August 20, 2026

Property Development GDV: How to Value a Site Before You Buy

In Property Development, knowing what a completed scheme is likely to sell for is essential before agreeing a price for the land. This figure is known as the Gross Development Value, or GDV. It drives the viability appraisal, informs the maximum land bid and helps prevent costly decisions based on optimism rather than evidence.


A site may appear attractive because of its location, size or apparent potential. However, it is only a viable Property Development opportunity if the expected sale value can cover the build costs, development costs, profit requirement and land purchase price.


Table of Contents

What Is Gross Development Value in Property Development?


Gross Development Value is the total expected sales value of a completed development. Put simply, it is the amount all completed homes should sell for once they are built and ready for sale.


For example, if a proposed Property Development scheme contains four houses and each house is expected to sell for £400,000, the GDV is:


4 homes × £400,000 = £1,600,000 GDV


GDV is not the amount available to spend on land. It is the starting point for working backwards through the appraisal. From the GDV, a developer must deduct profit, construction costs and all other development costs to establish what is left for the site.

Why GDV Is the Starting Point for a Viability Appraisal


Every major decision in Property Development flows from the end value. If the GDV is overstated, the land value will also be overstated, potentially turning a marginal scheme into a loss-making one.


A simplified residual land value calculation is:


GDV − developer’s profit − total development costs = residual land value


The residual land value is the maximum amount available to acquire the land, before considering the need for caution, negotiation and any site-specific uncertainties.


Worked example: a viable site

Assume a scheme has a GDV of £1,600,000. A 25% developer’s profit allowance is £400,000. If total build and development costs are £1,000,000, the calculation is:


  • GDV: £1,600,000
  • Developer’s profit at 25%: £400,000
  • Total costs: £1,000,000
  • Residual land value: £200,000


In this example, the scheme can support a land value of £200,000. Whether it remains a sensible purchase depends on the accuracy of the sales evidence and cost assumptions.


Worked example: an unviable site

Using the same GDV of £1,600,000 and profit requirement of £400,000, suppose total costs rise to £1,240,000:


  • GDV: £1,600,000
  • Developer’s profit at 25%: £400,000
  • Total costs: £1,240,000
  • Residual land value: minus £40,000


A negative land value indicates that the scheme does not work on those assumptions. In practical terms, the development costs and required return exceed the expected sales proceeds. For a Property Development business, this is a clear signal to reconsider the scheme or walk away.

How Much Profit Should a Property Developer Allow?


A commonly used target for a straightforward scheme with full planning permission is a developer’s profit of 25% of GDV. This is not simply a reward for completing the project. It is a buffer for the risk inherent in Property Development.


Unexpected costs can arise during construction, sale prices can change and project timescales can move. A sufficient profit margin helps absorb these risks. Lenders also generally expect a substantial margin, with approximately 22% to 23% of GDV often cited as a level they may want to see. Targeting 25% provides more headroom.


The appropriate profit assumption depends on the risk profile of the deal. A site bought with planning permission and all relevant approvals in place is different from a site where planning permission still needs to be secured.


Planning gain and profit uplift

Buying a site without planning permission can create additional value if permission is later obtained. In that case, the developer is helping move the land from its existing value to a higher value with planning consent.


That uplift should be recognised in the deal structure. Where the landowner benefits from planning gain, it may be appropriate for the developer to share some of the uplift while still retaining enough profit for taking on the work, risk and cost of securing permission.


This is why Property Development appraisals should distinguish between a straightforward build-out profit and the additional value created through planning.

How to Estimate GDV Using Comparable Evidence


GDV should be based on evidence from the local market, not on a hoped-for selling price. The most useful approach is to gather several types of comparable property data and form a cautious, informed judgement.


For a proposed Property Development scheme, aim to review three categories of comparables:

  1. Recently sold homes: Evidence of what buyers have actually paid.
  2. Current asking prices: Evidence of how competing homes are being marketed.
  3. New-build homes: Evidence of the premium buyers may pay for a newly built property.


Recently sold prices are particularly important because they reflect completed transactions. Current listings are useful context, but an asking price is not proof of the price a buyer will ultimately pay.


Match the comparables to the homes you intend to build

Comparables should resemble the proposed homes as closely as possible. Consider the number of bedrooms, house type, condition, location and size. A detached four-bedroom house should not be treated as a direct match for a smaller semi-detached home simply because both are nearby.


For a small Property Development project, it is often easier to identify a clear target house type. Larger schemes may involve a mix of units, so the appraisal may require separate GDV estimates for each house type before combining them.


Start local, then widen the search carefully

Begin with the site postcode and a tight search radius. If there is insufficient evidence nearby, widen the search area gradually. The aim is not to find the highest-priced property within reach. It is to find genuinely relevant evidence that reflects the market your completed homes will enter.


New-build comparables can be harder to find in some locations. If suitable new developments are further away, assess carefully whether they serve a similar market and offer a comparable type of home.

Why Price Per Square Metre Matters


Price per square metre helps compare homes of different sizes on a more consistent basis. It is particularly useful in Property Development when estimating the sale value of a proposed house that does not exactly match any existing comparable.


