Planning Viability Assessment

A planning viability assessment is a technical financial evaluation used within the UK planning system to determine whether a proposed development is economically deliverable. It calculates whether the value generated by a site, after accounting for all construction costs, professional fees, and developer profit, is sufficient to pay for policy-mandated contributions such as affordable housing and infrastructure levies.

Key Takeaways

• Financial Foundation: Viability assessments compare the “Residual Land Value” against the “Benchmark Land Value” to establish project feasibility.
• Policy Compliance: They are the primary tool used to negotiate reductions in Section 106 obligations or affordable housing requirements when costs are prohibitive.
• Standardised Methodology: The process follows the RICS Professional Statement and the National Planning Policy Framework (NPPF) guidelines.
• Transparency Requirements: Most local authorities now require these reports to be made public, with very few exceptions for commercial sensitivity.
• Strategic Timing: Engaging a consultant early in the site feasibility stage prevents the acquisition of land at prices that render development impossible.
• Professional Expertise: These assessments require input from RICS-qualified surveyors and experienced planning consultants to withstand rigorous council scrutiny.

What is a Planning Viability Assessment?

In the context of UK property development, a planning viability assessment serves as a bridge between the aspirational goals of local planning authorities and the economic realities of the construction industry. At its core, it is an objective test of whether the requirements of a planning permission—such as the provision of affordable housing—would make a project financially impossible to complete.
The assessment focuses on the relationship between “Gross Development Value” (GDV) and the total cost of bringing the project to fruition. If the costs of development, including a reasonable profit margin for the developer, exceed the expected revenue, the project is deemed unviable under the current set of planning obligations.

Local authorities use these documents to ensure that the “material considerations” of a site are balanced against the need for community benefits. While the primary goal of the planning system is to secure sustainable development, the government acknowledges that onerous requirements should not stall the delivery of much-needed housing and commercial space.

The Core Formula of Viability

While the internal dynamics of a report are complex, the logic follows a specific hierarchical structure. To understand how a planning viability assessment functions, one must understand the “Residual Valuation” method:

Gross Development Value (GDV) 
- Total Development Costs (Construction, Fees, Finance) 
- Developer’s Profit 
= Residual Land Value (RLV)

For a project to be considered viable, the Residual Land Value (RLV) must be equal to or greater than the Benchmark Land Value (BLV). If the RLV falls below the BLV, the developer is effectively losing money by proceeding, providing the justification for a negotiation of planning terms.

Component	Description	Standard Benchmark
Gross Development Value	The total market value of the finished development.	Based on comparable local sales data.
Construction Costs	Hard costs of building, including materials and labour.	BCIS rates or tender-based estimates.
Professional Fees	Architects, surveyors, planning consultants, and engineers.	Typically 8% to 12% of build costs.
Developer Profit	The return required to justify the risk of the project.	Usually 15% to 20% on GDV or Cost.
Benchmark Land Value	The value of the land in its current use plus a premium.	Existing Use Value (EUV) + Premium.

When is a Planning Viability Assessment Required?

Not every application requires a detailed financial breakdown. However, for larger residential schemes or complex mixed-use developments, a planning viability assessment becomes an essential component of the planning statement. We typically recommend these assessments in the following scenarios:

1. Negotiating Affordable Housing Percentages

Most Local Plans set a target for affordable housing, often ranging from 20% to 50% of the total units. If site-specific constraints—such as high remediation costs or heritage requirements—make this target unreachable, an assessment provides the evidence needed to lower that percentage.

2. Challenges to Section 106 and CIL Contributions

Financial contributions towards local infrastructure, education, and transport (Section 106) or the Community Infrastructure Levy (CIL) can be substantial. If these costs, combined with other “material considerations,” threaten the project’s delivery, a viability report is the only formal mechanism to request a reduction.

3. Change of Use and Redundant Buildings

Converting a listed building or a former industrial site often involves unforeseen structural and environmental costs. When applying for a change of use, demonstrating that the current use is no longer viable and that the proposed use requires financial flexibility is key to securing approval.

4. Review Mechanisms on Multi-Phase Sites

On larger developments that take years to complete, councils may impose “late-stage viability reviews.” These allow the authority to capture more funding if the market improves during the construction period. A robust initial planning viability assessment sets the baseline for these future reviews.

