Quick Answer
A development appraisal is a financial test of whether a building project is worth doing. It works out the gross development value (GDV), meaning what the finished scheme will be worth, then deducts every cost: build costs, professional fees, finance, planning obligations, sales costs and the developer’s profit. What’s left is the residual land value, the most a developer can sensibly pay for the site. This is known as the residual method of valuation. Developers use appraisals to decide what to offer for land, lenders use them to assess loans, and councils use viability appraisals to decide how much affordable housing and other contributions a scheme can support. Government guidance suggests a developer’s return of 15% to 20% of GDV is often a suitable assumption.
Why Every Development Starts With the Numbers
A plot of land with planning potential can look like a goldmine. Whether it actually is depends on the numbers.
Pay too much for a site and your profit can vanish before the first brick is laid. Underestimate build costs or overestimate sale prices, and a promising scheme can quickly lose money. A development appraisal stops that happening. It tells you, before you commit, whether the sums add up and how much the land is really worth to you.
Think of it like planning a big home renovation in reverse. Instead of adding up costs and hoping the house is worth more afterwards, you start with what it’ll be worth when it’s finished, take off everything it costs to get there, and see what’s left.
Our Chartered Surveyors and RICS Registered Valuers prepare development appraisals for residential and commercial schemes across Stoke-on-Trent, Staffordshire, Cheshire and Shropshire. This guide explains how they work, in plain English.
Already know you need one? Go straight to our development appraisal service.
How a Development Appraisal Works
Most appraisals use the residual method. The formula is simple:
Gross development value − total development costs − developer’s profit = residual land value
The skill lies in getting each figure right.
Step 1: Work out the gross development value (GDV)
The GDV is what the completed scheme will be worth. Depending on the project, that might be:
- The sale price of each new home or commercial unit
- The capital value of the finished building, based on the rent it can earn
- Other income, such as ground rents or car parking
GDV is based on evidence, not hope. Surveyors use recent comparable sales and lettings, HM Land Registry data, local agents’ knowledge and current market conditions. Because every other figure follows from it, an optimistic GDV is the most common reason appraisals go wrong.
Step 2: Add up the development costs
Next comes everything it will cost to deliver the scheme:
| Cost | What it includes |
| Build costs | Construction, site preparation, demolition, infrastructure and external works |
| Professional fees | Architects, engineers, surveyors and project managers, often 8% to 12% of build costs |
| Contingency | A buffer for the unexpected, usually around 5% of build costs |
| Planning and statutory costs | Planning fees, Section 106 contributions, Community Infrastructure Levy, affordable housing, biodiversity net gain, building control and party wall agreements |
| Finance | Interest and fees on development loans over the life of the project |
| Sales and letting costs | Agents’ fees, marketing and legal fees on sales or lettings |
| Holding costs | Business rates, insurance and security on empty buildings before they’re sold or let |
| Land acquisition costs | Stamp duty, legal and survey fees on buying the site |
Step 3: Allow for the developer’s profit
No developer takes on the risk of a project for nothing. The appraisal builds in a profit, usually as a percentage of GDV. Government planning guidance says a return of 15% to 20% of GDV may be a suitable assumption, with a lower figure for lower-risk elements such as affordable housing.
Step 4: Find the residual land value
Take the costs and profit away from the GDV, and what’s left is the residual land value. That’s the most you can pay for the site and still make your target return.
If the asking price is higher than the residual value, the scheme doesn’t work at that price. You can negotiate, change the design, or walk away.
Other ways to run an appraisal
The residual method can also be turned around. If you already own the land, or know the price, you can put the land cost in and solve for profit instead. That tells you what return the scheme will actually make, which is what lenders want to see. Larger schemes often use a cash flow appraisal, which tracks costs and income month by month to model the true cost of finance.
A Worked Example
Picture a developer looking at a small site on the edge of Stoke-on-Trent with outline planning permission for eight family homes. The landowner wants £400,000. Is that a fair price?
Here’s a simplified residual appraisal. The figures are illustrative only.
| Item | Amount |
| Gross development value (8 homes at £250,000) | £2,000,000 |
| Build costs | £1,000,000 |
| Professional fees (10% of build) | £100,000 |
| Contingency (5% of build) | £50,000 |
| Section 106, CIL and biodiversity net gain | £40,000 |
| Finance costs | £90,000 |
| Sales and legal fees (2.5% of GDV) | £50,000 |
| Total development costs | £1,330,000 |
| Developer’s profit (17.5% of GDV) | £350,000 |
| Residual land value | £320,000 |
After allowing for stamp duty and fees on buying the site, the most the developer should offer is around £310,000, not £400,000. At the asking price, the scheme would either make a much smaller profit or need to be redesigned.
