Preliminary Roost Assessment (PRA)
A preliminary roost assessment (PRA), also referred to as a PRA bat survey, bat scoping survey, phase 1 bat survey or bat roost assessment, is usually the first stage of bat survey work for planning applications across England.
This ecological site assessment supports early-stage environmental impact analysis. It helps determine whether buildings, trees or structures have the potential to support bats. Because bats and their roosts are legally protected under UK law, planning authorities require sufficient ecological information before deciding applications where potential risk is present.
A preliminary bat roost assessment is often commissioned during the design or pre-planning phase. It helps developers, homeowners and planning consultants understand ecological constraints early. It can also reduce avoidable delays later in the process. The outcome of the PRA helps determine whether additional survey work, such as a bat activity survey, is required.
ACP Consultants Ltd provides preliminary roost assessment services across England, delivering clear, planning-ready reports that align with recognised ecological guidance and support efficient decision-making.
We follow a simple, transparent process to ensure your project runs smoothly from the very first contact to the final report. Our approach is designed to provide you with clarity at every step, so you’re fully informed and confident in moving forward.
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Step 1: Request a Quote
Fill out our quick quote form or call us, and our team will provide a free, no-obligation quote, outlining the services tailored to your needs.
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Step 2: Confirm Your Booking
Once you approve the quote, simply return the booking form. We’ll schedule your survey and ensure all the details are taken care of.
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Step 3: Receive Your Report
After your survey is completed and payment is received, we’ll promptly issue your survey report, ensuring you get the results as quickly as possible.
In the past year, we’ve delivered over 750+ audit-ready reports supporting 400+ projects for developers, planners, and architects nationwide. We put quality over quantity and build lasting relationships based on trust, ensuring your planning applications are backed by robust evidence and delivered on time.
Do I Need a Bat Survey?
Understanding whether you need a preliminary roost assessment is an important first step in the planning process. In England, planning authorities follow national policy and ecological guidance to determine whether protected species surveys are required.
You may need a PRA bat survey where development could affect structures or habitats that are capable of supporting bats. This is not limited to rural areas urban and suburban sites frequently require assessment due to the presence of suitable features within buildings and surrounding landscapes.
Typical triggers include:
- Alterations to roofs, lofts or eaves where bats may roost
- Demolition of buildings, including garages, outbuildings or older structures
- Barn conversions or redevelopment of agricultural buildings
- Removal or management of mature trees with cavities or features
- Installation of external lighting near hedgerows, woodland or water
- Development within proximity to rivers, lakes, woodland edges or green corridors
In many cases, the requirement for a bat roost assessment is identified through planning validation checklists or ecological screening processes. Where there is reasonable likelihood of bats being present, planning authorities expect survey evidence to inform decision-making.
What Is a Preliminary Roost Assessment?
A preliminary roost assessment is a structured daytime inspection carried out by a qualified ecologist. It forms part of a wider ecological site assessment and contributes to biodiversity inventory and habitat suitability assessment work.
The purpose of the survey is not to confirm the presence of bats directly, but to assess whether a building or tree has the potential to support a roost. This is achieved through a combination of visual inspection, professional judgement and understanding of bat ecology.
During a preliminary bat roost assessment, the ecologist will carefully inspect features such as:
- Roof coverings, ridge tiles and soffits
- Cracks, crevices and gaps within brickwork or stonework
- Roof voids, loft spaces and internal structures
- Timber framing and cladding
- Tree cavities, splits and loose bark
In addition to structural inspection, the surrounding environment is assessed to understand its suitability for bats. This includes identifying commuting routes such as hedgerows and tree lines, and foraging habitats such as grassland, woodland or water features.
Evidence of bats, where present, may include droppings, staining, feeding remains or characteristic odours. However, absence of evidence does not confirm absence of bats, which is why a risk-based assessment is undertaken.
The outcome is documented in a preliminary roost assessment report, which classifies the site’s bat roost potential and provides clear recommendations.
The Bat Survey Process
Bat surveys follow a staged approach. This ensures planning authorities receive appropriate ecological information without unnecessary survey work.
This structured process helps identify potential constraints early. It supports proportionate environmental impact analysis. It also aligns with recognised guidance used in England.
The process usually begins with a preliminary roost assessment (PRA). This assesses buildings, trees or structures for features that may support bats.
