Planning policies often place strict limits on the size, design and impact of home extensions. However, there is one powerful planning strategy that many homeowners are unaware of—the fallback position.
A well‑established fallback position can sometimes make the difference between a planning application being approved or refused. If you can demonstrate that a similar (or even more harmful) form of development could be carried out lawfully without planning permission, the local planning authority must consider that as part of its decision‑making process.
What Is a Fallback Position?
A fallback position is a form of development that could lawfully be carried out if planning permission for your preferred proposal were refused.
Common examples include:
- Development permitted under Permitted Development Rights.
- Development confirmed through a Certificate of Lawful Development (LDC).
- Development approved through the Prior Approval process, such as larger home extensions.
A fallback position can demonstrate that refusing planning permission may not prevent development—it may simply result in a less attractive or less neighbourly alternative being built instead.
Why Are Fallback Positions Important?
Planning officers are required to assess the realistic planning consequences of refusing permission. If there is a genuine prospect that a lawful fallback would be implemented, it can become a material planning consideration.
For example:
- A planning application proposes a 4‑metre rear extension with high‑quality design.
- The homeowner already has a lawful fallback allowing a 3‑metre extension under Permitted Development.
- The proposed extension creates no greater planning harm than the fallback.
In some cases, granting permission may produce the better overall planning outcome.
The Legal Position
The courts have confirmed that fallback positions can be relevant planning considerations where they have a genuine prospect of being implemented. One leading case is Mansell v Tonbridge and Malling Borough Council 2017, which established that a fallback should generally:
- Have a realistic prospect of implementation.
- Be lawful.
- Be materially comparable with the proposed development.
Simply suggesting a theoretical fallback is unlikely to carry significant weight.
Certificates of Lawful Development
One of the strongest ways to establish a fallback position is by obtaining a Certificate of Lawful Development (LDC). A proposed LDC confirms that development would be lawful under the General Permitted Development Order (GPDO).
Common examples include:
- Rear extensions.
- Loft conversions.
- Garage conversions.
- Outbuildings.
Unlike planning permission, an LDC does not grant approval—it confirms that planning permission is not required.
Our guide Permitted Development Rights Explained: What Can You Build Without Planning Permission? explains how Permitted Development Rights operate.
Using an LDC as a Fallback
- Obtain a Certificate of Lawful Development.
- Submit a planning application for an improved design.
- Demonstrate that the proposal creates no greater planning harm than the lawful fallback.
Example: A homeowner obtains an LDC for a 3‑metre rear extension under Permitted Development before applying for planning permission for a carefully designed 4‑metre extension. The planning authority must then consider the lawful fallback when assessing the application.
Prior Approval as a Fallback
Some forms of development are permitted through Prior Approval rather than full planning permission. A common example is the Larger Home Extension Scheme, which allows:
- Up to 6 metres for terraced and semi‑detached houses.
- Up to 8 metres for detached houses.
Subject to the relevant conditions, obtaining Prior Approval can create a strong fallback position for a subsequent planning application.
Our guide Planning Permission vs Building Regulations: Do You Need One, the Other, or Both? explains how Prior Approval differs from planning permission.
Common Householder Examples
Rear Extensions
A homeowner secures Prior Approval for an 8‑metre rear extension. They later submit a planning application for a 6‑metre extension with improved architecture, rooflights and higher‑quality materials. Although planning permission is required, the fallback demonstrates that a larger extension could already be built.
Loft Conversions
A large rear box dormer may qualify under Permitted Development. Instead, the homeowner seeks planning permission for a smaller pitched‑roof dormer that better complements the property. The lawful PD dormer becomes the fallback position.
Wraparound Extensions
Separate side and rear extensions may each qualify under Permitted Development. However, combining them into a single wraparound extension often requires planning permission. The fallback may demonstrate that the combined design actually produces a more coherent and less visually intrusive result.
Garage Conversions
Many garage conversions are permitted development. Obtaining an LDC before applying for planning permission for a more ambitious conversion can strengthen the planning case.
Presenting a Fallback Position
A convincing fallback argument should include:
- The Certificate of Lawful Development or Prior Approval decision.
- Comparative drawings.
- A clear explanation of the planning differences.
- Evidence that the fallback could genuinely be implemented.
The more realistic the fallback appears, the greater weight it may receive.
When Are Fallback Arguments Most Effective?
Fallback positions are particularly valuable where:
- Local planning policies are restrictive.
- The proposal exceeds normal planning guidance.
- Design improvements are being offered.
- Negotiations with planning officers are ongoing.
- Refusal could result in a less desirable lawful development.
They are often especially useful for extensions within established residential areas.
Limitations
The Fallback Must Be Realistic
Planning authorities will generally give little weight to hypothetical development that has little prospect of ever being constructed.
Permitted Development Rights May Be Removed
Article 4 Directions or planning conditions may remove Permitted Development Rights. In these circumstances, no fallback may exist.
Good Design Still Matters
Even where a fallback exists, planning authorities will still assess design quality, character, neighbouring amenity and planning policy. A fallback does not automatically justify poor design.
Why Professional Advice Matters
Developing a successful fallback strategy requires careful analysis of both planning legislation and local policy. Obtaining a Certificate of Lawful Development before submitting a planning application can sometimes provide significant negotiating advantages, but each project requires its own assessment. Professional advice can help determine whether establishing a fallback position is worthwhile before investing in detailed design work.
How Draw & Plan Can Help
At Draw & Plan, we regularly advise homeowners on whether a lawful fallback position can strengthen a planning application. Our Planning Drawings service includes advice on Permitted Development Rights, Certificates of Lawful Development, Prior Approval applications and full planning applications, helping clients identify the most effective planning strategy before work begins.
Where projects proceed to construction, our Building Regulations Drawings provide the detailed technical information required for Building Control approval.
If you’re unsure whether your project qualifies under Permitted Development, the Government’s Permitted Development Rights for Householders Technical Guidance and the Planning Portal’s guide to Permitted Development provide useful background information.
Ready to discuss your project? Contact us today for a free, no‑obligation quotation.
Further Reading