, Property
The agent says the site is on at £420,000 and there is interest. You have a scheme in mind for six houses. The question is not whether £420,000 feels like a lot of money. It is whether six houses, built and sold, leave you with £420,000 plus a profit after everything else has been paid. If they do not, no amount of enthusiasm about the location changes the answer.
That calculation is a residual appraisal, and it is the only honest way to price land.
The residual runs backwards, and everything in the middle is a cost
The structure is simple enough to write on one line. Take what the finished development will sell for. Subtract what it costs to build, what the professionals cost, what the finance costs, and the profit you require. What is left is what you can pay for the land.
Gross development value is the total sale price of everything you will sell: the houses, the flats, any commercial unit, and any ground rent or retained interest. It is a valuation, not a hope. You build it from comparable evidence, which means actual sold prices for genuinely similar new homes in the same location, adjusted for size and specification, not asking prices on the portals. Land Registry price paid data is public and it is the thing to use, because asking prices in a new build scheme include incentives that never show on the listing.
Then the deductions, in the order they hurt:
- Build cost, priced per square metre of gross internal area for the relevant building type and region. The RICS Building Cost Information Service publishes indexed cost data used across the industry, and a quantity surveyor's estimate is worth paying for on anything above a couple of units.
- Externals and abnormals. Roads, drainage, service connections, retaining walls, demolition, remediation of contaminated ground, piling where the ground is poor, and tree protection. These do not appear in a per square metre rate and they sink small schemes.
- Professional fees, commonly around 10% to 15% of build cost, covering architect, structural engineer, planning consultant, quantity surveyor, building control, ecology and whatever surveys the planning conditions demand.
- Planning obligations: a section 106 agreement and the Community Infrastructure Levy, where the authority charges it. Both are calculable in advance from published charging schedules.
- Finance, which is discussed below and is routinely understated.
- Sales and marketing, including agents' fees and legal costs on each plot.
- Contingency, typically 5% to 10% on build cost, and more on a conversion where you cannot see what you are buying.
- Developer's profit.
Subtract all of that from the gross development value and the number remaining is the residual land value, before you take off the stamp duty and legal costs of buying the land itself.
Profit is a cost, not a leftover
The most common mistake in a first appraisal is treating profit as whatever emerges. It is an input. You decide it, and the land price adjusts.
The usual measures are profit on cost, meaning profit divided by total development cost, and profit on gross development value. Lenders on residential development schemes have conventionally wanted to see something in the region of 17.5% to 20% on cost, and will size their facility on the assumption that it is there. That is not greed. It is the buffer between a scheme that survives a 5% fall in values and one that wipes out your equity.
The reason the convention exists is that development is leveraged twice. You are geared financially, and you are geared operationally, because your costs are largely fixed once you start and your revenue is not. A 5% fall in sale prices on a scheme with a 20% margin removes a quarter of the profit. A 10% fall, combined with a 10% build cost overrun, removes all of it. That is not a tail event, that is an ordinary two years in the British housing market.
Finance costs more than the headline rate
Development finance is not priced like a mortgage. On a typical facility you will meet an arrangement fee of 1% to 2% of the loan, an exit fee sometimes charged on loan and sometimes on gross development value, monitoring surveyor fees payable monthly for the lender's inspections, and interest charged on the drawn balance.
Interest is usually rolled up, meaning it is added to the loan rather than paid monthly. That is a cash flow convenience and a psychological trap: the cost accumulates silently and lands at redemption. Model it properly on a drawdown schedule, because interest on money drawn in month two runs for the whole project and interest on money drawn in month ten does not.
The variable that matters most is time. Development finance is priced monthly, so a three-month overrun on a twelve-month scheme is a 25% increase in the interest bill, plus an extension fee if the facility term is exceeded. Overruns come from weather, from a condition that could not be discharged, from a groundworker going into administration, and from the sales period running longer than planned because the last two plots are the hardest to shift. The appraisal should contain a sales period, not an assumption that everything sells on practical completion.
Sensitivity analysis is where the appraisal earns its keep
One number is not an appraisal. It is a guess with decimal places. What you want to know is how wrong the inputs can be before the scheme fails.
Run it three ways. Move the gross development value down by 5% and 10%. Move build cost up by 10%. Extend the programme by three and six months. Then look at the profit under each, and at the combination of two adverse moves at once, because reality tends to deliver correlated bad news: a slowing market lengthens the sales period at the same time as it reduces the price.
The output is a walk-away land price rather than a bid. Knowing the maximum you can pay, and why, is the whole discipline. Developers who bid on sentiment win sites and lose money, and developers who bid on the residual lose more sites than they win. Losing sites is the correct outcome most of the time.
It is also worth understanding that this same arithmetic runs in the other direction in the planning system. Where a scheme cannot support the policy-compliant level of affordable housing, applicants submit a viability assessment built on a residual appraisal, and the local authority scrutinises the inputs. Existing use value plus a premium is the usual benchmark for the land. Knowing how the calculation works is therefore useful for negotiating consent as well as for pricing a purchase.
Where this shows up in the game
Housebuilding and development arrive in Business Baron with the Property & Construction Track, an add-on to the full game. A scheme is a project with months of cost in it before anything sells, and the cash flow shows every one of them. A site bought above what the finished homes can support can still be built, and the profit will simply not be there at the end.