If bat roost potential is identified, the next stage may involve bat emergence and re-entry surveys (BERS). These surveys confirm whether bats are present. They also show how bats use the site. This helps assess whether the proposed development could affect them.
Where impacts are likely, mitigation or licensing support may be required. This helps ensure bats and their roosts remain protected during works.
This staged approach helps homeowners, architects, planning consultants and developers understand what evidence is needed. It can also help avoid avoidable delays. Planning authorities then receive clear, proportionate information relevant to the scale of development.
Preliminary Roost Assessment (PRA)
During the assessment, a qualified ecologist inspects buildings, trees or structures for features that could support bats. These may include roof voids, gaps in brickwork, lifted tiles and soffits. They may also include cavities, splits, loose bark or other sheltered roosting opportunities.
Where a site has negligible or low bat roost potential, no additional surveys may be needed. Precautionary working methods may still be recommended where appropriate.
If moderate or high bat roost potential is identified, further survey work may be required. This is usually completed during the bat survey season. It helps confirm presence or likely absence.
This stage is often referred to as a bat scoping survey or phase 1 bat survey. It establishes the baseline ecological risk. It also helps planning authorities understand whether proposed works could affect bats or their roosts.
A clear PRA report supports proportionate decision-making. It helps homeowners, architects, planning consultants and developers avoid unnecessary delays.
Bat Emergence and Re-entry Surveys (BERS)
Where moderate or high bat roost potential is identified, bat emergence surveys or re-entry surveys may be required. These surveys are undertaken during the active bat season. They confirm presence, behaviour and species identification. They also help establish whether bats use buildings, trees or structures as roosts.
Bat emergence surveys usually take place at dusk. This is when bats may leave a roost to forage. Re-entry surveys are completed at dawn. This is when bats may return to the roost. The number of visits required depends on bat roost potential, site complexity and recognised survey guidance.
Ecologists use a combination of bat survey techniques. These include static and handheld acoustic detectors, passive acoustic monitoring and visual observation at dusk and dawn. These methods help record bat activity, flight lines and access points. They may also support species identification where possible.
The results provide robust evidence to support planning decisions. They also inform mitigation strategies where necessary. If bats are confirmed, the findings help determine whether timing controls are required. They may also identify design changes, roost retention, replacement roost features or licensing support before works proceed.
Mitigation and Licensing Support
Where bats are confirmed during survey work, ecologists may recommend mitigation measures to ensure development does not negatively affect protected species and complies with relevant legislation. Mitigation measures can include:
- Timing of works to avoid disturbance
- Retention of roost features where possible
- Installation of bat boxes or alternative roosting habitat
Mitigation strategies are designed based on survey findings and site conditions, ensuring impacts are avoided or reduced where possible. The type and extent of mitigation required will depend on factors such as the bat species present, the importance of the roost, how bats use the site and the nature of the proposed development. In many cases, practical measures can be incorporated into project designs at an early stage, helping to reduce ecological impacts while supporting planning objectives.
In some cases, a protected species licence may be required before works proceed, particularly where roosts could be affected. Ecologists can provide guidance throughout the licensing process, including preparation of supporting information, mitigation proposals and recommendations informed by survey results.
These measures help support habitat preservation, maintain bat populations and allow development works to proceed while maintaining appropriate ecological safeguards and compliance with planning requirements. They also contribute to wider wildlife conservation strategies, bat habitat protection and the long-term sustainability of local biodiversity, ensuring ecological considerations are integrated into development projects in a proportionate and practical way.
Reporting and Planning Submission
Following completion of a preliminary roost assessment, the findings are compiled into a professional report suitable for planning submission. The report explains the bat roost survey results, ecological context and whether bats are likely to be affected by development. It also sets out the inspection methods used, the features assessed and the reasoning behind the level of bat roost potential identified.
This report allows local planning authorities across England, planning consultants and architects to understand ecological constraints and make informed decisions. It can support planning applications, discharge of planning conditions or early design decisions where protected species may be a consideration. By presenting findings clearly, the report helps project teams respond to ecological requirements before they become a cause of delay.
Where no bats are present, or where the site is assessed as having negligible bat roost potential, this can help planning applications proceed without further ecological requirements, subject to local authority review. Where bats are present, or where further evidence is required, the report provides clear recommendations to support planning. This may include bat emergence surveys, timing considerations, mitigation measures or licensing support where roosts could be affected.
