Investment approach
Valuing a unique house with no comparables: three approaches
A house with no comparables has no single valuation, only a range from three approaches. In the worked example, cost gives 3,35 M€, comparison on a thin sample 3,1–4,4 M€, and the seller asks 4,8 M€.
When there are no comparable sales, a house is valued not with one number but with a range from three approaches: comparison, cost and the residual method. The comparison method in Orden ECO/805/2003 (the ministerial order on property valuation) requires data on at least six transactions or offers (art. 21), and for a unique house that condition is usually not met. A unique house here means a property for which no comparable sales can be found by area, size and style. Below: a table of approaches, the bank's rule and a worked calculation.
What are the three approaches and when does each work?
| Approach | What it calculates | Condition in Orden ECO/805/2003 | Weak point for a unique house |
|---|---|---|---|
| Comparison | The price from comparable properties with adjustments | At least six transactions or offers and a representative market (art. 21) | With no comparables the condition is not met |
| Cost | Replacement cost: land, construction, necessary costs, less depreciation (art. 18–19) | Applies to any building (art. 17) | Does not measure the value of uniqueness |
| Residual | The value of land from the price of a future project | Land and buildings in design, construction or refurbishment (art. 34) | For a finished house it works as a check on the plot price, not the house |
Replacement cost includes land, construction by contract and necessary costs, but not the developer's profit or financial and commercial costs (art. 18). In a straight-line calculation, depreciation is measured over the building's useful life: the valuer sets it, but for residential buildings it cannot exceed 100 years (art. 19). For buildings of historical or artistic character, the special value of the elements that give that character is added to the calculation (art. 18.3).
Valuation to RICS standards (the Red Book) runs under a separate regime: it is not tied to Orden ECO/805/2003 and is commissioned for a specific purpose. Which report the bank needs and which one serves a pricing decision, ask the bank and the valuer.
What does the bank do when there are no comparables?
If the valuation is made for the purposes of art. 2.a (in the wording from 12.08.2025, mortgage loans that form part of the cover for a bank's mortgage bonds), for an owner-occupied or vacant house there is a ladder: comparison first; if that is impossible, updating of rental income; and if that is impossible too, the appraised value cannot exceed the net replacement cost (art. 45.2.c). For the buyer the conclusion is simple: a bank valuation of a unique house may come in below the transaction price, and the difference has to be covered with own funds. Which methodology the bank uses to value your loan and how much it lends is the bank's decision, and you check it before signing the arras (deposit contract), not after.
What does the range look like in an example?
Worked example, not a forecast. A house of 600 m², plot of 3 000 m², 20 years old. All figures are assumptions; the building's useful life is taken as 100 years (the maximum for residential use under art. 19) and depreciation is straight-line.
| Cost approach | Amount, € |
|---|---|
| Land (assumption) | 1 800 000 |
| Construction 600 m² × 2 800 | 1 680 000 |
| Necessary costs 15% | 252 000 |
| Gross replacement cost | 3 732 000 |
| Depreciation: (1 680 000 + 252 000) × 20 / 100 | 386 400 |
| Net replacement cost | 3 345 600 |
Comparison on a thin sample: three comparables after adjustments give 5 200, 6 100 and 7 400 € per m², that is 3 120 000, 3 660 000 and 4.44 M€, averaging 3.74 M€. The spread between the extremes is 35% of the average. This is a benchmark, not a valuation: three comparables is fewer than six.
| Benchmark | Amount, € | The 4 800 000 ask is higher by |
|---|---|---|
| Net replacement cost | 3 345 600 | 43,5% |
| Comparison, minimum | 3 120 000 | 53,8% |
| Comparison, average | 3 740 000 | 28,3% |
| Comparison, maximum | 4 440 000 | 8,1% |
The gap between the ask and the top of the range is the price of uniqueness. There is nothing to measure it with, but you can decide whether you are willing to pay it, and name your walk-away price before the negotiation.
How do you use the range in negotiation?
- Ask for three figures separately, not one final number: replacement, comparison on the sample, and the valuer's conclusion.
- Do not take area averages as a comparable. In the registrars' statistics for the second quarter of 2026, the average price of registered housing in the city of Barcelona over the last four quarters is 5 045 €/m² (ERI, the registrars' property statistics), but that is the average across all registry transactions, not for a villa of unusual architecture.
- Check the land separately. If the house stands on a large plot, the land value under the residual method gives a floor of reference.
- Build in a cushion. How project models do it is explained in the article on the margin of safety, and on the gap between asking and closing prices in the piece on the price difference.
- Tie the purchase to the valuation result in the arras terms. A lawyer chooses the wording.
The value declared in the documents is also checked by the tax authority: see the article on the comprobación de valores (tax value verification).
Who is this valuation not for?
Houses that do have comparables: the comparison method is enough there, and three approaches only add noise. Properties whose value lies in authorship or history: the cost approach will understate the price, and the special value of the elements has to be set by the valuer's expert judgement. And anyone looking for one fair number: a unique house has none, only a range and the buyer's decision.
You can run your property through the property valuation tool and the investor calculator.
Questions and answers
How do you value a house if there are no comparables?
You work out a range from three approaches: cost (replacement cost), comparison on a thin sample, and residual for the land. The result is not one number but a range within which the buyer makes a decision.
How many comparables does the comparison method need?
Under Orden ECO/805/2003, information on at least six transactions or offers and a representative market. The order is mandatory only for the purposes in its art. 2, but it works as a yardstick for any deal.
Can the bank value the house below the transaction price?
Yes. If the bank values under Orden ECO/805/2003 for the purposes of art. 2.a, then for a house with no comparables and no rental market the valuation is capped at net replacement cost, which can be below the contract price. The buyer covers the difference.
Does an RICS valuation replace the bank's valuation?
No. An RICS report is commissioned for a specific purpose, and the bank may require its own valuation under its own methodology. What you need in your case, clarify with the bank in advance.
Where do you find prices to compare?
In closed transactions and in registry data. Registry averages by province give the scale but not a comparable, so for a unique house they serve as background, not as a price.
