Residual Method vs. Comparison Method: Valuing land with development potential
Introduction
I recently read a valuation report on a parcel of land situated on the fringe of a suburban township. Low-cost houses dominate the township and its surroundings. The land fronts the main road and carries an agricultural title, but its location suggests development potential.
The valuer adopted a comparison-based valuation method, drawing on transactions involving nearby land — some recent, others dating back more than a decade. This raised a critical question: Should land with development potential be valued purely as agriculture, or should the residual method be considered?
The Valuer’s Approach
The report included a site plan showing the comparables used: their locations, transaction dates and price per acre. When I asked the valuer which comparable she relied on most, she pointed to a plot diagonally opposite the subject property with direct road frontage. The catch? That plot was transacted 10 years ago.
She explained that agricultural land in the area appreciated at about 3–4% per annum, and by compounding this growth rate, she arrived at the current market value. In her view, this was neither optimistic nor conservative but simply fair.
When I asked why she didn’t use the residual method, she replied:
- The land had no development approval.
- The title was agricultural, so she valued it as such.
- If she had used the residual method, she would face the challenge of deciding what present value factor to apply for the period needed to obtain planning approval.
Thus, she stuck with the comparison method.
My Reservations
I had doubts about relying on a transaction from 10 years ago. Land markets are dynamic, and compounding a growth rate assumes steady appreciation without accounting for market cycles, infrastructure changes or shifts in demand. Moreover, valuing purely as agriculture ignores the development potential — the very factor that makes such land attractive to investors.
At first, I felt discouraged. Low-cost houses dominate the township. If developed, the land seemed suitable only for more of the same. A simple residual calculation suggested the project would not be viable: the selling price of low-cost houses would not cover development costs, leaving no profit.
The Residual Method Explained
The residual method is designed precisely for land with development potential. It works by:
- Estimating Gross Development Value (GDV) — the total sales value of the completed project.
- Deducting Development Costs — construction, infrastructure, professional fees, authority charges, marketing, finance and contingencies.
- Subtracting Developer’s Profit — typically 15–25% of GDV.
- Arriving at Residual Land Value — the balance represents what a developer could afford to pay for the land.
This method captures the future potential of land, not just its present agricultural use. However, it requires assumptions about approvals, market demand and costs. It’s more speculative if approvals are not yet in place.
The Role of Market Demand Assumptions
Here lies the crux: the residual method cannot function without assumptions about market demand.
- To calculate GDV, you must determine:
- How many units can be built.
- What type of units (low-cost, medium-cost, luxury).
- What price those units will sell for.
Without demand, GDV collapses, and the residual value becomes meaningless.
But can we ever be certain about demand? Rarely. Demand is tested through:
- Comparable sales of similar developments nearby.
- Market studies (income levels, demographics, absorption rates).
- Developer experience in similar townships.
Even then, demand is probabilistic, not guaranteed. Valuers often hesitate to use the residual method unless approvals are in place. Nevertheless, assumptions about demand and estimating pricing can be speculative.
Demand must be analysed. If market demand for the approved property type is low, the Gross Development Value (GDV) drops significantly, lowering the residual land value. A lower demand assumption lengthens the sales timeline. A longer timeline increases compounded holding and construction interest costs, which are subtracted from the GDV.
In weak or unproven markets with questionable demand, a developer will want a higher profit margin to take on the project. This higher required return further reduces the amount they can afford to pay for the land. The residual method is sensitive to its inputs. Overestimating market demand and underestimating construction costs can lead to catastrophic financial losses.
Valuers typically use conservative assumptions, run sensitivity analyses and disclose assumptions clearly. The residual method is not about certainty. It is about testing viability under different scenarios.
The highest and best use of the land needs to be legally permissible, physically possible, financially feasible and maximally productive. If there is no demand for the approved development, the valuer may conclude that the approved plans are obsolete, and value the land based on an alternative, lower density or delayed timeline use.
The Surprise Twist
Just when I thought the land was destined only for low-cost housing, I spoke to a consultant working with developers in an area a few miles from the subject land. Their projects were further away from the city centre, yet they successfully built and sold medium-priced houses.
The consultant explained that many wealthy farmland owners lived near the subject land. They would be willing to buy medium-cost houses for their children. Since no one had yet built such houses in the subject area, the market was untapped.
Based on realistic medium-cost house prices, the residual calculation flipped: the project became viable, with substantial profit potential.
Of course, valuation practice will not rely on assumptions about these wealthy farmers unless they have committed to buy. Developers would be taking a risk. Yet the evidence from projects several miles further suggested that demand was real, even if not guaranteed.
Should the Valuer Have Factored Development Potential?
From a strict professional standpoint, the valuer was correct: without development approval, the land is legally agricultural. The comparison method is defensible, especially for formal reporting.
However, from an investment perspective, ignoring development potential misses the bigger picture. The residual method, even if used as a sensitivity analysis, would highlight the upside and the risks. Investors need to see both.
Thus, the best practice may be to:
- Value the land as agriculture (comparison method).
- Provide a residual scenario analysis to show potential if approvals are obtained.
- Disclose assumptions and limitations clearly.
Should Developers Take the Risk?
The key question is whether developers should risk building medium-cost houses in an area dominated by low-cost housing.
- Arguments for risk:
- Untapped demand from wealthy farmers.
- Evidence of successful medium-cost projects nearby.
- Potential for substantial profit if demand materializes.
- Arguments against risk:
- No guaranteed buyers.
- Higher construction costs compared to low-cost housing.
- Market perception that the area is “low-cost only”.
Ultimately, it comes down to developer appetite for risk. A cautious developer may wait for approvals and pre-sales commitments. A bold developer may seize the opportunity, banking on latent demand. But if a bold developer takes the plunge, he must be certain that he can complete the development. Otherwise, the project risks becoming an unfinished scheme that leaves purchasers in limbo. For buyers, this is a nightmare: they would still have to service their housing loans with no property in sight. Ensuring financial strength, construction capacity, and proper risk management is therefore just as critical as identifying demand.
A developer’s capacity to complete a project is not part of a formal valuation. What happens after, whether a developer succeeds or fails in delivering, lies outside the valuer’s professional scope.
Conclusion
This case illustrates the tension between formal valuation practice and investment reality. The valuer was right to use the comparison method given the agricultural title and lack of approvals. Yet the residual method reveals the land’s hidden potential and the risks of unlocking it.
For investors and developers:
- Don’t rely solely on past transactions, especially ones that are outdated.
- Use the residual method to test viability under different scenarios.
- Without formal approvals, development potential is about market insight, demand analysis and risk appetite.
In the end, valuation is not an exact science. It is a discipline rooted in evidence at a specific point in time, guided by professional judgment about what is reasonably knowable. Foresight here does not mean predicting the future. It means applying insight into local market movements, understanding the drivers of demand, and recognizing risks that are visible at the valuation date.