Bat Survey Season & Timelines
One of the most important considerations when planning a bat survey is timing. While a preliminary roost assessment can be carried out throughout the year, bat activity surveys are seasonal.
Bat emergence and re-entry surveys are typically undertaken between May and September when bats are active. Outside of this period, it is not possible to gather reliable activity data.This has practical implications for project timelines. If a PRA identifies the need for follow-up surveys, there may be delays if the survey season has passed.
Early commissioning of a preliminary roost assessment allows sufficient time to plan and complete any required surveys within the appropriate window. This is particularly important for projects with fixed deadlines or planning constraints.
Need a Preliminary Roost Assessment for Planning?
Bat survey requirements can vary depending on your property, location and development type. Our experienced ecologists can review your proposal, assess bat roost potential, and confirm whether a preliminary roost assessment or further surveys are required before you submit your planning application.
Costs and Timescales
The cost of a preliminary roost assessment varies depending on site-specific factors. While smaller, straightforward sites may require only a single visit, more complex sites may involve additional time for inspection and reporting.
Key cost drivers include:
- Size and scale of the development site
- Number and type of buildings or trees
- Accessibility and safety considerations
- Level of detail required for planning submission
Timescales are typically short, with surveys often completed within a day and reports issued within a few working days. However, where additional survey work is required, project timelines may extend depending on survey season constraints.
Local Planning Policy & Considerations
While bat survey requirements are guided by national legislation and policy, local planning authorities across England may apply their own validation requirements and ecological expectations.
Many councils require ecological information, including a preliminary roost assessment, where development could affect biodiversity. This is often set out within local validation checklists or planning guidance documents.
For example:
- Urban authorities may place emphasis on impacts to existing buildings and green infrastructure
- Rural authorities may focus on agricultural buildings, hedgerows and woodland edges
- Areas with designated landscapes or conservation areas may require more detailed ecological consideration
In addition, biodiversity net gain requirements and broader ecological policies may influence how bat surveys are integrated into planning applications.
Engaging with a qualified ecologist early in the process helps ensure that local policy expectations are understood and addressed appropriately.
Local Context Across England
Across England, the need for a preliminary roost assessment is shaped by a wide range of environmental and built characteristics. The country’s varied landscape from dense urban centres to rural farmland creates diverse conditions that can support bat populations and influence planning requirements.
Older buildings in cities such as London, Manchester and Bristol often contain features such as roof voids, crevices, gaps beneath tiles, soffits, brickwork openings and traditional construction materials that can provide suitable roosting opportunities. These features are commonly reviewed during a PRA bat survey, particularly where projects involve roof works, loft conversions, demolition or refurbishment.
In contrast, rural areas across counties such as Dorset, Hampshire and Derbyshire frequently include barns, farm buildings, churches, listed buildings, mature trees and agricultural structures, all of which are commonly associated with bat roost potential. These sites may also sit close to hedgerows, pasture, woodland edge or watercourses, increasing their value for commuting and foraging bats.
River corridors such as the Thames, Severn and Trent, along with woodland edges and hedgerow networks, provide important commuting and foraging routes. Parks, gardens, canals, wetlands, reservoirs and railway corridors can also contribute to habitat connectivity in both urban and rural settings.
These landscape features are often considered during habitat suitability assessment and can influence whether further survey work is required. A preliminary roost assessment helps identify how local buildings, trees and surrounding habitats may interact with the proposed development, supporting proportionate recommendations and planning-ready ecological reporting across England.
What You Receive From Your PRA Bat Survey
Your preliminary roost assessment includes a comprehensive, planning-ready ecological report suitable for planning submission and to support planning applications or discharge of planning conditions where required. The report is structured clearly so it can be reviewed efficiently by planning officers, ecological consultees, architects and project teams across England, ensuring alignment with national guidance and local authority expectations.
This report includes detailed site information and survey findings. Typical contents include:
- Site description and development overview – outlining the property, building type and surrounding habitat context, including features such as rivers, woodland edges, hedgerows or urban green corridors that may influence bat roost potential and bat activity.
- Detailed survey methodology – explaining how the ecological site assessment was undertaken, including access, inspection methods and recognised bat survey techniques used in accordance with guidance.
- Assessment of bat roost potential – identifying features within buildings or trees that may support bats and explaining the reasoning behind the assessment.
- Habitat suitability assessment and biodiversity context – considering how the site fits within the wider landscape and potential commuting or foraging routes.