The Methodology of Benchmark Land Value

The National Planning Practice Guidance (PPG) is explicit about how land should be valued for viability purposes. The “Existing Use Value Plus” (EUV+) approach is the mandatory standard. This prevents developers from overpaying for land based on “hope value” and then using that high purchase price to argue that they cannot afford to provide affordable housing.

Existing Use Value (EUV)

This is the value of the land in its current state, assuming it continues to be used for its existing purpose (e.g., as a warehouse or a low-grade office). It ignores any potential uplift that the new planning permission might bring.

The Landowner Premium

To incentivise a landowner to sell, a premium is added to the EUV. This premium must be high enough to encourage the sale but not so high that it absorbs the funds intended for community infrastructure. A typical premium might range from 10% to 30%, though this varies based on the specific circumstances of the site.

We work closely with clients during the site feasibility stage to ensure the price paid for land aligns with these regulatory realities. Overpaying for a site is not accepted as a valid reason for failing to meet planning obligations.

Key Components of the Assessment Report

A professional planning viability assessment produced by our firm is a comprehensive document that leaves no room for ambiguity. It must stand up to the scrutiny of the District Valuer Services (DVS) or independent consultants hired by the council.

1. Revenue Analysis (GDV)

We provide a detailed breakdown of the expected sales values for each unit type. This is backed by recent “sold” prices of comparable properties in the immediate vicinity. For commercial elements, we analyse yield rates and market rents to ensure the valuation is grounded in current economic data.

2. Detailed Cost Estimates

Construction costs are never “guessed.” We use data from the Building Cost Information Service (BCIS) of the RICS, adjusted for the specific location and the quality of the architectural design. We also include “abnormal costs,” such as:

• Contamination remediation and soil stabilisation.
• Demolition of existing structures.
• Archaeological investigations.
• Upgrading utility connections and substations.
• Specialist materials required for heritage compliance.

3. Finance and Holding Costs

Development involves significant debt. We account for interest rates, arrangement fees, and the “cost of money” over the entire duration of the project—from the initial site feasibility study through to the final sale of the last unit.

4. Professional Fees and Marketing

A successful development requires a team of experts. We include allowances for architects, planning consultants, structural engineers, and legal fees. Furthermore, the costs of marketing, estate agency commissions, and show-home fit-outs are factored into the final calculation.

The Role of Developer Profit

A common misconception is that developer profit is an optional extra. In a planning viability assessment, a reasonable profit is considered a fixed cost of development. Without a guaranteed return, lenders will not provide the necessary finance, and the project will not proceed.

The standard range for developer profit in the UK is generally 15% to 20% of the Gross Development Value. For lower-risk elements, such as the delivery of affordable housing units to a registered provider, the profit margin may be lower (typically around 6%). We negotiate these margins based on the specific risk profile of your project.

The Importance of Transparency and Public Scrutiny

Since 2019, the government has mandated that planning viability assessments should be prepared on an “open book” basis. This means the report will be published on the local authority’s planning portal for the public to view.

While some financial data can be redacted if it is proven to be commercially sensitive, the “Executive Summary” must remain public. This shift has placed a premium on accuracy. If your figures are seen as unrealistic or artificially inflated, it can lead to significant reputational damage and a swift refusal of the application.

Handling Redactions

We ensure that sensitive information—such as specific land purchase contracts or proprietary business models—is handled with care. However, we advise all clients that the “burden of proof” for confidentiality is high. Our reports are written with this transparency in mind, ensuring they are persuasive to the council while protecting your core interests.

Common Challenges in Viability Negotiations

The path to a successful planning viability assessment is rarely without obstacles. Local authorities are under immense pressure to meet affordable housing targets and may naturally be sceptical of a developer’s claim that a project is unviable.

