Documents for a dwelling containing a known bat roost

If bats are roosting in your house, the bat roost house works documents you need fall into two separate stacks: the ones that go with the planning application, and the licence that has to follow the permission before a single tile comes off. The roost is protected whether or not you knew about it, and disturbing it or damaging it is a criminal offence under the Conservation of Habitats and Species Regulations 2017 and the Wildlife and Countryside Act 1981.

That sounds alarming. In practice thousands of loft conversions and re-roofing jobs proceed lawfully every year with a roost present. What they have in common is that the owner found out early.

Why the roost changes the whole programme

A confirmed roost adds two fixed elements to the programme that cannot be compressed: a survey season and a licence determination period.

The survey season runs from spring to late summer. If you discover the roost in October, the emergence surveys cannot happen until the following May, and the licence application cannot be made until the surveys are complete. A project that would have taken four months takes fourteen.

The licence period adds more. Natural England's determination of a mitigation licence takes weeks, and the licence cannot be granted before planning permission exists, because the licence assesses a scheme that has consent.

So the sequence is fixed: survey, then planning application with the survey and mitigation strategy, then permission, then licence, then works. Every attempt to shortcut it ends in a stop notice or a refused application.

Preliminary roost assessment and emergence surveys

The first step is a preliminary roost assessment, which can be done at any time of year. An ecologist inspects the building inside and out for bats, droppings, staining, feeding remains and potential access points, assesses the roosting suitability of the structure, and looks at the surrounding habitat.

The assessment produces one of three outcomes: negligible suitability, in which case no further survey is needed; some level of suitability, which triggers emergence and re-entry surveys; or confirmed roost, which goes straight to characterising the roost.

Where surveys are needed, the number of visits follows the roosting suitability of the building under the Bat Conservation Trust good practice guidelines. A building of low suitability normally needs one survey visit. Moderate suitability needs two. High suitability needs three, spread across the season rather than clustered in one week.

Each visit is either a dusk emergence survey, with surveyors positioned to watch every elevation as bats leave, or a dawn re-entry survey. Detectors record the calls, and the analysis identifies the species. Our note on preliminary roost assessment against emergence survey sets out what each stage produces.

The survey season and what it fixes

The emergence survey window runs from May to September, with May to August the period when results are most reliable, because that is when bats are using summer roosts and maternity roosts are active.

Surveys outside the window do not produce usable evidence, and an ecologist who offers them in March is not doing you a favour. Weather matters too: surveys are invalid in rain, in strong wind, or when the temperature at sunset is too low, which loses evenings from an already short season.

What the surveys fix is the character of the roost, and that determines everything downstream. A small number of common pipistrelles using a gap under a ridge tile is a different proposition from a maternity roost of brown long-eared bats in the loft void. The species, the roost type, the numbers, the access points and the seasonal use all feed into the mitigation design and into which licensing route is available.

Mitigation strategy and the licence route

The mitigation strategy sets out what will be lost, what will replace it, when the works can happen, and how the bats will be excluded safely.

Typical measures include timing works outside the maternity season, soft-stripping roof coverings by hand under ecological supervision, retaining or reinstating access points, installing bat boxes or integrated bat tubes, using breathable roofing membrane of a type that is not hazardous to bats, and avoiding treated timber products that are toxic to them.

Two licensing routes exist. A bespoke European protected species mitigation licence from Natural England is the standard route, assessed against three statutory tests: that the work is for a permitted purpose, that there is no satisfactory alternative, and that the action will not be detrimental to maintaining the favourable conservation status of the species. For low-impact situations there is a class licence route that a registered consultant can operate directly, which is faster, but it is limited by species, roost type and numbers, and the consultant has to be registered for it.

Ask your ecologist at the outset which route your roost is likely to fall under, because the difference in programme is weeks against months.

Who must hold the licence

The licence is held by a named ecologist who is suitably experienced and holds the relevant Natural England registration, not by you and not by your builder. They are the person legally responsible for supervising the works.

This is a legal requirement rather than a recommendation. Works affecting a roost carried out without a licensed ecologist supervising are an offence, and the fact that a planning permission exists is no defence.

Get the appointment right at the start and keep the same ecologist through survey, mitigation design, licence application and supervision. Changing consultants between stages means the incoming ecologist has to satisfy themselves about somebody else's survey data before they will put their name to a licence.

Documents for the planning application itself

For a householder scheme affecting a roost, the submission normally includes:

• The preliminary roost assessment and the emergence and re-entry survey report, with dates, weather conditions, surveyor positions and species identified
• A bat mitigation strategy showing the works, the timing, the supervision arrangements and the replacement roosting provision
• Drawings showing the retained and new roost features, at a scale where an ecologist can see the detail
• A statement addressing the three licensing tests, so the authority can satisfy itself that a licence is likely to be granted

That last item is the one applicants miss. The authority has a duty to consider the licensing tests before granting permission where a European protected species is affected, so an application that leaves them unaddressed invites a delay while the case officer asks for the point to be covered.

PlanScope can draft a Bat Survey report and a Protected Species Survey structured to the headings that authorities and ecologists expect, but the survey work and the licence are legally reserved for a licensed ecologist, and the draft is a starting point for that professional rather than a substitute for them.

Conditions and post-works monitoring

Expect a condition requiring the works to be carried out in accordance with the approved mitigation strategy, and often a further condition requiring the replacement roosting provision to be installed before the roof is completed and retained thereafter.

Monitoring conditions are increasingly common. They typically require inspection of the replacement provision in one or more subsequent survey seasons, with a report to the authority. Budget for it, because it falls after you have moved back in and after the builder has gone.

Keep the licence return too. Natural England requires a report at the end of the licensed works, and that document, together with the monitoring reports, is what a future buyer's solicitor will want to see. Our note on what reviewers check in bat emergence survey results covers the quality points that come up most often. You can see the wider set of documents a constrained householder scheme attracts across the 66 report types by category.

PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. Surveys and mitigation licences for bats require a suitably licensed ecologist under the Conservation of Habitats and Species Regulations 2017, and qualified professional input is legally required for this work.