Horsham BNG advice
Biodiversity Net Gain in Horsham
Plan your Horsham development around local habitats, planning requirements and practical biodiversity gains.
ACP Consultants can help with habitat surveys, biodiversity metric calculations and a practical BNG delivery plan for your Horsham site.
Local requirements
Horsham BNG requirements at a glance
| Check | Practical answer |
|---|---|
| Planning authority | Horsham District Council / South Downs National Park Authority where mapped — verify the actual parcel, any special planning jurisdiction and site type |
| Adopted development plan | Horsham District Planning Framework (HDPF) adopted 27 November 2015 |
| Specific biodiversity policies | Policy 31 – Green Infrastructure and Biodiversity |
| Emerging plan status | Two different future-plan processes must not be conflated. The Horsham District Local Plan 2023–2040 remains under examination, with further hearings in October 2026 and adoption anticipated in early 2027. Separately, 'Horsham District 2045' was scheduled to start under new 2026 plan-making regulations around 1 November 2026. Neither is yet adopted. |
| LNRS | West Sussex Local Nature Recovery Strategy, Published 24 June 2026; West Sussex County Council |
| Statutory BNG | Normally at least 10% for eligible applications; exemption and application date checks are essential |
| Protected sites | Independent Habitats Regulations or protected-species evidence where a credible impact pathway exists |
Planning authority and policy
Local planning requirements for Horsham
Confirm the planning authority
Horsham District Council handles applications outside the South Downs National Park. For mapped Park land, check the National Park Authority’s policies and decision arrangements.
See BNG in West Sussex and the South East regional guide.
Use the adopted development plan
Horsham District Planning Framework (HDPF) adopted 27 November 2015. Relevant policies include Policy 31 – Green Infrastructure and Biodiversity.
The 2023–2040 plan remains under examination following October 2026 hearings. Horsham District 2045 is a separate emerging process. Neither has replaced the adopted 2015 framework.
Establish the gain target
Eligible development normally needs at least 10% statutory gain. Establish the applicable target using current national policy, any relevant site-allocation policy and existing permission.
Plan habitat retention, suitable enhancement and long-term management alongside the site layout. Check the national biodiversity planning policies when establishing obligations.
Check dates and exemptions
For applications from 6 August 2026, sites up to 0.2 hectares may qualify for an exemption if no onsite priority habitat is adversely affected.
Householder, de minimis, temporary-development and transitional rules have their own conditions. Record the application date, site area and supporting habitat evidence.
Use the BNG exemptions guide to identify the relevant route.
Nature recovery and local geography
Local habitats and nature recovery in Horsham
Use the local nature recovery map
The published West Sussex Local Nature Recovery Strategy provides priorities and mapped opportunities for habitat recovery. It was published on 24 June 2026.
For Horsham, consider Arun and Adur floodplains, High Weald woodland, urban-fringe habitats and downland edges. Match the actual site location and proposed habitat to a relevant recovery measure.
Local habitats to consider in Horsham
Use the landscape context to scope the survey, then record the habitats actually present within the site boundary.
| Local setting | Potential habitat or evidence issue |
|---|---|
| Arun and Adur floodplains | Floodplain grassland, ditches and wetland habitat, with site-specific river and HRA screening where needed. |
| Wooded High Weald parts | Ancient woodland, hedgerows, wooded valleys and connected habitats, often sensitive to clearance and disturbance. |
| Horsham urban fringe and new housing sites | Trees, ditches, scrub and managed greenspaces should be assessed before layout commitments. |
| South Downs National Park southern edge | Chalk or downland habitats and Park LPA restrictions where the parcel is actually within the Park. |
Plan protected-site and species evidence
Floodplain proposals may affect ditches, river corridors and wetland habitats. Establish any credible protected-site or hydrological pathway before setting the survey and drainage scope.
Ancient woodland, mature trees and hedgerow networks can constrain High Weald and urban-fringe sites. Check National Park jurisdiction and relevant downland habitats for southern parcels.
Planning and delivery
Preparing evidence and delivering biodiversity gain
Prepare the habitat baseline and metric
Start with the site’s habitat baseline and condition. Use the appropriate statutory metric; the Small Sites Metric is suitable only where its eligibility conditions are met.
