Scratching in the Walls at Night in Great Shelford: Could It Be Mice?

Nobody wants to pay for a visit that finds nothing. Here are the non-animal explanations, in rough order of how often they turn out to be the answer.

Pipework and Heating

The commonest of all. Copper and plastic pipe expands and contracts as it heats and cools, and where it passes through a joist, a clip or a hole that is slightly too tight, it ticks, taps and creaks as it moves.

• The tell: it starts shortly after the heating comes on and again after it goes off
• It has a regularity to it that an animal does not
• It does not stop when you knock
• It happens at the same times every day, matching the timer

Timber Movement

A building warming during the day and cooling at night produces cracks, ticks and creaks from roof timbers, floors and the loft. It clusters in the evening as things cool, which is exactly when people are lying awake listening.

Wind

• A loose tile, ridge tile or slate
• A vent cowl or extract terminal turning
• A television aerial or satellite bracket
• A downpipe or gutter bracket
• Trailing ivy or a branch touching the roof or a wall — which sounds remarkably like scratching
• The tell: it correlates with the weather and stops when the wind does

Water

• Water hammer — a bang or knock when a tap or valve closes
• A dripping overflow inside a wall or into a void
• Air in the system, which gurgles and ticks
• A cistern refilling slowly overnight

Insects

Less common but real. A large beetle or a wasp trapped behind a panel, in a light fitting or in a wall void makes an intermittent scratching or buzzing sound that carries surprisingly well. Deathwatch and other wood-boring beetles make a faint ticking in old timber.

How to Rule Them Out

1. Log the times for four or five nights and compare against the heating timer and the weather.
2. Knock. An animal goes quiet and resumes; nothing on this page reacts at all.
3. Go outside and look at branches, ivy, aerials, vents and downpipes.
4. Turn the heating off for a night if that is practical, and see what changes.
5. Look for physical evidence. This is the decisive one — no droppings, no gnawing, no nesting material and no smell, after a proper look, argues strongly against a rodent.

Where you have done all that and are still unsure, a pest inspection and survey is a fixed cost and settles it, including the perfectly good outcome that there is nothing there. We would rather give you that answer than treat a property for a problem it has not got.