How Do You Find Where Rats Are Getting Into a House?

Start With the Drains

In most of this area, rats indoors came from below. So the first look is at the drainage: lift the inspection chamber cover and check the benching and the channel for damage, look for a redundant connection from a removed outside toilet or an old extension that was never capped, and check the gullies.

The tell is smear marks — dark greasy deposits where a rat has repeatedly squeezed past the same point. Rats are creatures of habit and they leave a polish on a route they use.

Then the Base of the Building

Air bricks with broken or missing grilles. The gap where the soil pipe passes through the wall. Cable and service entries. The joint where a later extension meets the original brickwork, which almost never gets sealed properly. The threshold under a garage or side door.

Anything a thumb fits into is worth treating as a candidate. Rats do not need much and they will make a gap larger if it is nearly right.

Read the Evidence, Not Just the Holes

Smear marks along a run. Droppings collected in a line rather than scattered. Gnawing on something that is not food — plastic pipe, timber, cable sheathing. Runs worn through long grass or across a border. Disturbed insulation in a loft, and tunnels through it.

The evidence tells you the route, and the route leads to the opening. Hunting for holes without reading the runs first is how people miss the one that matters.

Work Upwards

Rats climb. Check where a downpipe passes an eaves gap, the point where an extension roof meets the main wall, open eaves courses, and any lifted tile. Trees and fencing that reach the roofline are routes up.

Loft insulation is worth looking at properly rather than from the hatch — runs through it are obvious once you are in there and invisible from the ladder.

What to Do With What You Find

Do not seal anything while there is activity inside. Proofing an occupied building traps rats in it, and that is worse than where you started.

Deal with the animals, then close the openings. Rodent proofing is £180 for up to an hour and covers rats, mice and squirrels. Where what you have found is a broken drain or a failed roof, that is a drainage contractor or a roofer, and we will tell you which rather than quoting proofing for it.