under the kitchen units, in a house extension. They had tried pest control measures already, but every time things settled down for a short period, the noises came back:
Importantly, there was no obvious rat entry point at ground level. No broken vent cover. No obvious hole at the exterior. No clear route.
That is exactly the point where you stop repeating the same tactics and start investigating the hidden system.
Our initial suspicion
Because there was no clear external entry point, we immediately suspected the rats were accessing the building from a sewer or drain defect somewhere under the floors. This is why our drainage division exists. On our drain service page we set out what we do: CCTV drain surveys to identify cracks, leaks, blockages or collapsed sections, and smoke testing where needed to reveal concealed breaks and entry points.
Step 1: clear the line properly (jetting) so the survey is meaningful
A lot of people are surprised by this: you can put a camera down a drain, but if the pipe is partially blocked, the footage can be impeded and misleading. In this case, we jet washed the sewer system, which was blocked in some parts, before carrying out a proper investigation.
We also do this routinely as part of drain cleaning and maintenance, because build-up and blockages create both hygiene problems and pest harbourage inside pipework.
Step 2: CCTV drain survey and mapping the network
Once the system was cleared, we carried out a more extensive investigation and mapped the drainage layout. A proper CCTV survey is not just a quick look down one straight run. It is about understanding the branches, junctions and access points so nothing gets missed.
CCTV drain surveys are an asset to identify issues quickly, saving time and reducing disruption. Typical surveys often take around one to two hours, depending on the length and complexity of the system.
In this case, the mapping led us to the real “aha” moment.
The discovery: a broken manhole buried under the kitchen floor
After investigating the sewer system, we identified a broken manhole buried under the kitchen floor (marked “BMH”, in yellow on our plan):
This is more common than you might think, particularly with older properties that have been extended over time. A manhole that used to be outside becomes enclosed by an extension. It gets tiled over. It is forgotten. Then years later, the frame perishes, or the cover shifts, or a connection fails.
In this case, the buried manhole had a rusty and perished cover frame, which was effectively giving rats access directly into the void beneath the kitchen floor.
So the rats were not “magically appearing”. They were doing what rats do: exploiting a hidden, protected access route.
Step 3: agreeing the repair plan (and being honest about disruption)
Here is the part that matters for trust: permanent fixes sometimes require intrusive work, and we always explain that upfront. We proposed to cut and remove a section of the wooden floor and tiles to expose and fix the issue properly. We also advised the customer that for intrusive repair jobs, the floor or walls cannot be reinstated to their original condition.
That conversation is essential. The last thing anyone wants is a surprise when tiles need lifting. Once our customer agreed that it was the best option, we moved to repairs.
Step 4: the repair itself (what we actually fixed)
From a pest control point of view, the critical piece is that the infestation problem is eliminated: No entry point equals no rats under floor voids.
Why “standard” approaches often fail in these situations
Traps and rat bait are not a building repair
Traps and rodenticides have their place, but they are not a substitute for fixing entry points. If rats can still access the structure from the sewer network, you are merely “mopping the floor while the tap is running”.
The Failure of Standard Drain Surveys
- Knowledge Gaps: Many contractors fail because they don’t understand the difference between combined systems and separate foul/rainwater systems. There is also a myth that rats don’t use rainwater systems, but they will follow any pipe if a food source or entry point is available.
- “Straight-Line Surveys”: Standard push-rod cameras often miss “blind junctions” and offshoots, because they only travel in straight lines. A full survey must inspect every branch, not just the main runs.
- Camera Technology: Standard forward-facing cameras may not pick up all issues: Expensive pan-and-rotate cameras on another hand, may spot holes that are otherwise invisible around bends.
Poor Workmanship for Extensions is a repeat offender
Extensions and renovations are a major source of hidden rat problems. A major cause of rat under floor infestations is the improper capping of redundant pipes during extensions. This occurs when an outdoor gutter pipe or kitchen gully is now covered by the house extension.
Builders often “seal” abandoned pipes with empty cement bags, bricks, or slate, which rats can easily bypass.
In this very good example below, the drain camera followed a pipe going upward and captured an uncapped drain directly under the leg of a kitchen unit! (Survey/pictures credit: Davey Brown)
When we investigate persistent rat infestations, we are always thinking: what changed on this property in the last 10–20 years? A kitchen extension often sits right at the center of the story.
What to do if you are dealing with rats under floors, in walls or in an attic
If you suspect rats, here is the most practical, least-wasteful approach:
- Do not ignore the early signs: Noises, smells, droppings, or repeat sightings
- Avoid quick DIY sealing with foam. Rats can chew through poor materials. Proper proofing needs pest-resistant methods and materials.
- Ask the right question early “Could this be coming from the drains?” If the activity keeps returning, this question saves months.
- Get a professional assessment that covers both pest control and drains. A combined approach is where you stop guessing and start solving.
- If drains are suspected, request a CCTV drain survey (and smoke test if appropriate) These services are designed to identify cracks, leaks, blockages, or collapses and remove rat access points permanently.
Why using Owl Pest Control for drain surveys and rat-proof repairs?
Because we treat the cause, not just the symptoms. Our drain division uses CCTV inspection and smoke testing to uncover hidden issues, and we position this specifically as a way to prevent pest infestations by eliminating access points. We also set expectations clearly around time frames (often one to two hours for a survey) and we focus on long-term outcomes, not temporary relief.
If you are dealing with rats under floor activity (or rats in cavity walls, or rats in the attic) and it keeps coming back, there is a strong chance you are looking at a hidden drain defect or a compromised manhole.
Visit our main drain page to see exactly how we investigate and fix these issues:
Frequently Asked Questions
► Why do I keep hearing rats under floorboards at night?
Rats are most active after dark. If you hear regular scratching or scurrying, they are often travelling through floor voids from a hidden entry point, frequently linked to drains.
► Can defective drains really cause rats in walls and attics?
Yes. Rats can exit broken drain pipes or damaged chambers near the foundations, then move into cavity walls and up into attics using service gaps and voids.
► What are the signs a rat problem is coming from the sewer?
Repeat infestations after baiting, no obvious outside entry holes, foul odours, slow drains, recurring blockages, and activity centered around kitchens, extensions or utility areas.
► What is a CCTV drain survey and how does it help with rats?
A CCTV drain survey uses a camera to inspect pipework and chambers. It helps pinpoint cracks, open joints, collapsed sections or broken manholes that give rats access.
► What if another drain company said “the drains look fine”?
Some surveys miss side branches, hidden junctions or buried chambers. A full investigation maps the system and checks every relevant section, not just the main run.
► Do traps and poison get rid of rats under floor permanently?
They can reduce numbers, but if the entry point is not repaired the infestation often returns. Long-term control usually requires proofing and drain repairs.
► Is it safe to lift floorboards or tiles to find a rat entry point?
This should be planned and done professionally. Repairs can be intrusive, and we always advise where reinstatement may not match the original finish.
► I have a bad smell in the kitchen and scratching under the floor. Could it be rats?
It could. Odours can come from urine, droppings, or a dead rodent in a void. A site inspection is the quickest way to confirm.
