Persistent rat infestation in Beckenham block of flats case study

Rat infestation in Beckenham case study | Rat pest and drainage survey | Block of flats pest control South London | Soil vent pipe defects and rat ingress

Pests do not discriminate from one building to the next. With the volume of flats London has across the city, there’s no wonder that Mercury Pest Control often sees rodent issues. We recently completed a complex pest and drainage investigation at a South London residential block in Beckenham. 

Recurring infestation and contractor failures

We were called to a residential block in Beckenham and it quickly became clear that the loft space was heavily invested with rats. The top-floor residents had been frequently distressed by constant noises in the walls and scurrying in the ceiling. This mostly occurred at night as that is when rodents like to move freely through the structural cavities. 

This issue had been treated on multiple occasions by other pest control companies by standard bearing and surface treatments. However, these methods failed to solve the problem as they did not address or fix the root cause. 

Mercury Pest Control arrived and conducted a comprehensive investigation, both of the structure of the building and through the drainage system. This is how we identified the entry points the rats were frequently and repeatedly using. 

Rodents and their entry points to high rise flats

Through this investigation we identified (quickly) the root cause of the issue, what the previous pest control companies had overlooked. The plumbers had left two soil vent pipes in the loft space wide open. 

Specifically, an air admittance valve (commonly known as a Durgo valve) on the main soil stack was left open and unsealed by the installation team. When these valves are missing, it creates the perfect entry point for rodents. They frequently exploit unsealed or cracked drainage pipes and valves to climb out of the drainage systems and follow the warmth to building voids. 

So, not only with these valves missing were the pipes leaking foul and possibly hazardous odours into the loft space, but they were also providing easy access to rats as they entered the warmth of the loft space and spread throughout the wall cavities. 

 

Phase 1: Controlled rat activity, removed hazardous waste and sanitised the space

It was very clear to the team that this issue and infestation was well established. Rats had contaminated the loft insulation with rat droppings and urine which resulted in a biological hazard.

Mercury Pest Control’s first step was to ensure the infestation was controlled and removed. Then focused on completely clearing all of the hazardous waste, and decontaminate the area. 

Handling heavily soiled loft insulation creates a hazardous environment and health risks, clearing this type of waste requires a specialised process:

1. We set traps to capture and control the rat infestation
2. We securely cordoned off doorways and communal access paths to isolate the hazardous waste during removal
3. We prepped and protected all areas in the flats directly beneath the loft space before any waste was moved through the building
4. We carefully removed the deceased pests and stripped out the contaminated insulation and we bagged, and disposed of it in accordance with hazardous waste regulations
5. We cleaned and sanitised the entire subfloor and timber structure of the loft
6. We then cleaned and sanitised all communal corridors and lower flat entryways again after the works were completed to ensure total safety for all occupants

controlled the activity in the loft space by using traps and removing the

Phase 2: Closing the rats access and stopping the infestation from returning

With the loft space thoroughly cleaned, and all hazardous waste removed we then needed to stop this from happening again. 

To ensure rats could no longer enter the building structure from the sewer system, we:

1. Correctly fitted and sealed air admittance valves to the open stacks in the loft space, eliminating foul odours and blocking the elevated entry point.
2. Installed specialist stainless steel rat blockers within the main drainage chambers. These non-return valves allow waste to flow out freely while physically preventing rats from travelling up from the main sewer line.

Permanent end to the rat infestation and long-term relief

By removing the biohazard, sanitising the roof void, sealing the open soil stacks, and securing the main inspection chambers with rat blockers, Mercury Pest Control completely neutralised the infestation.

Mercury Pest Control have since conducted follow-up checks, and we are pleased to report that no residents have heard or seen any further rat activity.

Ultimately, the property managers and tenants were delighted that our team thoroughly diagnosed and permanently resolved an issue that had stumped multiple previous pest control contractors.

Preventing rat infestations and drainage pest issues in South London properties

Rats, mice, and other persistent pests are often signs of hidden drainage or structural defects. Standard baiting or surface trapping will never resolve a rat problem if rodents can breach open soil pipes or unsealed Durgo valves in your building’s drainage system. Proper diagnostic surveys are essential to protect your property the first time.

So, if you are experiencing:

• A persistent rat infestation in Beckenham, South London, or Surrey
• Unexplained scratching or movement noises in loft spaces or wall cavities
• Unpleasant drainage smells coming from lofts or internal voids
• Recurring pest issues after previous pest removal companies have failed
• Pest problems linked to faulty soil stacks, unsealed pipes, or drainage chambers

Mercury Pest Control delivers professional pest management, getting to the root cause of the issue and resolving it for good.

Contact Mercury Pest Control today:

• 📞 Call: 0208 166 5110
• 📩 Email: info@mercurypestcontrol.co.uk
• 📍 Serving: Businesses and residents across all London and Surrey postcodes

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