Can squirrels damage a roof?

What squirrels actually damage

A squirrel in the roof is rarely a quiet visitor. Squirrels gnaw constantly, and a loft offers soft timber, warm insulation and plenty of material for a nest. The damage tends to fall into four groups.

• Timber. Fascia boards, soffits and the ends of rafters are chewed to enlarge an opening. Once the paint is broken, rain gets to bare wood and the rot starts.
• Insulation. Mineral wool is pulled apart and packed into a nest. Where it is thin or missing, the ceiling below gets colder and damp can follow.
• Cables. Wiring in the loft can be stripped of its sheathing. Damaged cable is a risk to the electrics, so have an electrician look at it before anything else is done.
• The covering. A loose slate or tile can be lifted by a determined animal, and a lifted tile leaves a gap that wind and rain can use long after the squirrel has gone.

None of this is dramatic on the day it happens. It is a slow loss of weather protection, which is why a scratching noise overhead deserves attention early.

How squirrels get in

Squirrels climb almost anything, then look for the weakest spot at the top of the wall. The usual entry points are all places where one part of the roof meets another.

At the eaves, the gap between the soffit board and the wall plate, or a rotten section of fascia, is easy to widen. At the verge, where the slope finishes against a gable wall, a loose or cracked cement fillet lets an animal push under the tiles. Along a wall or chimney, the flashing (a lead strip dressed over the joint) can lift at its edge. Squirrels also find gaps beside pipes, at ridge ends and around old vents that were never fitted with a cover.

On older Bath houses the likely places include an eaves detail that has dried and shrunk over many years, or a parapet gutter wall with open joints. Parapet gutters are lined troughs hidden behind a stone upstand along the eaves. If its stonework has opened up, the gap is a ready-made doorway.

Overhanging branches and a nearby wall or drainpipe give a route to the roof, so look at what the animal climbed as well as what it entered.

Signs you have squirrels rather than something else

Squirrels are active in daylight, so scratching, scampering and thumping in the loft often come in the morning and early evening. That separates them from rats and mice, which are mainly heard at night. Other signs are:

• Chewed edges on fascia, soffit or the timber around a vent.
• A nest of twigs, leaves and torn insulation in a corner of the loft.
• Droppings and a smell of urine near the nest.
• Damp stains on the ceiling beneath a spot where insulation has been dragged away.

Look from the ground first with binoculars, because the outside often shows the entry point before you go anywhere near the loft. Stay off the slope while you investigate. If you can see a damaged board or a lifted tile from the garden, that is enough to describe on the phone. Our page on storm damage to roofs explains how a make-safe is arranged when the covering has been opened up.

Check before you seal anything

Never block a hole while there might be an animal behind it. A trapped squirrel will chew harder to get out, and it may die in the roof space. Young animals left behind are another problem. Squirrels often nest in spring and again in late summer, so a hole sealed at the wrong moment can strand a litter.

The animal itself is a job for a pest controller, who can trap it or fit a one-way door so that it leaves and cannot come back. The roof repair then follows.

The same caution applies to other wildlife. Roosting bats and nesting birds are covered by wildlife law, and a gap that looks like a squirrel hole may be used by either. If you have any doubt, read the government guidance on bats before any work starts, because disturbing roosts can be a criminal offence.

How entry points are sealed and the damage put right

Once the loft is clear, the work is easy to describe and slower to do well. Every gap the animal used is closed with something it cannot chew. Foam, plastic and soft sealant do not last, because squirrels tear through them. Stainless or galvanised steel mesh, fixed mechanically with screws or clips, does.

The repair usually runs in this order:

1. Find every gap, not only the obvious one, because a squirrel that is shut out of one hole will test the next weakest place.
2. Cut out chewed or rotten timber and replace it with sound wood, painted or primed so the new board lasts.
3. Refix lifted tiles or slates and bed or refix any loose verge or ridge detail.
4. Dress lifted flashings back and renew any lead that has been torn.
5. Fit mesh behind eaves vents, and under gaps at the eaves that must stay open for ventilation.
6. Replace insulation that has been shredded, once the nest has been cleared out.

On an older roof, the repair should match the existing covering. Slate is repaired in slate, and a stone verge is repointed in lime mortar rather than patched in a harder cement mix. That is part of restoring the roof to its original build, rather than closing the hole in whatever is nearest to hand.

Keeping them out afterwards

The best protection is a roof in good order. A fascia that is sound, tiles that sit tightly and flashings that lie flat leave nothing for an animal to push on. Cut back branches that reach the roof, so there is no easy jump from tree to eaves. Keep the gutters clear, because a blocked gutter soaks the fascia and softens the timber that squirrels then chew.

If neighbours have the same problem, it may help to know that animals move along a terrace. A gap in a shared roof or a neglected party wall can feed the problem on both sides, and our page on a neighbour's dangerous roof covers what to do when the fault is next door.

Once the entry point is found and the loft is clear, our survey costs nothing and comes with photographs of the chewed timber and the repair we propose. A fixed written price follows, and the repair closes the gap at the eaves or verge with metal mesh or sound timber that a squirrel cannot chew back through. For the wider range of repairs we carry out in the area, see our roof repairs in Bath page.