This was not a quick-fix rat control process. We had no way into the pipe via an inspection chamber, and the house had been extended over the main sewer. This gave us no external access or options.
Rats in the walls of a newly constructed kitchen extension left few clues as to the location of their entry. We checked all external surfaces for entry points and the building exterior had no entry points other than the front and rear doors.
We checked the only external sewer chamber on the neighbour’s driveway and it provided access to the neighbour’s drains and the main sewer line but not the customer’s line.
Fortunately for all concerned we revealed the chamber to discover it was full, just an inch from overflowing, indicating a blockage downstream. Wessex water swiftly attended and cleared the line, but it was still bad news. The sewer’s condition was fine, but the customer’s drains joined the sewer beneath the kitchen extension, making up-stream inspection into the house impossible.
Internally, we located the soil and vent pipe from the upstairs bathroom toilet and located a ground-level access point, hidden behind a plasterboard partition.
Now we were able to get our drain cameras into the line and survey it downstream. Our forensic search of the drains revealed not one but two redundant gully lines where the rats were likely getting in!
We knew where the line connected to the sewer and terminated in the house which gave us an approximate straight line. We also knew from houses on either side, where the original external gullies were. We worked out the angle of the redundant lateral gully branches and calculated exactly where the gullies would likely be under the extension.
After countless measurements and a little educated luck, we were ready to sacrifice a pristine floor tile. The customer only had a few spare, so we needed to be precise! Everyone held their breath as the SDS Chisel chipped its way down to the Damp Proof Membrane (DPM).
A quick tap on the DPM and it sounded very hollow! As we cut through the membrane it revealed the remnants of a 6mm plywood cover over the open gully and tunnels gnawed through the insulation board beneath the floor by countless rats. This provides the answer to many people’s question, “how can rats get out under a concrete floor?”. Simple answer, “They gnaw”.
The rats had gnawed through the 6mm plywood covers that the builders used to seal the gullies. Rats then gnawed their way through the foam insulation board above until they finally found their way into an underfloor void in an adjoining room and finally a wall void which took them into a ceiling void and the attic.
As usual, our measurements were spot on and we revealed and sealed the open drains permanently—no more Bait-Stink-Flies-Repeat for this customer. Kitchen rats love to stay undisturbed under kitchen counters behind the plinths.
Houses with prior rat ingress problems will often have old bat trays under kitchen counters.
It’s always worth remembering that rodents don’t have parachutes. Just because they are in your attic or other voids within your home or building, it doesn’t mean you start controlling them there.
Always look for the entry point and expect the unexpected.
This job highlighted to all involved the technical nature of our work.
After visiting hundreds of homes and businesses over the years, the principles of what we do remain the same, but the resources required to solve each problem vary greatly at times.
The sewers are the reservoirs of rat activity in urban environments, making drainage skills more important than a bait-only approach that stinks out your house and doesn’t actually solve anything.
Always demand builders show you that they have sealed redundant drains, etc, (concrete and glass is a good mix) before they cover them and always keep spare floor tiles – you never know when you might need them!
As always we are here to help you with all your pest problems and would be delighted if decide to give us the chance to try and solve your pest management problems. Get in touch today and thank you for visiting our blog.
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