Planning a building project in London can feel overwhelming. Between local planning rules, heritage considerations, and construction budgets, many homeowners and developers struggle to know if a site or idea is practical before investing heavily. An architectural feasibility study solves this problem by providing a clear picture of what is possible, what permissions are required, and how much the project is likely to cost. In this guide, we explain every stage of a feasibility assessment and planning appraisal, share practical examples from London projects, and highlight how these studies help avoid costly surprises. Even if you are considering a house extension, a new build, or a change of use, understanding the value of a well-prepared feasibility study will save time, money, and stress.
An architectural feasibility study is an early-stage investigation that evaluates the potential of a site or property before detailed design work begins. It examines planning policies, structural limitations, budget factors, and any technical constraints that could affect development. By reviewing these elements in advance, architects provide clients with a realistic outline of what can be built and what challenges might arise. A comprehensive study typically includes a planning policy review, site analysis, initial sketches or massing diagrams, and a cost assessment. For projects in London, this process is invaluable because boroughs have specific design guides and strict planning frameworks. A well-prepared report gives clear guidance, enabling property owners to make informed decisions about purchasing land, applying for permission, or adjusting their ambitions to match site conditions.
London presents unique planning challenges due to its dense urban layout and varied architectural heritage. Many sites are located in conservation areas, near listed buildings, or within zones affected by the London Plan and local borough policies. These factors can limit building height, materials, or even the type of development permitted. A feasibility study identifies these issues before significant funds are committed. For example, projects near the Green Belt or in areas of archaeological interest often require specific surveys and additional approvals. Early awareness of such requirements prevents delays and redesigns. Developers and homeowners who commission feasibility studies gain a competitive advantage because they understand constraints and opportunities from the outset, allowing them to budget accurately and avoid unexpected planning refusals.
A robust feasibility assessment for any development project involves several essential elements, each providing critical insights for decision-making. The process typically begins with a site and context analysis, which evaluates key factors such as site access, orientation, topography, and relationships to neighbouring properties. This step helps identify both opportunities and potential constraints related to the land itself.
Next is a planning policy review, where experts examine relevant national policies, the London Plan, and specific guidance from the local borough. This ensures that any proposals align with the latest planning rules and avoids unexpected policy conflicts.
Initial design concepts are then explored to visualise possible layouts, building massing, and architectural forms. These early sketches help clarify what can realistically be achieved on the site.
An important practical component is the budget and cost estimate. This provides an outline of likely construction costs as well as professional fees, helping clients judge whether a scheme is financially viable from the outset.
A risk assessment is also carried out to identify potential legal, environmental, or technical challenges at an early stage. This proactive approach allows teams to plan for and mitigate risks before significant costs are incurred.
Additionally, a sustainability review considers the project’s energy performance and environmental impact, ensuring proposals can meet modern expectations for responsible development.
Each of these elements contributes to an evidence-based, balanced feasibility report. Including a thorough planning appraisal further enhances the study, as it examines how local policies and past planning decisions could influence the likelihood of gaining approval for the proposed scheme. This comprehensive approach gives clients the clarity they need to proceed confidently.
The best time to carry out a feasibility study is before purchasing a site or starting detailed design work. Commissioning a study early allows you to check whether your vision aligns with planning rules and site conditions. Homeowners often use feasibility studies when considering significant house extensions or basement conversions, while developers rely on them to evaluate the potential of a land acquisition. If you are planning a project in an area with strict heritage controls or complex access issues, an early feasibility review is essential. It also provides a strong basis for discussions with lenders or investors, as they can see a realistic assessment of risks and projected costs.
At dRAW Architecture, we approach feasibility studies with a combination of site visits, research, and concept design. Our architects start by meeting the client to discuss goals, budget, and timelines. We then carry out a detailed site inspection to understand constraints such as neighbouring properties, access, and existing structures. Next, we analyse relevant planning policies from the London Plan and the local borough, identifying opportunities and potential obstacles. Using this information, we create initial concept sketches and, where helpful, simple 3D models to illustrate possible layouts. Finally, we compile our findings into a clear report that outlines recommended next steps, potential costs, and a realistic project programme. This method ensures clients have a full understanding of the project’s viability before proceeding to RIBA Stage 2 design.
Although often mentioned together, planning appraisals and feasibility studies are not identical. A planning appraisal focuses on how planning policies affect a particular site or proposal. It reviews local development plans, recent planning decisions, and national guidance to gauge the likelihood of receiving planning permission. A feasibility study is broader, covering technical, financial, and design considerations in addition to planning. Many projects benefit from combining the two, as the planning appraisal provides specific policy insight while the feasibility study offers a full picture of buildability, costs, and potential design solutions. This combined approach gives clients the best chance of success when moving on to pre-application advice or a full planning submission.
The cost of a feasibility study varies depending on project scale, site complexity, and the level of detail required. For a small house extension, a straightforward study might start at £1,500–£3,000, while larger residential or mixed-use developments can require fees from £5,000 upwards. Factors influencing price include the need for specialist surveys such as ecology or flood risk assessments, the amount of design work required, and the level of engagement with planning authorities. Although this represents an upfront investment, it often saves significant money by highlighting potential issues before detailed design or construction begins. Transparent pricing and a clear scope of work are essential, so clients know exactly what the report will deliver.
For a Victorian terrace in Kensington, our study revealed that a modest rear extension would meet local conservation guidelines, while a proposed roof terrace required additional heritage consultation. The client adjusted the design early, saving months of potential delays.
A developer considering a warehouse-to-office conversion in Shoreditch needed clarity on permitted use changes. Our planning appraisal confirmed the viability of a mixed-use scheme and identified key transport and access requirements.
In a suburban Green Belt location, our team analysed local policy to determine if a new residential dwelling was possible. The study found limited development rights but identified opportunities for a sustainable replacement building.
Each example demonstrates how a clear feasibility assessment prevents unexpected refusals and gives clients a roadmap to successful planning applications.
Once a feasibility study confirms a project is viable, the next step is usually pre-application advice with the local planning authority. This stage allows informal feedback on design concepts and can highlight any remaining concerns before a full planning submission. Following a positive pre-app response, architects move to detailed design, preparing drawings and documents for a formal planning application. A strong feasibility report provides all the background information needed for these stages, including site constraints, design options, and cost expectations. By moving forward with this solid foundation, clients reduce the likelihood of expensive redesigns and improve their chances of a smooth approval process.
Selecting an architect with proven London experience is vital. Look for professionals who are ARB registered and RIBA chartered, as these qualifications ensure adherence to professional standards and up-to-date knowledge of UK building regulations. Review their portfolio to confirm they have successfully completed feasibility studies and planning applications similar to your project. At Draw Architecture, we provide a written proposal outlining scope, costs, and timeline so clients understand exactly what to expect. Choosing a team that communicates clearly and demonstrates local planning expertise will give you the confidence to proceed with your project, knowing that potential issues have been thoroughly assessed.
An architectural feasibility study is the smartest investment you can make before committing to a build in London. By identifying planning restrictions, estimating realistic costs, and outlining design possibilities, it removes guesswork and protects your budget from expensive surprises. At Draw Architecture, our team of ARB-registered, RIBA-chartered architects uses local planning knowledge and detailed site analysis to give you a clear path forward. Whether you are planning a house extension, a new build, or a conversion, commissioning a feasibility assessment today means you begin with facts, not assumptions. Contact us to arrange your Architectural Feasibility Study in London and move your project toward a successful planning application with complete peace of mind.