In Horsham, survey Arun and Adur floodplains, High Weald woodland, urban-fringe habitats and downland edges where these occur within or affect the proposal. Record the actual habitat condition and relevant watercourse evidence.
See BNG assessments and habitat surveys, habitat condition assessment and Small Sites Metric assessments.
Prepare the planning submission
Confirm the planning authority, application date, relevant policies and whether statutory BNG applies. Then agree a proportionate submission scope with the council.
- An applicability or exemption explanation supported by site evidence.
- The red-line boundary, baseline habitat plan and metric where required.
- Proposed layout, retained habitats and feasible habitat gains.
- Any protected-species, watercourse, drainage or Habitats Regulations evidence.
Test the layout against local habitat constraints
Retain sensitive habitats and useful connections where possible. Use these questions to compare realistic layout and habitat options.
| Local setting to test | Useful design and survey question |
|---|---|
| Arun and Adur floodplains | Can the proposal avoid impacts? Floodplain grassland, ditches and wetland habitat, with site-specific river and HRA screening where needed. |
| Wooded High Weald parts | What would retaining or improving connectivity involve? Ancient woodland, hedgerows, wooded valleys and connected habitats, often sensitive to clearance and disturbance. |
| Horsham urban fringe and new housing sites | Do the existing habitats or species interests restrict the proposed gain type? Trees, ditches, scrub and managed greenspaces should be assessed before layout commitments. |
| South Downs National Park southern edge | Can the layout integrate useful green infrastructure? Chalk or downland habitats and Park LPA restrictions where the parcel is actually within the Park. |
Choose habitats suited to the site and its long-term management. Match nature recovery measures to the published LNRS map, then calculate all relevant unit categories.
Development and regeneration context
The emerging plan’s growth proposals need to be distinguished from adopted allocations and existing permissions. For a Horsham urban-fringe site, map woodland edges, ditches and hedgerows before locating buildings or committing habitat areas to drainage or recreation.
A practical Horsham planning example
Illustration: an urban-fringe scheme contains hedges, grassland and a wooded stream. Retain connected habitats where feasible, establish watercourse condition and identify realistic enhancement areas. Test the metric and management plan alongside flood and landscape requirements.
Plan off-site delivery and long-term management
Calculate the genuine shortfall before committing to off-site units. Apply the relevant gain hierarchy, habitat trading rules and location requirements to the proposed delivery route.
Use the West Sussex Local Nature Recovery Strategy to explore habitat opportunities. Confirm registration, suitable units and current availability directly with the proposed supplier.
Read about off-site biodiversity units, Biodiversity Gain Plans and Habitat Management and Monitoring Plans.
Council and delivery costs
What should your Horsham BNG budget cover?
Budget for habitat surveys, metric calculations, planning reports and any gain-plan or management work. The scope depends on the site, habitat types and planning stage.
Woodland, river and species surveys can need different seasons and specialist inputs. Identify any off-site habitat purchase, legal work and monitoring separately from the initial ecology and metric assessment.
Planning evidence
Horsham BNG preparation checklist
Free resource: Use the local BNG planning evidence route worksheet. It provides a light, accessible reference to official documents and the difference between BNG and separate ecological duties.
Planning evidence worksheet
Find your Horsham planning and evidence route
Use these questions to organise the planning, habitat and delivery information for your site.
Which authority and adopted plan apply?
Horsham District Council handles applications outside the South Downs National Park. For mapped Park land, check the National Park Authority’s policies and decision arrangements.
Horsham District Planning Framework (HDPF) adopted 27 November 2015. Relevant policies include Policy 31 – Green Infrastructure and Biodiversity.
How should I treat emerging policies?
The 2023–2040 plan remains under examination following October 2026 hearings. Horsham District 2045 is a separate emerging process. Neither has replaced the adopted 2015 framework.
Establish the applicable gain target using current national policy, any relevant up-to-date site-allocation policy and existing permission.
How do I use the nature recovery map?
