Why Do Rats Keep Returning to the Same Buckden Property?

Recurrence has a small number of causes and this is the one people find hardest to believe, because they looked at the gap and judged it too small.

Fifteen Millimetres, and Then More

BPCA's guidance is to eliminate gaps around pipes and under sheds, because rats only need a gap of 15mm to gain entry to a structure. That is the requirement for an animal to pass through as it is.

It is not the ceiling. BPCA also note that rats have to gnaw in order to keep their teeth in shape, and they are not shy about what they gnaw on. So an opening that is nearly big enough does not stay nearly big enough.

Where It Usually Happens

• Around pipe and cable entries, where the mortar or filler is soft and the gap starts small
• Under an external door, where a timber threshold has already worn
• At an air brick with a cracked plastic cover
• Where soft pointing has failed at ground level on older property
• At a soffit or barge board joint, reached from a fence or a branch
• Through expanding foam or sealant used to close a gap previously — both are a filler, not a barrier, and a rat goes through them without difficulty

Why the Treatment Was Not the Problem

A treatment deals with the animals present. It does nothing to the fabric of the building, and it makes no difference at all to a route that is still open. So the sequence looks like this, and it repeats:

1. Rats get in through a small gap.
2. Treatment clears the property. Everything appears solved.
3. The gap is still there, and it is now larger than it was.
4. The next autumn, when it turns cold, the route gets used again.
5. The householder concludes the treatment did not work.

What Actually Breaks the Cycle

Proofing, in metal, after the property is confirmed clear. Wire wool packed tightly into the gap and sealed over, a metal plate or mesh across a larger opening, a proper air brick cover, a metal or heavy bristle strip on a worn threshold.

We price proofing separately by time rather than bundling it in, precisely so it is your choice whether we do it or your own builder does. What matters is that somebody does, and that it happens after the treatment rather than before — sealing a building with an active population inside traps them in, and they gnaw their way out somewhere new.