• The “Price Paid” Trap: Councils will ignore the price you actually paid for the land if it exceeds the Benchmark Land Value. They view this as a commercial risk taken by the developer, not a planning concern.
• Conflict Over BCIS Rates: Disagreements often arise regarding which construction cost index to use. We provide robust justifications when your project requires costs above the standard median rates.
• Optimistic Sales Valuations: Planning officers may argue that your GDV is too low, suggesting that market growth will make the site viable by the time it is built.
• Abnormal Cost Disputes: What a developer considers an “abnormal” cost, a council might consider a “standard” risk of development. We use technical reports to prove the necessity of every expense.

The Strategic Advantage of Early Assessment

Waiting until after a planning refusal to consider viability is a tactical error. The most successful developers integrate the planning viability assessment into their initial site feasibility and design process. This proactive approach offers several benefits:

1. Design Optimization: If the initial viability looks thin, we can work with your architects to adjust the unit mix or density to improve the GDV before the application is submitted.
2. Negotiation Leverage: Entering discussions with a fully costed report puts you in a position of strength. It demonstrates that you are a professional operator who understands the constraints of the site.
3. Risk Mitigation: Knowing the “break-even” point of a development allows you to walk away from projects that are mathematically destined to fail, saving years of wasted effort and significant capital.
4. Speed to Approval: By addressing viability upfront, you avoid the lengthy delays that occur when a council requests this information mid-way through the determination period.

We act as the essential bridge between your architectural vision and the rigid financial requirements of the planning system. Our goal is to ensure that your project is not only approved but is also capable of being built profitably.

The Relationship with Section 106 Agreements

A Section 106 agreement is a legally binding deed that accompanies a planning permission. It outlines the specific contributions a developer must make. A planning viability assessment is the primary tool used to shape the terms of this deed.

If we successfully demonstrate that a site cannot support the full suite of contributions, the Section 106 agreement will be drafted to reflect the reduced requirements. This might include a “cascade” mechanism, where the level of affordable housing is tied to the actual performance of the development once construction begins.

Our expertise ensures that the wording of these agreements is precise. We protect you from “unreasonable” requests from the local authority that go beyond what is necessary to make the development acceptable in planning terms.

Frequently Asked Questions

Does a viability assessment guarantee a reduction in affordable housing?

No, it does not guarantee a reduction, but it provides the legal and financial evidence required for the council to consider one. The decision rests on the council’s assessment of your evidence. However, a professionally prepared planning viability assessment significantly increases the likelihood of a favourable outcome by proving that the project would otherwise not proceed.

What is the difference between viability and feasibility?

While often used interchangeably, “feasibility” usually refers to the physical and practical ability to build on a site (e.g., access, topography, and planning policy). “Viability” specifically refers to the financial deliverability of the project, focusing on the profit-and-loss margins after all costs and obligations are met.

How long does it take to prepare a viability report?

A comprehensive assessment typically takes 3 to 6 weeks to prepare. This timeline depends on the availability of cost data from surveyors and the complexity of the proposed scheme. We recommend starting this process as early as possible in the site feasibility stage.

Can I submit a viability assessment for a small residential extension?

It is rarely necessary for small-scale residential extensions, as these projects usually do not trigger affordable housing or significant infrastructure contributions. These assessments are primarily used for “major developments”—typically those involving 10 or more dwellings or large commercial floor spaces.

Will the council hire their own surveyor to check the report?

Yes, most local authorities will appoint an independent surveyor (often from the DVS or a private firm) to review your planning viability assessment. The cost of this independent review is usually paid for by the applicant. We manage the dialogue with these reviewers to defend your position and reach an agreement on the figures.

What happens if the market changes during the planning process?

If there is a significant shift in the market (e.g., a sharp rise in construction costs or a drop in house prices), the assessment can be updated. We often use “sensitivity analysis” within our reports to show how the project’s viability would change under different economic scenarios.

Is it possible to appeal a decision based on viability?

Yes. If a council refuses a planning application because you cannot meet their full contribution requirements, and your planning viability assessment proves those requirements are unreasonable, you can appeal to the Planning Inspectorate. The Inspector will then conduct a detailed review of the financial evidence provided.

The complexities of the UK planning system demand a high level of technical precision. At Approved Planning, we pride ourselves on being more than just consultants; we are strategic partners in your development journey. By combining deep industry knowledge with a rigorous approach to financial modelling, we ensure that your development goals are met with the necessary legal and procedural security.