Where Does the Money Actually Go? Understanding Development Budgets

If five new homes sell for £750,000 each, the arithmetic looks simple. But when it comes to calculating land value, the development budget behind that figure matters far more than the headline number.

So, £750,000 × 5 gives a scheme worth £3.75 million.

It’s a big number. And it’s easy to assume the land underpinning it all must carry most of that value. But development economics isn’t built on one headline figure. It’s built on a scheme that has been properly costed, funded and adjusted for risk before planning permission is secured and construction begins.

Land value is often one of the first conversations in the development process (after all, nothing moves without the landowner’s agreement). But the true value of land is the residual land value - what remains after a long list of development costs and risks have been carefully accounted for.

In this article, we’ll lift the lid on that calculation and explain how land values are actually determined.

Gross Development Value (GDV): The Headline Number

Gross Development Value (GDV) is the combined sale price of the completed homes. It is the figure most people focus on, and understandably so. It’s the biggest single factor that determines land value.

The problem here, is that it’s the factor that is the very last in a complicated development chain to be realised. Only once every single stage has been completed and the last house has been sold, can one truly confirm the GDV.

And it’s also the factor that everyone can have an opinion on. Every land and homeowner sees house price growth. Every estate agent looks for strong valuations (and valuations that attract clients), and for decades the UK culture has linked positive economic health on strong house prices, often helping to drive house price growth and stability via schemes like first-time buyer, help-to-buy, and shared ownership.

Developers, however, tend to be more risk averse. Overpricing a development by just £25 per square foot on a one-acre, 12,500 sq ft scheme would mean a £312,500 shortfall in the budget. Small differences can suddenly scale if miscalculated.

The difficulty is that, GDV reflects an outcome achieved in the future. 

In most cases, selling a development is 18–36 months away, after planning is achieved, build is complete, and every single unit is officially sold.

House prices have historically trended upward over the long term. But they also fluctuate. Interest rates change. Mortgage affordability tightens or loosens. Employment levels shift. Consumer confidence rises and falls. Pandemics and conflict can affect the economy in ways we cannot predict.

In short, the homes being valued today will be sold into a market that may look very different tomorrow.

GDV is therefore an estimate based on real market data and future-planned risk. It’s certainly not a guarantee.

Construction Costs: The Largest Cost Variable

Construction is the single biggest cost in any property development.

Build costs are often expressed per square foot, but those numbers are not static. Labour availability, material prices, specification choices and regulatory changes all influence the final figure.

A £10 per sq ft shift on our 12,500 sq ft scheme equates to £125,000.

In a volatile construction market, that movement is not unusual. Recently we’ve seen large raw material price changes in wood and steel. The construction industry is seeing more people leave than enter, causing a rise in labour costs too. With fewer workers available, it’s not guaranteed a spade goes in the ground before your two-year planning permission expires.

For developers, the challenge is not simply to calculate build cost, but to calculate it well enough that the scheme remains viable if conditions change.

Professional Fees and Technical Requirements

Unfortunately, planning permission does not come as a single invoice.

The full cost of planning permission includes architects, planners, engineers, ecologists, drainage consultants and highways specialists. Each site brings its own technical requirements. Some are straightforward. Others evolve as discussions with the local authority progress.

Once all reports on the council’s validation checklist are complete you’re not done. Ecological surveys may need updating. Drainage strategies may require redesign. Access arrangements may need refinement.

None of these are exceptional. They are part of the process, but all carry cost and time implications.

Infrastructure Contributions: CIL and Section 106

Community Infrastructure Levy (CIL) and Section 106 contributions exist to support local services, schools, highways and open space once your new development’s community takes occupancy.

These development costs are policy-driven and non-negotiable in many cases. They can represent a significant portion of overall expenditure and viability calculation.

They also vary from authority to authority, meaning no two sites are identical. Councils that have adopted CIL will publish their charging zones and cost per metre, giving you a lot more transparency over this cost. Section 106 contributions, however, are unknown until the specific local services start suggesting appropriate figures.

Finance: The Cost of Time

Development rarely happens overnight.

Capital is committed long before the first home is sold. Planning alone can take 6–12 months. The actual construction and final sales phases add further time.

Development finance costs accrue throughout this period and must be factored into any land development appraisal.

If a scheme takes longer than anticipated — whether due to planning delay, weather, supply chain disruption or market conditions — that time has a cost.

In development, time is rarely neutral.

Risk and Developer Margin

“Margin” is often misunderstood.

It is not simply profit in the conventional sense. It is the allowance that enables a scheme to absorb the many sources of volatility.

Without sufficient margin, even modest movements in sales value or build cost can undermine viability. Lenders require it. Investors expect it. It is what keeps a project resilient.

A scheme that appears generous on paper but carries no risk allowance is unlikely to proceed. And if it does not proceed, no land value is realised.

The Residual: Where Land Value Sits

Once construction costs, professional fees, infrastructure contributions, finance and risk have been accounted for, what remains is the residual land value.

This is why two sites with similar headline GDV can produce very different land valuations.

Overall, development economics is not pessimistic. Rather it is disciplined. It recognises that future sale prices are uncertain, that build costs fluctuate, and that planning and delivery carry risk.

For landowners, understanding this framework is crucial as it allows conversations about value to be grounded in commercial reality rather than raw optimism.

At TruTrade, our approach to land development is simple: we model real build costs, verified sales data and planning risk to determine what your land is genuinely worth.

It is not about minimising land value. It is about ensuring schemes are deliverable.

If you’d like to understand how this framework applies to your own land, we’re always happy to provide a clear, no-obligation appraisal and talk you through it line by line.