The clearest signs of rats in an East London property are droppings the size of a large grain of rice or bigger, gnaw marks on timber and plastic, dark greasy smear marks along walls, and heavy scratching or thumping in floor voids after dark. Read them together, never one at a time.
Rat droppings are the primary identifier: dark brown to black, roughly 10 to 15 mm long, thicker than a matchstick, tapered at one or both ends, and left in groups along a regular route. Mouse droppings are much smaller, roughly 3 to 7 mm, thin, rod-shaped and scattered widely.
Freshness matters as much as size. A fresh dropping is dark, soft and slightly shiny; an old one is grey, dry and crumbles under pressure, so droppings that crumble throughout may be a historic problem rather than a live one. Wear gloves, and never sweep droppings dry, because dry sweeping puts contaminated dust into the air.
Six features separate the two species reliably: dropping size, gnawing pattern, smear marks, the character of the noise, the smell, and where in the building the evidence appears.
| Feature | Brown rat | House mouse |
|---|---|---|
| Droppings | Roughly 10 to 15 mm, tapered, clustered along runs | Roughly 3 to 7 mm, thin, scattered widely |
| Gnawing | Coarse, deep, on timber, plastic pipe, cable, mortar and door bottoms | Fine, shallow, small neat holes in packaging and skirting |
| Smear marks | Common — dark greasy bands along skirtings, joists, pipes and beam edges | Rare, and much fainter |
| Noise | Heavy scratching, gnawing and thumping in floor voids, ceilings and lofts | Light, fast scuttling and high-pitched squeaks in walls and cupboards |
| Smell | Strong ammoniacal smell where numbers build up | Distinctive musty smell, weaker unless the population is large |
| Where the evidence appears | Ground floor, cellars, floor voids, drains, gardens, bin stores, sometimes lofts | Anywhere, and often high up — cupboards, cavity walls, behind appliances |
| Access gap needed | Larger — a broken airbrick, a defective drain, a gap under a door | Very small — a gap the width of a pencil is enough |
That last row explains most misidentifications: a property with no external hole big enough for a rat, but persistent indoor activity, is usually either a mouse problem or a rat arriving through the drains rather than the walls.
Gnawing marks tell you the species, the location of the run and, sometimes, how long the problem has run. Rat gnawing is coarse and deep, with visible paired incisor grooves, and it appears on hard materials: timber joists, plastic waste pipe, cable sheathing, soft mortar and the lower edges of doors.
An enlarged hole with a polished edge and grease around it is an active run, not an old one, and fresh gnawing on painted timber shows pale, clean wood underneath where older damage has greyed. Gnawed cable insulation in a floor void or loft is a fire and shock risk, and it is the reason a rat problem is treated as urgent rather than unpleasant. Where cable is involved, a quick turnaround is the point rather than a convenience, because the risk sits live in the void until the run is found and the animals using it are dealt with.
Smear marks are dark, greasy bands left where a rat's flank repeatedly brushes a surface, formed from body oil, dirt and urine. They are one of the most reliable indicators of an established run, because they take repeated journeys by several animals to build up.
Look for them where a vertical surface meets a horizontal one: skirting against floor, the top edge of a joist, the length of a pipe run, the timber around a loft hatch. In a floor void, smears mark the line a rat takes between its entry point and a food source, which is the line a technician wants for trap and bait placement.
Noise tells you where the rats are, and the smell tells you roughly how long they have been there. Rat noise is heavy for the size of the animal: scratching, dragging, gnawing and audible thumps in a floor void, ceiling or loft, peaking after dusk and before dawn.
Location narrows the job. Noise below a ground floor points to a subfloor void, a cellar or a drain; noise in a first-floor ceiling points to the void between floors; noise overhead points to the roofline or a soffit gap.
Smell is a later sign. An established population produces a strong ammoniacal smell from accumulated urine, most noticeable in an enclosed cupboard, cellar or loft. A sweet, rotting smell is a carcass in a void, which has to be located and removed rather than masked.
Activity in floor voids and party walls matters because much of East London's housing is Victorian and Georgian terracing converted into flats, so one rat run can cross several homes without the animal going outside. Suspended timber floors, party walls, boxed-in soil pipes and continuous service runs connect flats that are legally separate.
Three consequences follow. First, in a converted terrace the signs of rats in an East London property often appear in a flat that is not the one being colonised, because the harbourage sits in a neighbour's subfloor or a communal riser. Second, treating one flat alone rarely works, because the population shifts along the void. Third, the entry point may sit in a part of the building controlled by a freeholder or managing agent.
Identification comes before treatment: a technician's first task is to confirm the species and map the run from droppings, smears and gnawing before anything is placed. Because that mapping is what a treatment plan is built on, it is worth getting someone in early: 247 Pest Control states that same-day attendance is available across London and that it responds to emergency enquiries 24/7, while noting that attendance time cannot be identical for every call. The purpose of that visit is to establish what the pest is, what treatment the property actually needs, and the soonest date the work can be done.
Judge severity on four measures: the amount and freshness of droppings, the number of separate runs, whether sightings happen in daylight, and whether activity is inside living space or confined to a garden, cellar or bin store.
Severity is what moves the price, not the postcode. 247 Pest Control publishes a pest inspection from £62 and rat control from £214 as starting points for straightforward domestic treatments, and names the variables that move them, from property size to access and urgency.
Severity carries a legal edge at the heavy end as well. The occupier of land must notify the local authority in writing where substantial numbers of rats or mice are living on or resorting to that land, so a heavy infestation brings a reporting duty alongside the treatment cost.
A single rat sighting does not prove an infestation inside the building, and it does not tell you the source. One rat seen in a garden, on a canal towpath or crossing a yard at dusk is consistent with an animal travelling, foraging or displaced by nearby building work.
What a single sighting does justify is an inspection: droppings, smears and gnawing at the points named above, plus the external envelope — airbricks, drain covers, gaps under doors, and any opening left by recent works.
Do not conclude the opposite either: no sighting at all does not mean no rats, because animals in a subfloor void or a drain may never be seen. The Housing Health and Safety Rating System (HHSRS) rates domestic hygiene, pests and refuse as a hazard in residential premises, and a local authority assessment turns on evidence of conditions, not on whether anyone has seen an animal.
Not reliably, but the noise narrows it. Rat activity sounds heavy for the size of the animal — dragging, gnawing and audible thumps in a floor void or loft — while mouse activity is a light, fast scuttle, often with high-pitched squeaks. Confirm with droppings, since dropping size is the primary identifier for both species.
Yes. In a converted Victorian or Georgian terrace, shared party walls, subfloor voids and boxed pipe runs let rats move between homes without going outside. Each occupier also has their own duty to notify the local authority of a substantial infestation on their land, so a neighbour's report does not cover you.
Report them to the landlord or managing agent in writing, with dates and photographs. A landlord is responsible for keeping the structure, exterior and the installations for water, gas, electricity and sanitation in repair, which covers the defective drain or damaged brickwork rats are using.
Usually, because misidentification costs more than the survey. A survey confirms the species, locates the run and the entry point, and produces a dated written record. The British Pest Control Association (BPCA) publishes Codes of Best Practice covering how member companies should survey, treat and report, and any firm's membership can be checked on the BPCA's own member register.