Guide
Planning for medium sites (10-49 units)
How the new medium sites category (10-49 units) provides proportionate planning requirements for SME housebuilders. Covers proposed exemptions, simplified processes, and what this means for your development.
The planning system has historically treated development as either "minor" (1-9 units) or "major" (10+ units), with major development facing significantly more onerous requirements regardless of whether it's 10 homes or 1,000.
Government reforms recognise this burden falls disproportionately on SME housebuilders. A new medium sites category (10-49 units) is being introduced to provide proportionate requirements that reflect the actual scale and impact of development.
This guide explains what the medium sites category means for developers and what proportionate requirements to expect.
Current thresholds and their problems
Why the current system fails SMEs
The 10-unit threshold creates a cliff edge where requirements jump dramatically:
- Determination period: 8 weeks (minor) vs 13 weeks (major)
- Committee decisions: Minor typically delegated; major often goes to committee
- Supporting documents: Major development requires extensive documentation
- S106 obligations: Affordable housing and infrastructure contributions typically kick in at 10 units
- EIA screening: Projects of 10+ units may require environmental impact assessment screening
A 10-unit scheme bears the same procedural burden as a 500-unit scheme, but has far less scale to absorb the costs.
The medium sites category
The new medium sites category (10-49 units, or 0.5-2 hectares) creates a middle tier with proportionate requirements:
Proposed medium sites easements
- Faster determination: Target decision period between minor and major timescales
- Delegated decisions: More medium applications determined by officers rather than committee
- Proportionate documentation: Simpler transport statements, scaled design statements
- S106 proportionality: Contributions proportionate to development impact
- Building Safety Levy exemption: Proposed exemption from the new levy for medium sites
- Streamlined consultation: Focused consultation appropriate to development scale
Building Safety Levy exemption
The Building Safety Levy, coming into force Autumn 2026, will charge developers per dwelling to fund remediation of historical building safety defects. However, medium sites (10-49 units) are proposed to be exempt.
This exemption recognises that:
- SME housebuilders didn't create the historical defects being remediated
- The levy would disproportionately impact smaller builders' viability
- SME housebuilders building sub-50 unit schemes are rarely involved in high-rise construction
Note: This exemption is proposed but not yet confirmed. Monitor government announcements for the final levy structure.
What this means for your development
If your scheme is 10-49 units
You're in the sweet spot for medium sites benefits:
- Large enough to achieve economies of scale on construction
- Small enough to potentially benefit from medium sites easements
- Below typical local plan major infrastructure contribution thresholds
- Proposed Building Safety Levy exemption
If your scheme is 50+ units
Full major development requirements apply. Consider whether the scheme could be viably delivered in phases of under 50 units - though be aware LPAs may treat phased applications as a single development.
Strategic considerations
When appraising land, consider the threshold effects:
- 9 vs 10 units: Staying under 10 units keeps you in minor category with faster determination
- 49 vs 50 units: Staying under 50 units may qualify for medium sites benefits
- Don't artificially constrain: If the site can viably support 12 units, building 9 to avoid thresholds may not be the best commercial decision
Current planning process for 10-49 unit schemes
Until medium sites easements are fully implemented, schemes of 10-49 units currently face major development requirements. Here's what to expect:
Determination period
13 weeks statutory timescale (16 weeks if EIA applies). In practice, many LPAs exceed this. You can agree extensions of time or appeal for non-determination.
Required documents
Typical documentation for a 10-49 unit scheme:
- Planning Statement
- Design and Access Statement
- Transport Statement (not full Transport Assessment in most cases)
- Flood Risk Assessment (if in flood zone or over 1 hectare)
- Ecological surveys and Biodiversity Gain Plan
- Tree survey and arboricultural impact assessment
- Nutrient Neutrality Statement (if in affected catchment)
Section 106 considerations
At 10+ units, you're typically liable for:
- Affordable housing: Usually 10-40% depending on local plan policy and viability
- Education contributions: Per-dwelling contributions based on pupil yield
- Open space: On-site provision or financial contribution
- Highways: Any required off-site works
However, contributions should be proportionate. A 15-unit scheme shouldn't bear the same contribution as a 150-unit scheme.
Making the case for proportionality
Until medium sites easements are formally implemented, you can still argue for proportionate treatment:
In pre-application discussions
- Highlight government policy direction on medium sites
- Reference the disproportionate burden on SME housebuilders
- Propose scaled-down documentation appropriate to your scheme's impact
- Discuss proportionate S106 based on actual site impacts
In viability discussions
- Demonstrate that full major development costs undermine scheme viability
- Show that proportionate requirements would enable delivery
- Propose alternatives that achieve policy objectives at lower cost
If requirements seem disproportionate
- Challenge whether S106 contributions meet the three tests
- Question whether documentation requirements are genuinely necessary
- Consider whether appeal might achieve a more proportionate outcome
SME housebuilders: Medium sites reforms work in your favour
The medium sites category is specifically designed to support SME housebuilders. Government recognises that:
- SME housebuilder market share has declined from 40% (1980s) to ~10%
- 93% of SME housebuilders cite planning as their major barrier
- Current thresholds treat a 15-unit scheme the same as a 500-unit scheme
- Proportionate requirements could unlock significant SME housing delivery
Strategic positioning: Build expertise in medium site development. As easements are implemented, SME builders positioned in this segment will benefit most from streamlined processes.
Timeline for medium sites reforms
Medium sites easements are being implemented progressively:
- Policy direction: Established in DLUHC planning reform working papers
- NPPF updates: May incorporate proportionate approach guidance
- Building Safety Levy: Exemption for medium sites when levy commences (Autumn 2026)
- Regulatory changes: May require secondary legislation for formal threshold changes
In the interim, LPAs have discretion to apply proportionate approaches. Pre-application engagement that references government policy direction may achieve proportionate treatment even before formal changes.