Barn conversions and the protected species living in them

A barn conversion protected species survey is not a box to tick at the end of the design. It is the item most likely to add a year to the programme, because the surveys that matter can only be done between roughly May and September and because a bat roost cannot be worked on without a licence from Natural England.

Old agricultural buildings are among the best bat habitat in the English countryside. Stone and timber barns with open ridges, mortise joints, gaps behind boarding and undisturbed roof voids provide exactly what several species need, and the same buildings support barn owls, swallows and other nesting birds.

Why barns are such good habitat

The features that make a barn attractive to convert are the ones that make it valuable to wildlife. A large unlit roof void with a stable temperature, plenty of crevices in the timber frame, gaps under ridge tiles and around lead flashings, and free flight access through openings that were never glazed.

Bats use different parts of a barn at different times of year. A summer maternity roost in the ridge may be occupied by a different species from the crevice roost in the gable, and a hibernation roost may be in the coldest corner of the same building.

Barn owls occupy lofts and open bays, and they are listed on Schedule 1 of the Wildlife and Countryside Act 1981, which means disturbance at or near an active nest is an offence in its own right.

When a survey is needed and which one

Start with a preliminary roost assessment. This is an inspection of the building, inside and out, by an ecologist looking for droppings, staining, feeding remains, pellets, whitewash and access points, and assessing the building's suitability. It can be done at any time of year, which makes it the first thing to commission.

The assessment produces one of three outcomes. Negligible suitability, in which case no further survey is needed and the ecologist says so in writing. Confirmed evidence of a roost, in which case you are into mitigation and licensing. Or potential suitability, which triggers emergence and re-entry surveys.

Commission a Bat Survey from a licensed ecologist. Surveys of roosts and any mitigation licence require a suitably licensed ecologist under the Wildlife and Countryside Act 1981 and the Conservation of Habitats and Species Regulations 2017. That is a legal requirement, and an AI-assisted draft report is a starting point for that ecologist rather than a substitute for one.

Where other species may be present, such as nesting birds in the surrounding structures or reptiles in adjacent rough ground, a Preliminary Ecological Appraisal covering the whole site scopes what else is needed, and a Protected Species Survey follows for anything the appraisal flags.

Survey seasons and the programme

This is the part that decides your timetable.

Current good practice guidance sets the number of emergence surveys by the suitability of the building, with more visits required where suitability is higher and visits spread across the season rather than clustered. Two surveys a fortnight apart in late August is not the same as two spread across the optimal period, and an ecologist will say so.

Miss the season and you wait until the following May. That single fact is why the preliminary roost assessment should happen before you buy the barn, not after the architect has produced a scheme.

The prior approval timing problem

Class Q conversions run on a prior approval application with a 56 day determination period. The prior approval matters listed in the Order do not include ecology.

That does not make the ecology go away, for two reasons.

First, the local planning authority has its own duty in relation to European protected species when exercising its functions, so it has to consider whether an offence is likely and whether a licence would realistically be granted. In practice most authorities ask for bat survey information on Class Q applications, and a refusal for insufficient information is common where none is provided.

Second, the criminal liability sits with whoever does the work, which matters more. Prior approval does not authorise damaging a roost. A builder stripping a roof containing a maternity colony commits an offence whether or not the council asked about bats.

The practical answer is to run the ecology work ahead of the prior approval application rather than in parallel with it, because the 56 day period is far too short to commission and complete emergence surveys.

Mitigation designed into the conversion

Mitigation works when it is part of the building rather than bolted on afterwards.

The usual approach for a bat roost is to retain a dedicated roost space within the converted building, typically a section of roof void kept separate from the habitable accommodation, unlit, unheated and undisturbed, with the original access points maintained or replicated. Access can be through a raised ridge tile, a gap at the eaves, an access tile or a purpose-made slot, sized and positioned as the ecologist specifies.

Materials matter. Breathable roofing membranes of certain types can entangle bats, so the ecologist will specify what is acceptable. Treated timbers need products that are safe once cured.

For barn owls, an alternative nest site, usually a box on a pole or within a retained outbuilding, with a clear flight line and away from roads, placed before works begin.

Lighting is the mitigation most often lost at the detailing stage. External lights on a converted barn can make the roost access unusable and sever a commuting route along a hedgerow. Design a scheme with low mounting heights, warm colour temperature, tight beam control, no upward spill and no light on the roost access or the hedgerow, and set it out in a Lighting Assessment or a lighting plan referenced by condition.

Licensing and who holds it

Where works will damage or destroy a roost, a European protected species mitigation licence from Natural England is required. The application is made after planning permission or prior approval is granted, because the licence tests include the absence of a satisfactory alternative, and the planning decision is part of demonstrating that.

The ecologist is named on the licence and the developer is normally the licensee, so both carry obligations. There is also a class licence route for schemes with low impact, available through registered consultants, which is faster where the case fits.

Allow time. Licence determination is not instant, and a licence that arrives in October when the mitigation requires works outside the maternity season pushes the roof works to the following year.

For barn owls there is no equivalent mitigation licence for disturbing an active Schedule 1 nest. The answer is to avoid, which means timing works outside the breeding period and providing an alternative site in advance.

What to submit and what gets conditioned

Submit the preliminary roost assessment, the emergence survey results, a mitigation strategy with drawings showing the retained roost space and access points, the lighting plan, and a method statement covering how the roof will be stripped and by whom.

Expect conditions requiring the mitigation to be implemented as approved, works to be carried out under ecological supervision, a licence to be in place before any works affecting the roost, and in some cases post-development monitoring for a defined period.

One honest uncertainty. How much survey effort a council requires on a barn with limited apparent potential varies, and ecologists differ on marginal buildings. The way to control that is to get the preliminary assessment done by an experienced bat ecologist and to have the reasoning written down, so that a request for further surveys can be answered with evidence rather than argument.

This is general guidance, not legal advice. Offences under wildlife legislation carry criminal liability, so check the position with a licensed ecologist and your local planning authority before any work starts.

To see which reports a barn conversion is likely to need, enter the postcode on PlanScope.

PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.