About this guide
Grey squirrels are the most common cause of unexplained loft noise in UK properties adjacent to woodland, parks, and gardens with mature trees. This guide covers the full range of signs that indicate a grey squirrel infestation — from the specific sounds they make in a roof void to the physical evidence they leave behind — and explains how to distinguish squirrel activity from rats or mice when the cause is not immediately obvious.
Most grey squirrel infestations in buildings are first noticed through sound — the distinctive noise of an animal moving across a timber ceiling at speed, typically in the early morning or late afternoon. But by the time sound is obvious enough to prompt action, squirrels may have been using the loft space for weeks and have already caused significant damage to insulation, cables, and building fabric. Knowing what else to look for — particularly on a routine roof inspection or during loft access for another purpose — helps identify the problem earlier and at lower cost.
Sounds: What Squirrels Sound Like in a Loft
Grey squirrels produce a distinctive pattern of sound in roof voids. The most characteristic is a rapid, bounding movement across ceiling joists — heavier and faster than a mouse, with a characteristic thud-thud-thud rhythm as the animal's feet land on each joist. This is most pronounced at the two main activity peaks: two to three hours after dawn (typically between 6am and 9am) and two to three hours before dusk.
Gnawing sounds are also common — a persistent, rhythmic chewing on hard surfaces. Grey squirrel gnawing sounds deeper and more forceful than mouse gnawing, and unlike mice, which tend to gnaw intermittently at night, squirrels will gnaw during daylight hours. Scratching sounds at a specific point — often near an entry point or where a drey is being constructed — indicate active nest-building behaviour.
Vocalisations are occasionally audible from inside the property: grey squirrels produce a sharp, repetitive bark-like alarm call. This is more often heard from outside the building but can be audible inside during territorial disputes near the roofline. A single squirrel in a loft is quieter overall than a nesting female with young, who will move more frequently between the drey and external foraging routes.
Grey squirrel activity is concentrated during daylight hours — if loft noise occurs primarily at night, rats or mice are more likely. Squirrel activity typically produces a heavier sound than mice (which are light and fast) and a more rapid, bounding pattern than the slower, more deliberate movement of rats. The timing of noise is often the most reliable first indicator of which species is involved.
Physical Evidence in the Loft
Grey squirrel droppings are cylindrical and slightly tapered at both ends, typically 8 to 12 millimetres long and 4 to 5 millimetres in diameter. They are medium to dark brown when fresh, becoming lighter and more crumbly as they dry. Squirrel droppings are frequently confused with rat droppings — both are similar in size and shape — but grey squirrel droppings tend to be lighter in colour and have a less pungent odour than rat droppings. Mouse droppings are significantly smaller (3 to 5mm) with more pointed ends.
Nesting material in a grey squirrel loft infestation is unmistakeable: a substantial, roughly spherical pile of torn loft insulation (glass fibre or mineral wool pulled into loose fibres), bark strips, leaves, and any soft material that was stored in the loft — cardboard, fabric, paper. The drey is typically positioned in a corner or against a wall, 20 to 60 centimetres in diameter. A breeding drey used by a female with young will be larger and more densely packed.
A grey squirrel drey in a loft space can destroy an area of glass fibre insulation equivalent to several square metres within a single breeding season, as the animal gathers and compacts material for the nest.
— British Pest Control Association (BPCA) Technical Guidance, 2021
Gnaw Damage and Entry Point Evidence
Gnaw marks from grey squirrels are larger and deeper than those made by mice and have a more irregular, chiselled appearance than the finer marks made by rats. Common gnaw targets in loft spaces include: timber roof members (particularly where cables run across them), electrical cable PVC sheathing (the most serious damage category), plastic water pipe insulation, and any hard surface the animal uses repeatedly to maintain incisor length.
External entry point evidence includes: fresh gnaw marks on timber fascia boards or soffits at the roofline, displaced or cracked roof tiles with squirrel-sized gaps at the edges, compressed dirt or fur traces at gap edges where squirrels have repeatedly passed through, and scratch marks on paintwork or render immediately below an entry point. Squirrel entry points frequently have a worn, dark appearance at the edges where the animal's body oils have accumulated over multiple entries.
