Can you block holes in a roof if bats might be present?
- Mar 5
- 3 min read
Small gaps in roofs are common in historic buildings.
Tiles shift over time, mortar deteriorates and ventilation openings appear. These gaps may seem like minor maintenance issues, but they can sometimes provide access points for bats.
For building owners the instinct is often simple: close the hole and solve the problem.
However, if bats are using the building, sealing those openings may be illegal.
Understanding how bat protection works helps avoid accidental breaches of wildlife law.
Why bats use small openings
Bats are remarkably small animals and can enter buildings through openings only a few centimetres wide.
Common entry points include:
gaps beneath ridge tiles
openings between slates
cracks in stonework
spaces behind fascias
ventilation gaps
Once inside, bats may roost beneath felt, between rafters or within narrow crevices.
These roosts are often used seasonally and may not be obvious during daylight inspections.
The legal position
Blocking access to a bat roost is illegal under wildlife legislation.
The law prohibits:
damaging a bat roost
obstructing access to a roost
disturbing bats while they are roosting
Because of this, sealing roof gaps that provide bat access can be an offence if bats are present.
Importantly, the law applies even if bats are not visible when the work is carried out.
This is one reason why bat legislation is often described as unusually strict compared with most other building regulations.
When roof gaps can be sealed
If it has been confirmed that bats are not using the building, roof repairs can normally proceed without restriction.
This is why ecological surveys are sometimes recommended before sealing openings in historic roofs.
Once it is clear that the building is not used as a roost, gaps can be repaired as part of normal maintenance.
When bats are present
If bats are confirmed in the building, entry points cannot simply be sealed. Instead, mitigation measures are usually required.
These might include:
maintaining existing access points
installing bat access tiles
providing bat boxes nearby
adjusting the timing of roof repairs
In some cases a wildlife licence from Natural England may be required before work proceeds.
Timing and project planning
Bat mitigation often affects the timing of roof repairs. Certain works may only be permitted outside key periods such as the maternity season when bats are raising young.
This means roof repairs sometimes need to be scheduled carefully to align with ecological requirements.
Planning ahead can prevent unexpected delays.
Typical costs
Financial impacts usually arise from surveys and mitigation measures rather than the repair work itself.
Typical costs might include:
ecological surveys: £300–£1,500
bat access tiles or boxes: £50–£200 each
ecological supervision during works if required
These costs are generally small compared with the cost of repairing a historic roof.
Get it wrong — what happens?
If roof openings are sealed and a bat roost is damaged, the situation can escalate quickly.
Work may be stopped while the issue is investigated.
Ecological surveys may be required after the event, and mitigation measures may need to be implemented.
In serious cases legal action may be taken under wildlife legislation. While prosecutions are rare, enforcement action can cause significant disruption to building projects.
How are offences discovered?
Most wildlife cases come to light through:
neighbours reporting building works
ecological consultants
conservation officers
wildlife organisations
Bat activity around buildings is also easy to observe at dusk, particularly during summer months.
Because of this it is usually better to address the possibility of bats early rather than hope the issue does not arise.
Pest species and roof gaps
Not all animals entering roofs are protected.
Pigeons, squirrels, rats and mice often use similar openings but do not benefit from the same legal protection.
Where these animals are causing damage or infestation, roof gaps can normally be sealed once humane pest control measures have been taken.
The key distinction is that bats and certain other species are protected wildlife, while pest species can generally be controlled.
The Longnor Heritage approach
At Longnor Heritage we encourage building owners to take a calm and practical approach to wildlife issues.
If roof gaps may provide bat access, the safest course is to investigate before sealing them. A simple inspection or ecological assessment can often resolve the question quickly.
With sensible planning most roof repairs can proceed without difficulty while respecting the legal protection given to bats.
Historic buildings and wildlife have shared the same spaces for centuries. With the right approach they can continue to do so.
