Planning for medium sites (10-49 units)

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: Schedule 2 screening thresholds for urban development (site over 5 hectares, more than 150 dwellings, or over 1 hectare of non-residential floorspace - or any size in a sensitive area) can catch larger schemes

A 10-unit scheme bears the same procedural burden as a 500-unit scheme, but has far less scale to absorb the costs.

The proposed medium sites category

The proposed medium sites category (10-49 homes - with a site-size parameter that has evolved through consultation, most recently up to 2.5 hectares) would create 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 relief: Explored in the working paper, but not included in the levy regulations as made (see below)
• Streamlined consultation: Focused consultation appropriate to development scale

Building Safety Levy: where medium sites stand

The Building Safety Levy comes into force in England on 1 October 2026. It is charged per square metre of chargeable floorspace (not per dwelling), at rates set for each local authority area, with a 50% discounted rate for previously developed land. It funds remediation of historical building safety defects.

Medium sites are not exempt. An exemption for 10-49 unit schemes was explored alongside the site-thresholds working paper, but the regulations as made exempt only developments of fewer than 10 dwellings (or fewer than 30 bedspaces for purpose-built student accommodation), plus other exclusions such as affordable housing. Note that a sub-10 building control application that forms part of a wider major residential planning permission still incurs the levy.

Budget for the levy in any 10+ unit scheme appraisal: it is payable before the completion certificate is issued (or first occupation).

What this means for your development

If your scheme is 10-49 units

Under current law your scheme is major development, but you would be in the sweet spot if the medium sites reforms are implemented:

• Large enough to achieve economies of scale on construction
• Small enough to potentially benefit from medium sites easements if introduced
• Below typical local plan major infrastructure contribution thresholds
• But note: the Building Safety Levy applies from 1 October 2026 (only sub-10 dwelling schemes are exempt)

If your scheme is 50+ units

Full major development requirements apply and would continue to apply under the proposed reforms. 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 if the reforms are implemented
• 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

Timeline for medium sites reforms

The medium sites proposals have not yet been implemented. Where things stand:

• Policy direction: Established in the MHCLG planning reform working paper on site thresholds (May 2025)
• NPPF updates: May incorporate proportionate approach guidance
• Building Safety Levy: Commences 1 October 2026 with no medium-sites exemption (only sub-10 dwelling developments are exempt)
• Regulatory changes: Formal threshold changes will require secondary legislation; none has been made yet

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.