Why small changes matter so much
Now imagine house prices come in 5% lower than expected, at £237,500 each. The GDV falls to £1,900,000, and the profit allowance to £332,500. Costs stay the same.
The residual land value drops to £237,500. A 5% fall in sale prices has cut what the land is worth by around a quarter.
That’s the nature of a residual appraisal. Because the land value is what’s left at the end, it swings far more than any single input. It’s why accurate evidence for sale prices and build costs matters so much, and why an appraisal is only as good as the person preparing it.
Testing the risks
A good appraisal doesn’t stop at one answer. It tests what happens if things change: build costs rise 10%, sales take six months longer, or interest rates go up. This “sensitivity analysis” shows how much room for error the scheme has before it stops working.
When Do You Need a Development Appraisal?
- Before buying a site: to work out what you can afford to offer, and how far you can go in negotiations
- When selling land: landowners use appraisals to understand what a developer can realistically pay, so they don’t undersell or overprice
- When raising finance: lenders want to see that the scheme makes a sensible profit with room for error
- When converting a building: for example turning offices or a former shop into flats, where the costs can be hard to predict
- During planning: when a scheme’s viability affects how much affordable housing or Section 106 contribution it can support
- When setting up a joint venture: so landowner and developer agree how value is shared
Development Appraisals and Planning Viability
In planning, appraisals are used to test whether a scheme can afford the council’s policy requirements, such as affordable housing and infrastructure contributions.
Under national planning guidance, a scheme that meets the requirements of an up-to-date local plan is assumed to be viable. A developer who wants to provide less than policy requires has to justify why, usually with a viability assessment. Councils accept these in specific circumstances, such as unusual site costs or a type of scheme the local plan didn’t test.
Two things are assessed differently in a planning viability appraisal:
- Land value is based on a “benchmark land value”: the existing use value of the land plus a premium that would persuade a reasonable landowner to sell. It isn’t simply what the developer paid. Overpaying for land is not a reason to cut affordable housing.
- Developer’s profit is usually assumed at 15% to 20% of GDV, as set out in government guidance.
Viability assessments in planning are normally made public, and the council will usually have them independently reviewed. That makes it essential that the figures are realistic and well evidenced. RICS publishes a professional standard on assessing viability in planning, which our surveyors follow.
How Rory Mack Associates Can Help
An appraisal is only as good as its inputs. Our Chartered Surveyors and RICS Registered Valuers combine local market evidence with years of experience on residential and commercial schemes across Stoke-on-Trent, Staffordshire, Cheshire and Shropshire.
We help developers, landowners, investors and lenders to:
- Assess what a site is worth before making or accepting an offer
- Test the profitability of a scheme, including sensitivity analysis
- Prepare viability evidence to support planning applications
- Value completed schemes for funding or sale
Find out more about our development appraisal service in Staffordshire, or see our commercial valuations for completed buildings. If you’re considering a site as an investment, our guide to investing in commercial property is a useful next read.
Summary
A development appraisal tests whether a project makes financial sense. Using the residual method, it starts with the gross development value, deducts every cost and the developer’s profit, and leaves the residual land value: the most you can pay for the site. Small changes in sale prices or build costs can swing the land value dramatically, so accurate evidence and sensitivity testing are essential. Appraisals are used to buy and sell land, raise finance and support planning applications, where viability is judged against a benchmark land value and a developer’s return of around 15% to 20% of GDV.
Planning a development or weighing up a site? Speak to our surveyors on 01782 715725.
Frequently Asked Questions
GDV stands for gross development value. It’s the total value of a development once it’s finished, based on what the completed units would sell or let for. It’s the starting point of a development appraisal, before any costs are deducted.
It’s a way of valuing land with development potential. You take the gross development value of the finished scheme and deduct all the costs of building it, including the developer’s profit. The amount left over, the residual, is what the land is worth for that scheme.
It depends on the risk of the scheme, but government planning guidance says 15% to 20% of GDV may be a suitable assumption for viability testing. Lower-risk elements, such as affordable housing with a guaranteed buyer, may justify a lower return. Lenders often expect to see a similar margin.
A valuation gives the current market value of a property as it stands. A development appraisal looks forward: it estimates what a site could be worth once developed, and works back to what the land is worth today. Many projects need both, for example a valuation for the lender and an appraisal to test the scheme.
Not always. If your scheme meets all the local plan’s policy requirements, viability is normally assumed. You’ll usually need a viability appraisal if you want to provide less affordable housing or lower contributions than policy requires, and you’ll need to justify why.