Match the actual site and proposed habitat to a relevant measure in the West Sussex Local Nature Recovery Strategy. Record the map and survey evidence supporting the metric entry.
Could an exemption apply?
For applications from 6 August 2026, sites up to 0.2 hectares may qualify if no onsite priority habitat is adversely affected. Other exemptions and transitional provisions have separate conditions. Record the development type, date, red-line area and habitat evidence.
Which separate ecological issues matter?
Floodplain proposals may affect ditches, river corridors and wetland habitats. Establish any credible protected-site or hydrological pathway before setting the survey and drainage scope.
Ancient woodland, mature trees and hedgerow networks can constrain High Weald and urban-fringe sites. Check National Park jurisdiction and relevant downland habitats for southern parcels.
When is the final gain plan needed?
For eligible ordinary applications, the statutory Biodiversity Gain Plan is normally approved after permission and before development starts. Agree earlier planning evidence with the authority and identify feasible management and any off-site delivery route.
Details to gather before an enquiry
Project support
How ACP can help with your Horsham project
ACP can help scope the habitat surveys, metric calculations and planning reports needed for your Horsham proposal. Early advice is most useful while the layout can still change.
We can consider Arun and Adur floodplains, High Weald woodland, urban-fringe habitats and downland edges alongside the site’s planning route and proposed works.
Local planning questions
Frequently asked questions about BNG in Horsham
For a site-specific question, discuss your project with ACP.
Which plan is adopted for Horsham BNG in November 2026?
The Horsham District Planning Framework 2015 remains adopted. Its Policy 31 is relevant, alongside current national statutory BNG.
Is Horsham's 12% target already mandatory?
The higher target appears in emerging plan material. The adopted starting point is the 2015 framework and current statutory rules. Establish the applicable target from national policy, any relevant site allocation and existing permission.
Why are there two Horsham Local Plan programmes?
The submitted 2023–2040 plan is still being examined, while a new 2045 plan was also initiated under the reformed plan-making system. Neither is an adopted replacement at this date.
Does the South Downs National Park use Horsham's Local Plan?
Not for land within its statutory planning area. Confirm whether the site falls inside the National Park and check the Park Authority's current policies.
Which habitat surveys might a site in Horsham need?
Scope the assessment around the habitats and proposed effects. In Horsham, relevant settings include Arun and Adur floodplains, High Weald woodland, urban-fringe habitats and downland edges. The red-line plan, habitat condition and any water or species pathways determine the survey work.
How should I use the local nature recovery map?
Use the published map to match the site and proposed habitat to a recovery measure. Survey evidence and feasible management then support the design and metric calculation. Confirm the planning authority separately, including any National Park jurisdiction.
How do BNG exemptions work for a small Horsham development?
Since 6 August 2026, a red-line site of 0.2 hectares or less may qualify for exemption if the statutory conditions are satisfied, including no adverse effect on onsite priority habitat. Other ecological duties may remain.
How can habitat retention help with BNG in Horsham?
Retain valuable habitats and connections where feasible, and test how the layout affects them. If a genuine shortfall remains, use the applicable gain hierarchy and habitat trading rules to select a suitable delivery route.
When is the final gain plan needed in Horsham?
For eligible ordinary applications the final statutory Biodiversity Gain Plan normally needs approval after planning permission and before commencement. Check what the council asks for during validation and whether a management plan is needed.
Talk to ACP / Site enquiries
What does your site need next?
Tell us where the site is, what you plan to build and how far the application has progressed. We’ll use that context to discuss the surveys, calculations or plans your project needs.
What to have to handA red-line plan, an existing ecology report or a request from the council can help us scope the work. Start with whatever you already have.
Request a site-specific quotation
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Horsham BNG
Sources and references
Reviewed 10 November 2026.
Official planning and nature recovery sources
- Current GOV.UK exemption guidance
- West Sussex LNRS
- Appropriate assessment guidance
- Current Horsham District Planning Framework
- HDPF Policy 31 original
- BNG guide
- 2026–40 plan examination update
- Horsham 2045 new Local Plan
- GOV.UK's BNG guidance
- statutory biodiversity metric downloads
- National Planning Policy Framework: biodiversity policies N1 and N2