- Findings from the ecological site assessment and environmental impact analysis where relevant.
- Clear conclusions and risk categorisation with recommendations for further surveys or mitigation, alongside guidance on next steps within the planning process.
The preliminary bat roost assessment report provides clarity and confidence for all parties involved in the project.
Local Coverage
ACP Consultants supports projects across England including London, Birmingham, Manchester, Leeds, Bristol, Nottingham, Sheffield, Cambridge, Oxford and Newcastle. Our nationwide coverage allows us to assist homeowners, architects, planning consultants and developers across a wide range of urban, suburban and rural environments where bat surveys and preliminary roost assessments may be required for planning.
These locations include a diverse mix of property types and habitats that can influence bat roost potential and habitat suitability assessment outcomes. In cities such as London, Manchester and Birmingham, older buildings, roof voids and redevelopment sites frequently require ecological site assessment as part of the planning process. In locations such as Cambridge, Oxford and Bristol, historic buildings, mature trees, rivers and green corridors can provide suitable conditions for bats and may increase the likelihood of survey requirements.
Across Nottingham, Sheffield, Leeds and Newcastle, residential extensions, demolition projects, infrastructure upgrades and lighting schemes commonly require preliminary bat roost assessment work where protected species could be affected. Our experience across varied landscapes and development types helps ensure that surveys, environmental impact analysis and planning-ready reports are proportionate, clear and aligned with recognised ecological guidance.
Common Project Types in This Area
Across these locations, typical developments that may require a preliminary roost assessment include barn conversions and rural redevelopment, residential extensions, loft conversions and roof works, demolition of older buildings or structures, tree removal or management linked to development, infrastructure upgrades and lighting schemes, and redevelopment of commercial or industrial sites.
These project types often intersect with habitats or structures capable of supporting bats, making early ecological assessment important. For example, barn conversions and rural redevelopment can involve traditional buildings, roof voids, timber framing, stonework, nearby hedgerows, farmland or woodland edge habitat. Residential extensions, loft conversions and roof works may affect gaps beneath tiles, soffits, fascias or roof spaces where bats could roost.
Demolition of older buildings or structures can also trigger the need for a PRA bat survey, particularly where buildings have cracks, crevices or sheltered access points. Tree removal or management linked to development may require assessment where mature trees contain cavities, splits, loose bark or other potential roost features.
Infrastructure upgrades and lighting schemes may affect bat commuting routes or foraging habitat, especially near rivers, canals, parks, gardens, woodland, hedgerows or green corridors. Redevelopment of commercial or industrial sites may also require a bat roost assessment where older buildings, boundary trees or nearby habitats create potential ecological constraints. Early assessment helps identify survey requirements, planning risks and next steps before delays arise.
Why Choose ACP Consultants Ltd
ACP Consultants Ltd provides bat surveys in England with a strong focus on planning-led ecological support, helping clients navigate ecological requirements efficiently and with confidence.
Our team of experienced ecologists works in line with recognised standards and guidance, ensuring that all reports are suitable for planning submission and review. We understand how ecological surveys fit within the wider planning process and aim to provide clear, proportionate advice that supports timely decision-making without unnecessary delay.
We support a wide range of clients, including homeowners, architects, planning consultants and developers, and tailor our approach to suit each project, from small residential works to larger multi-phase developments.
Our experience across diverse site types allows us to identify potential ecological constraints early and provide practical recommendations aligned with planning expectations.