External and Garden Signs
Garden activity signs that often accompany a building infestation include: bark stripped from trees in a spiral pattern around the trunk or from branches (most visible on smooth-barked species like beech or sycamore); shallow excavations in flower beds or lawn where cached nuts have been retrieved or deposited; raided bird feeders with damage to feeder components; and squirrels observed running along the roofline or entering under the eaves.
If squirrels are regularly seen on the roof or running along gutters, they are almost certainly investigating or using an entry point in the roof fabric. A squirrel that disappears under the eaves and does not immediately re-emerge is one that has an established access route and is entering the loft space, not simply investigating the surface.
Confirming the Species and Getting Professional Assessment
The combination of daytime noise, a substantial drey, cylindrical droppings of 8 to 12 millimetres, and external entry evidence strongly indicates grey squirrel rather than rat or mouse activity. However, mixed infestations — grey squirrels and rats simultaneously using the same roof void — are not uncommon in properties with multiple access points, and both species may be present without either being immediately obvious.
Professional pest controllers in Sheffield and South Yorkshire carry out systematic loft inspections that identify all species present, locate all entry points, assess the extent of damage, and determine the appropriate control programme. Early professional assessment means control work can begin before a single pair of squirrels becomes an established breeding colony — significantly reducing both the cost of the programme and the extent of repair work required afterwards.
Frequently Asked Questions
What do grey squirrels sound like in a loft?
Grey squirrels in a loft produce a heavy, rapid bounding movement across ceiling joists — a characteristic thud-thud pattern that is heavier than mice and faster than rats. Activity is concentrated at dawn and late afternoon. Persistent daytime gnawing on timber or cables is also common. If loft noise occurs primarily at night, rats or mice are more likely than squirrels, which are diurnal animals.
What do grey squirrel droppings look like?
Grey squirrel droppings are cylindrical, slightly tapered at both ends, 8 to 12 millimetres long, and 4 to 5 millimetres in diameter. Fresh droppings are medium to dark brown; dried droppings become lighter and more crumbly. They are similar in size to rat droppings but typically lighter in colour and less pungent. Mouse droppings are much smaller (3–5mm) with more sharply pointed ends.
How do I tell if squirrels or rats are in my loft?
The key differences are timing and movement pattern. Squirrels are active during daylight hours — noise from squirrels is concentrated around dawn and late afternoon. Rats are primarily nocturnal, with most activity after dark. Squirrel movement is fast and bounding; rat movement tends to be slower and more cautious. Squirrel droppings are lighter in colour than rat droppings and have less odour. A pest controller can confirm the species from inspection.
What does a squirrel nest look like in a loft?
A grey squirrel drey in a loft is a substantial, roughly spherical pile of torn loft insulation, bark strips, leaves, and soft materials collected from storage. It is typically 20 to 60 centimetres in diameter and positioned in a corner or against a wall. A breeding drey used by a nursing female will be larger and more densely packed. It is much larger than a mouse nest and more structured than a rat's nest.
What are the signs of squirrels getting into a roof?
External signs of roof entry include: fresh gnaw marks on timber fascia or soffit boards at the roofline, gaps under displaced or broken roof tiles, dark worn patches at gap edges where the squirrel has repeatedly passed through, and squirrels observed running along the roofline and disappearing under the eaves. Internally, a combination of loft noise, droppings, nesting material, and cable or insulation damage confirms entry.
What damage do squirrels cause to electrical cables?
Grey squirrels gnaw on PVC electrical cable insulation — not because they eat it, but because gnawing is a constant biological need driven by continuously growing incisor teeth. Gnawing strips the insulation from cables, exposing the live conductor underneath. Damaged cables in a loft space represent a genuine fire risk. Any electrical cables running through a loft space with confirmed squirrel activity should be assessed by a qualified electrician before the space is re-insulated.
How quickly should I act if I suspect squirrels in my loft?
Act as soon as you suspect activity. Grey squirrels breed twice a year, and a single pair that gains access in late summer can establish a breeding colony by the following spring. Early action — professional inspection, trapping, and proofing — costs significantly less than resolving a multi-animal infestation with an established drey and extensive cable or insulation damage.
Contact a pest controller for a survey when you first notice the signs rather than waiting to confirm the problem with certainty.