For small property developers in the UK, viability is the foundation of every successful project. You can secure a strong site, receive positive pre-application feedback and design a scheme that works on paper, however if the numbers do not stack up, the development will ultimately fail.
At Planning House, we see viability issues derail schemes far more frequently than planning refusals. With rising construction costs, increasing policy requirements and tighter margins, understanding development viability has never been more important. So how can you assess whether your scheme will actually make money, before committing to a site?
What Does “Viability” Really Mean in Property Development?
In simple terms, development viability is the relationship between cost and value. A scheme is considered viable if the Gross Development Value (GDV) exceeds the total cost of delivering the project, leaving a sufficient profit margin. However, in practice, viability is far more complex.
A robust appraisal needs to account for:
- Land acquisition costs;
- Build costs (which vary by location, specification and contractor);
- Professional fees, including planning consultants, architects, engineers and associated surveys or assessments;
- Planning obligations such as Community Infrastructure Levy (CIL) and Section 106 developer contributions;
- Finance costs, including interest and arrangement fees; and
- Sales values based on local market conditions.
It is not uncommon for schemes that appear profitable at a high level to become marginal once these factors are fully considered.
The Key Viability Challenges Facing Small Developers
In the current market, we are seeing three consistent pressures impacting small development schemes across the UK.
Build cost inflation remains a significant challenge. Even relatively small increases in labour or materials can have a disproportionate effect on schemes delivering between one and five units.
At the same time, planning policy requirements are becoming more demanding. Biodiversity Net Gain, parking standards, and higher design expectations can all increase costs or reduce the number of units achievable on a site.
Finally, sales value uncertainty is creating additional risk. In some areas, property values are not keeping pace with construction costs, placing further pressure on margins and reducing developer confidence.
Why Early Viability Appraisal Is Critical
One of the most common mistakes small developers make is assessing viability too late in the process. A proper viability appraisal should be undertaken at the earliest possible stage (we recommend you seek professional help on this if you’re unsure), ideally before:
- Purchasing the land;
- Submitting a planning application; and
- Commissioning detailed design work
By this point, financial commitments have often already been made, limiting flexibility and increasing risk. The most successful developers take a plan-led approach, testing multiple development scenarios and stress-testing assumptions around cost and value before progressing.
Viability as a Strategic Tool
Viability is not just a financial calculation, it is a strategic tool that informs every stage of development. It influences, what type of scheme to pursue, how many units to propose and whether a site is worth acquiring at all.
Treating viability as an ongoing process, rather than a one-off exercise, allows developers to respond to changing costs, policy requirements and market conditions.
Final Thoughts
In today’s market, small-scale development is becoming more complex, but also more dependent on getting the fundamentals right.
Viability sits at the centre of that process. If you understand your numbers early, you can make informed decisions, reduce risk and improve your chances of delivering a successful scheme.
Related Content
There are costs in planning, our The Hidden Costs of Planning blog can assist in identifying some of these. In planning developer contributions are a much overlooked part of the process, take a look at our blog Navigating Developer Contributions – A Guide to Section 106 Agreements. More information about Planning Obligations / s106 Agreements can be view in the National Planning Practice Guidance.
Take a look at our eBook: CIL & s106 – which gives the basics on CIL (Community Infrastructure Levy) and developments which may trigger the need for additional works or financial contribution (via s106 agreement). It’s better to know in advance what the financial implications might be.
If you are in a situation where you need to look at modification of a s106 Planning Agreement take a look at our Practical Guide: Modification of s106.