Our approach is based on:
- Technical competence and professional standards (CIEEM-aligned), ensuring surveys follow recognised ecological best practice
- Clear, structured reporting designed for planning officers and consultees
- Nationwide coverage across England, supporting projects in both urban and rural locations
- Consistent quality assurance processes to maintain accuracy and reliability
- Experience supporting planning applications across varied site types, ensuring reports are relevant and proportionate
References and Useful Resources
- Chartered Institute of Ecology and Environmental Management (CIEEM) – Bat Survey Guidelines for UK Homeowners
- CIEEM – What to Expect from a Bat Survey: Homeowner guide to survey stages, reporting and outcomes
- CIEEM – Bat Mitigation Guidelines (2025): Best practice guidance for mitigation design and implementation
- GOV.UK – Bats: Advice for Making Planning Decisions
- GOV.UK – Bats: Protection, Surveys and Licences
- GOV.UK – Protected Species: How to Review Planning Applications: Guidance for assessing ecological impacts within planning decisions
- Natural England – Bat Advice Service (BAS) Updates and Guidance
- Bat Conservation Trust – British Bat Survey (Passive Acoustic Surveys)
- Bat Conservation Trust – Contacting an Ecological Consultant: Advice on engaging a qualified bat ecologist for surveys and planning
- Bat Conservation Trust – Planning and the Law: Overview of legal protections and planning considerations for bats
- Bat Conservation Trust – Building or Development Works: Guidance on managing bats during construction and development
- Bat Conservation Trust – Planning and Infrastructure Act: Policy context affecting biodiversity and development
- Bat Conservation Trust – Planning and Infrastructure Policy Update (2026): Latest developments in planning and biodiversity policy
- Bat Conservation Trust – National Bat Monitoring Programme Surveys
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Frequently Asked Questions
A preliminary roost assessment (PRA) bat survey is the first stage of ecological assessment required for many planning applications in England. It identifies whether buildings, trees or structures have the potential to support bats and determines if further surveys, such as bat emergence or activity surveys, are needed. As bats are legally protected, planning authorities require this information to assess development impacts and ensure compliance. The process supports early-stage planning, helping avoid delays and providing clear, planning-ready ecological reports aligned with national guidance.
What is a preliminary roost assessment?
A preliminary roost assessment is a daytime ecological survey used to determine whether buildings or trees have the potential to support bats. It forms the first stage of the bat survey process and is sometimes referred to as a PRA bat survey, bat scoping survey or phase 1 bat survey.
Do I need a preliminary roost assessment for planning permission?
Planning authorities may require a preliminary roost assessment where development could affect structures or habitats capable of supporting bats. This ensures decisions are based on sufficient ecological information and aligns with protected species legislation.
When should a PRA bat survey be carried out?
A PRA bat survey can be undertaken at any time of year, making it suitable for early-stage planning. However, if further surveys such as a bat activity survey are required, these may need to be carried out during the bat survey season.
What happens if bats are found during a PRA?
If evidence of bats or suitable roost features is identified, further surveys such as bat emergence surveys or bat activity surveys may be recommended to confirm presence, behaviour and species identification.
What is included in a preliminary roost assessment report?
A preliminary roost assessment report includes site details, survey findings, habitat suitability assessment, ecological site assessment results and environmental impact analysis where relevant. A preliminary bat roost assessment report also provides clear recommendations and next steps to support planning applications.
What is the difference between a PRA and a bat activity survey?
A PRA assesses the potential for bats to be present, while a bat activity survey records actual bat presence and behaviour using techniques such as passive acoustic monitoring and observation.
What bat survey techniques are used during a PRA?
A preliminary roost assessment uses non-intrusive bat survey techniques including visual inspection, evidence recording and habitat assessment. Where required, further surveys may involve passive acoustic monitoring and activity surveys.
Does a preliminary roost assessment include habitat suitability assessment?
Yes. A preliminary roost assessment includes a habitat suitability assessment, which evaluates whether the surrounding environment provides suitable commuting routes or foraging habitat for bats.
How much does a preliminary roost assessment cost and how long does it take?
The cost of a preliminary roost assessment depends on site size, complexity and location. Most surveys are completed within a few hours, with reports typically issued within a few working days. A tailored quote provides the most accurate estimate.
Can I get a preliminary roost assessment near me?
Yes. Preliminary roost assessment services are available nationwide, including locations such as London, Essex, Hampshire and across England, depending on project requirements.
Are preliminary roost assessment guidelines followed?
Yes. Surveys are carried out in accordance with recognised preliminary roost assessment guidelines, including guidance from Natural England and the Bat Conservation Trust, ensuring consistency and reliability.
How long is a preliminary roost assessment valid?
Ecological reports are typically valid for a limited period, often around 1–2 years, depending on site conditions, planning requirements and guidance. Updated surveys may be required if conditions change.
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- Last Updated:
- October 2026
Disclaimer: Our content is prepared by ACP Consultants’ in-house specialists and is based on current guidance, standards, and best practice in environmental consultancy. While we make every effort to keep information accurate and up to date, it is provided for general guidance only and should not be relied upon as a substitute for professional advice on specific projects. Planning authorities retain final decision-making powers, and requirements may vary between local authorities and over time. ACP Consultants accepts no liability for any loss arising from reliance on this content without obtaining tailored advice for your project.