The basic calculation is:


Sale price ÷ internal floor area in square metres = price per square metre


For instance, if a house sold for £400,000 and has an internal area of 154 square metres, its approximate value is:


£400,000 ÷ 154 sq m = approximately £2,597 per sq m


Repeat this calculation across multiple comparables. The resulting range will give a more useful basis for judging the likely value of the proposed homes.


Where to find internal floor area

Property listings often include floorplans, and these may state the total internal area. If the area is not shown, an Energy Performance Certificate can provide the floor area for an existing property.


When assessing new-build listings, developers or selling agents may be able to confirm the internal square metreage. If only room dimensions are supplied, use the plan carefully to estimate the internal area.


Be careful with garages. A garage can contribute to buyer appeal, but it should not automatically be valued at the same rate per square metre as the main living accommodation.

How to Choose a Sensible GDV From Your Comparables


Do not rely on a simple average without considering the quality of each comparable. A professional Property Development appraisal requires judgement.


Suppose the evidence suggests that established resale homes are worth around £2,600 per square metre, while relevant new-build homes are marketed closer to £3,000 per square metre. It may be unreasonable to apply the full £3,000 figure without strong evidence that the proposed homes will achieve it.


A cautious assessment could use a figure somewhere between the resale and new-build evidence, such as £2,700 or £2,800 per square metre. The exact selection should reflect the quality, specification, location and competition for the planned homes.


When in doubt, lean towards the conservative end of the evidence. An appraisal that only works at the most optimistic GDV is not a resilient appraisal.

A Practical GDV Checklist for Property Development


Use this process before making or increasing an offer on a site:

  1. Define the proposed scheme. Identify how many homes may be built and the likely size and type of each.
  2. Find local sold comparables. Focus on recent, relevant sales in and around the site postcode.
  3. Review active competition. Check current asking prices for similar homes that may compete with the finished scheme.
  4. Find new-build evidence. Identify whether new homes in the wider area achieve a meaningful premium.
  5. Record price and floor area. Calculate price per square metre for each credible comparable.
  6. Make a cautious GDV judgement. Select a realistic sales rate rather than the highest available figure.
  7. Calculate total GDV. Apply the chosen value to the proposed internal area or expected sale price of each unit.
  8. Deduct profit and costs. Work backwards to identify the residual value available for land.
  9. Test the result honestly. If the land value is too low or negative, do not force the deal to work.

Common Property Development Valuation Mistakes


Falling in love with a site

One of the biggest risks in Property Development is becoming emotionally invested in a site. After spending time researching planning, comparables and costs, it can be tempting to adjust assumptions until the appraisal produces the desired result.


This approach is dangerous. The numbers should determine whether a site is viable. The site should not determine the numbers.


Using only asking prices

Asking prices are useful, but they are not confirmed sales. A listing may be reduced, withdrawn or sold for less than its advertised price. Use asking prices alongside recent sold evidence, not instead of it.


Ignoring the new-build premium

New homes can attract a premium, so resale values alone may understate GDV. Equally, assuming an automatic premium without checking local new-build evidence can overstate the appraisal. Both resale and new-build data matter.


Comparing unlike properties

A larger detached home, a smaller semi-detached home and an outdated refurbishment project may all produce very different price-per-square-metre figures. Select comparables that genuinely reflect the proposed product.


Forgetting that costs can change

GDV is only one side of the viability equation. A strong sales estimate cannot rescue a scheme with unrealistic build or development costs. Keep the profit allowance intact so the Property Development project has room for uncertainty.

When Should You Walk Away From a Development Site?


Walk away when the evidence-based GDV, less realistic costs and an appropriate profit margin, does not leave enough value to acquire the site. A negative residual land value is an obvious warning sign, but a very thin margin can also be unsuitable.


Walking away is not a failure. It is a core discipline in Property Development. Protecting capital by rejecting an unviable deal is usually more valuable than securing a site at any cost.

Key Takeaway


A reliable GDV assessment is the foundation of a sound Property Development appraisal. Research recently sold homes, current listings and local new-build stock. Convert credible comparables into price-per-square-metre evidence, make a cautious valuation judgement and work backwards from GDV to determine what the site is truly worth.


If the appraisal does not support the land price while retaining realistic costs and a proper profit margin, the disciplined decision is to renegotiate or move on.

Frequently Asked Questions

What does GDV mean in Property Development?

GDV means Gross Development Value. It is the total expected sale value of all homes in a completed development.

How do you calculate GDV for a housing development?

Estimate the likely sale price of each completed home using comparable evidence, then add those expected sale prices together. Alternatively, apply a cautious price per square metre to the planned internal area of each unit.

What is a good profit margin for Property Development?

For a straightforward development with full planning permission, a 25% profit margin based on GDV is a useful target. It provides a buffer for risk and is above the substantial margin often expected by lenders.

Should new-build homes be valued higher than older homes?

New-build homes can command a premium, but this should be supported by evidence from relevant local new-build schemes. Do not assume the highest new-build price is achievable without comparable support.

What does a negative residual land value mean?

It means the anticipated GDV is insufficient to cover the required profit and total development costs. On those assumptions, the site is not viable at a positive land price.

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