Planning Permission Secured to Support Enforcement Appeal - Hill Rise, Hertsmere.
A policy-led strategy combining permitted development, lawful fallback and full planning to unlock approval.
The scheme was approved by the Hertsmere Borough Council under reference 25/1296/HSE.
Project Overview
Planning permission has been secured for a rear infill extension at a residential property in Hertsmere, forming part of a wider strategy to regularise and rationalise existing development on site.
The approved scheme connects a previously established single-storey rear extension (approved under Prior Approval) with a replacement outbuilding secured under a Certificate of Lawful Development, alongside associated roof and terrace alterations.
This application was not submitted in isolation - it forms part of a coordinated response to an ongoing enforcement notice and appeal process.
Planning Strategy
This project required a carefully structured approach, combining multiple planning routes to re-establish a robust and defensible position.
Rather than relying on retrospective justification alone, we implemented a layered planning strategy:
Re-establishing fallback rights through a Prior Approval rear extension (4.5m depth)
Securing a Certificate of Lawful Development for a replacement outbuilding
Introducing a targeted infill element under a full planning application to connect both structures
This sequence allowed us to demonstrate that the majority of the built form could be delivered lawfully, with the planning application addressing only a limited incremental change.
Clarifying Permitted Development Rights
As part of the wider strategy, the project required a detailed review of the site’s permitted development position.
An earlier application for a Certificate of Lawful Development had been refused based on the local authority’s interpretation of the General Permitted Development Order (GPDO). Following a technical review of the proposals, we identified that the assessment did not fully reflect the correct application of the legislation.
We engaged with the planning authority at a senior level to seek clarification on this position. As a result:
The application was reconsidered
The resubmission fee was waived by the Council
A Certificate of Lawful Development was subsequently granted
This outcome was critical in establishing a robust fallback position, which ultimately informed the acceptability of the wider planning strategy.
Navigating Policy Constraints
In isolation, the combined rear extension depth extending to approximately 12.6 metres would typically fall well beyond adopted planning guidance and be unlikely to receive support.
However, the planning authority recognised that:
The extension and outbuilding could be implemented independently under permitted development and lawful consent
The proposal effectively represented a minor linking element between two acceptable forms of development
As confirmed within the officer’s report, the acceptability of the scheme was strongly influenced by the established fallback position, with no unacceptable impact identified in terms of character or amenity
This demonstrates how planning outcomes can differ significantly when fallback positions are properly understood and applied.
Design Approach
The design focused on consolidating the built form into a coherent and functional arrangement:
Introduction of a mono-pitched roof to unify the extension and outbuilding
Rationalisation of the rear massing to improve usability and flow
Retention of a low visual impact, with development largely contained to the rear
Given the limited visibility from the public realm, the proposal was assessed primarily in terms of private impact, which was considered acceptable.
Outcome
Planning permission was granted under delegated powers, with:
No objections received
No adverse impact identified on neighbouring amenity
No concerns relating to parking or character
Crucially, the approval now forms part of a wider enforcement appeal strategy, strengthening the overall planning position of the site.
Why This Matters
This project highlights a key principle:
Planning success is often driven by strategy, not just design.
Where sites are subject to enforcement action or complex planning history, a single application is rarely enough. Instead, successful outcomes are typically achieved through:
Establishing lawful fallback positions
Sequencing applications strategically
Combining permitted development, lawful development and full planning routes
Enforcement & Planning Strategy Specialists
Projects involving enforcement action or disputed planning positions require more than a standard application approach.
At MSK Design, we regularly advise on schemes involving:
enforcement notices and appeals
lawful development certificates
permitted development strategy
planning applications supported by fallback positions
This project is a good example of how a coordinated approach — combining policy, legislation and application sequencing — can help resolve complex planning issues and strengthen an appeal position.
Considering a Similar Project?
If your site is subject to enforcement action, or you’re navigating a complex planning position, a strategic approach can significantly improve your chances of success.
Get in touch to discuss how we can help structure your project for approval.
Call us: 020 3021 2236