Gnawing in a roof space is not random, and it is not indiscriminate either. There is a fairly consistent order of preference, and knowing it tells you what to expect to find.
What decides the order
Two things. Resistance — the material has to be firm enough to wear the incisors down and soft enough to give way, which is a narrower band than it sounds. And availability — it has to be at the height the animal travels at, in the open, on the route it takes anyway.
First: soft plastics and cable sheathing
Close to the ideal resistance, and cable is clipped along the tops of joists at exactly working height. Pipe insulation and tank lagging come into this group too, with the additional attraction that they double as nesting material. This is the group that matters, because it contains the fire risk.
Second: softwood at an edge
Battens, boarding edges, joist tops and the arrises of rafters — anywhere there is an edge to get purchase on. Squirrels work edges rather than flat faces, which is why gnaw damage on timber is so often on a corner rather than in the middle of a surface.
Third: the entry point itself
Whatever material the opening is made of, worked to enlarge it. Soffit board, fascia, verge undercloak, felt at the eaves. This is purposeful gnawing rather than incisor wear, and it is generally the heaviest single concentration of damage on a property.
Fourth: rigid plastics and thin metal
Vents, grilles, pipe, conduit and light plastic components. Slower work and entirely achievable. Thin sheet metal and lightweight flashing are not immune either, which is why proofing uses heavy mesh rather than anything light.
What they largely leave alone
Masonry, mortar in good condition, heavy steel, glass, and mineral wool — which is torn and shredded rather than gnawed, because it offers no resistance at all. That last point is why insulation damage looks so different from gnaw damage: one is excavation, the other is chewing.
Why the order is useful. It tells you where to look. Cable first, then timber edges, then the entry point — and it explains why an inspection that finds nothing on the rafters may still find plenty on the cable runs.
The one to act on
The first group. Everything else on this page is a repair bill; gnawed cable is a fire risk. Any flickering lights, tripping circuits, dead sockets or smell of burning means isolating that circuit and calling an electrician, whatever else is happening.
Questions
Do they gnaw because they are hungry?
No. Incisors grow continuously and have to be worn down, so it is maintenance rather than feeding.
Why the edges of timber rather than the faces?
An edge gives purchase. It is why gnaw damage on a rafter is usually on the arris rather than the flat.
Will they gnaw through steel mesh?
No. Heavy steel is outside the range that works for them, which is exactly why proofing uses it.
Squirrel Control Newmarket
Squirrel control in Newmarket is £280 fixed cost. Proofing work, where it is needed afterwards, is £180. Call 01502 630 122 and tell us what you have heard or seen.
For squirrel control in Newmarket, call 01502 630 122, or read the Newmarket squirrel control page.