Mouse Proofing - How to Stop Mice Getting Back Inside

The First Fortnight: Do Not Seal Anything Yet

Wait until the follow-up confirms activity has stopped. Sealing while there is anything still inside leaves mice in the cavity, where they die and smell for a fortnight.

What to do instead: move dry goods into hard containers, lift pet bowls overnight, deal with the residue under and behind the units rather than the crumbs on top, and keep a note of anything you hear and where. That note is genuinely useful at the follow-up.

Straight After the Follow-Up: Proof, Inside and Out

This is the moment, and most people miss it. The survey has just established exactly which openings were in use, so an hour of proofing now is worth several hours done cold six months later.

Inside: the pipework under the sink, behind the boiler, the airing cupboard, the kickboard void, the loft hatch surround, and in a flat the soil stack boxing. Outside: air bricks, thresholds, service entries and the extension junction. Rodent proofing is £180 for up to an hour.

The Materials, Because This Is Where It Fails

Not expanding foam, which they chew through in days and which hides the gap from later inspection. Not steel wool alone, which rusts and works loose. Not silicone, which they gnaw.

Rodent-resistant mesh packed properly and finished with mortar or a fitted plate, allowing for pipe movement and heat. If a gap has been filled with foam at any point in the past, treat it as open.

The Following Summer: The Annual Check

Late summer is the time, before the autumn influx. Walk the perimeter and look at the air bricks, thresholds and service entries. Take the kickboards off and look behind them. Check under the sink and behind the boiler with a torch held at a shallow angle.

Test with a biro — if a pen fits, a mouse fits. Twenty minutes once a year is what separates households that had mice once from households that have them every October.

The Ongoing Habits

Dry goods in hard containers rather than bags or boxes. Pet food lifted overnight and not stored in a bag on the floor. Bird feeders sited away from the house with a catch tray. Bins closed and not left open in a porch or garage.

And in a flat or a terrace, keep an eye on the communal parts, because a bin store with a gap into the risers will supply mice to every property on the stack regardless of what you do inside yours.