How To Expertly Navigate the Hertfordshire Green Belt Now

The Hertfordshire Green Belt is a critical area of protected land surrounding urban areas, designed to prevent urban sprawl and preserve the county’s countryside. Covering approximately 13% of England’s land, the Green Belt imposes strict regulations on development, but opportunities for house extensions, permitted development, and new builds still exist, particularly with the introduction of the “grey belt” concept in 2024. As an architectural practice, we understand the complexities of planning in the Hertfordshire Green Belt and are here to guide you through the possibilities, drawing on the latest National Planning Policy Framework (NPPF) and local policies.

Understanding the Hertfordshire Green Belt

What is the Hertfordshire Green Belt?

The Hertfordshire Green Belt serves five key purposes, as outlined in the NPPF: preventing urban sprawl, stopping towns from merging, safeguarding the countryside, preserving historic town settings, and encouraging urban land recycling. In Hertfordshire, this protected land surrounds towns like St Albans, Hertford, and Sawbridgeworth, making development a sensitive issue. However, the Hertfordshire Green Belt is not a blanket ban on building. Exceptions and permitted development rights allow for certain projects, provided they align with strict criteria to maintain the area’s openness and character. For detailed planning guidance, East Hertfordshire County Council’s planning services offers valuable resources for homeowners.

The New Grey Belt Concept

In 2024, the UK government introduced the concept of “grey belt” land within the Green Belt, defined as previously developed land or areas that make a limited contribution to the Green Belt’s five purposes. This shift, detailed in the updated NPPF, aims to address the housing crisis by allowing more flexibility for development on low-quality Green Belt land. In the Hertfordshire Green Belt, local authorities are now required to review their Green Belt boundaries and identify grey belt sites, prioritising brownfield land first, then grey belt, before considering other Green Belt areas. The Campaign to Protect Rural England (CPRE) notes that grey belt developments must meet sustainability and affordability criteria, such as the “Golden Rules” requiring 50% affordable housing on ex-Green Belt land.

House Extensions in the Hertfordshire Green Belt

Permitted Development Rights for Extensions

Homeowners in the Hertfordshire Green Belt can often extend their properties without full planning permission under permitted development (PD) rights, provided they adhere to specific guidelines. These rights allow for:

• Single-storey extensions: Up to 4 meters in depth for detached houses or 3 meters for semi-detached/terraced homes, with a maximum height of 4 meters.
• Two-storey extensions: Allowed if they don’t exceed 3 meters in depth and are at least 7 meters from the rear boundary.
• Side extensions: Limited to half the width of the original house and a maximum height of 4 meters.
• Roof extensions: Permitted if they don’t increase the roof height significantly or alter the property’s openness.

 

However, PD rights in the Hertfordshire Green Belt come with caveats. Local authorities, such as St Albans City and District Council, may impose Article 4 Directions, restricting PD rights in specific areas like conservation zones. Additionally, listed buildings or properties in Areas of Outstanding Natural Beauty (AONB) face stricter rules. Homeowners should always check their property’s planning history, as PD rights may have been removed during previous approvals.

Planning Permission for Larger Extensions

For extensions exceeding PD limits, planning permission is required. The NPPF allows extensions in the Hertfordshire Green Belt if they are not “disproportionate” to the original building, typically meaning a volume increase of 30-40%, though some councils may cap this lower. High-quality architectural design is crucial to demonstrate that the extension preserves the Green Belt’s openness, as outlined in the GOV.UK Green Belt guidance. For example, a recent project in Hertfordshire’s Conservation Area, “The Bothy,” successfully used PD rights as a fallback argument to secure planning consent.

New Builds in the Hertfordshire Green Belt

Exceptions for New Builds

Constructing new homes in the Hertfordshire Green Belt is challenging but possible under specific NPPF exceptions, including:

• Replacement dwellings: New buildings can replace existing ones if they are in the same use and not materially larger.
• Limited infilling: Building on small gaps within villages or redeveloping brownfield sites, provided it doesn’t harm the Green Belt’s openness.
• Affordable housing: Small-scale developments for local community needs, as seen in South Oxfordshire’s 2021 approval of 12 affordable homes.
• Agricultural conversions: Class Q of the General Permitted Development Order allows converting agricultural buildings into up to three dwellings (max 450m²), subject to prior approval.

 

The grey belt policy further enhances opportunities for new builds. In Hertfordshire, grey belt sites – such as disused car parks or low-value land – can be developed if they meet sustainability criteria. The Planning Portal provides detailed guidance on navigating these exceptions for Green Belt development.

Case Study: Subterranean Dwelling Appeal

In 2023, a planning appeal in Hertfordshire secured permission for a subterranean dwelling in the Green Belt. The Plainview Planning team argued that the underground design minimised impact on openness, leveraging the lack of a five-year housing land supply and existing permissions. This case highlights how innovative design can unlock development potential in the Hertfordshire Green Belt, as noted in Urbanist Architecture’s guide to Green Belt exceptions.

Navigating the Planning Process

Working with Local Authorities

Hertfordshire’s local planning authorities (LPAs), such as East Hertfordshire Council, play a pivotal role in assessing Green Belt proposals. Homeowners and developers must submit detailed applications addressing Green Belt purposes, sustainability, and community benefits. A lawful development certificate is recommended for PD projects to confirm compliance and reassure future buyers.

The Role of Architectural Designers

As an architectural practice, we emphasise the importance of professional guidance. Experienced architectural designers, such as ourselves, can navigate Hertfordshire Green Belt regulations, identify grey belt opportunities, and design proposals that blend with the natural surroundings. Our feasibility studies, including ecological and topographical surveys, ensure compliance with NPPF and local policies, maximising approval chances. The Royal Institute of British Architects (RIBA) highlights the value of architectural expertise in securing planning consent for Green Belt projects.

Conclusion

The Hertfordshire Green Belt remains a complex but navigable landscape for development. With permitted development rights, strategic planning, and the new grey belt framework, homeowners can extend their properties, and developers can explore new builds. By partnering with skilled architectural designers and staying informed about NPPF updates, you can unlock the potential of your Hertfordshire Green Belt project while preserving the area’s cherished openness. Contact us to explore your project in the Hertfordshire Green Belt.