- Identify data gaps precisely: a missing sale price, missing attributes and unsuitable cases are different problems.
- Widen the comparison area on the basis of demonstrable similarity and justify every adjustment.
- Supplementary approaches must provide new insight; their results should not be averaged without scrutiny.
What kind of comparison is actually missing?
A public listing may provide many photographs but no achieved purchase price. Transaction information may include a price but reveal too little about condition or rights. Finally, a well-documented sale may be materially unsuitable, for example because of a very different plot or a particular use. Record these three cases separately before collecting more data.
§ 4 LBG describes comparison using prices actually achieved for comparable properties and taking account of differences that affect value. For your worksheet, this means giving price type, date, plot, living area, ancillary areas, condition and legal particularities their own fields. A missing field is marked as unknown. It is not replaced with a plausible guess simply to make the case fit the calculation.
Foundations: RIS [1]
Widen the search in traceable steps
Before widening the search, decide which attributes are crucial for your house. For a small terraced house, building type and plot use may matter more than a large villa nearby. For a house on a slope, accessibility and usable outdoor areas may be particularly relevant. Proximity alone does not guarantee comparability.
Then expand one dimension at a time: period, geographical search area or range of attributes. Document why the additional cases help and which differences remain. Older transactions need a justified time adjustment. A listing from a different market segment cannot reliably be made suitable by applying an arbitrary percentage discount. Cases with key attributes unknown may provide context, but should not support an apparently precise result.
Foundations: RIS [1]
What benefit does each additional piece of information provide?
The next piece of research should reduce a specific uncertainty. If the main gap concerns the land component, more suitable plot information will help. If the building's condition is unclear, a technical assessment provides more benefit than further listings. The following matrix outlines a workflow; it does not automatically assign an approach to a house.
| Open question | Supplementary basis | Limitation |
|---|---|---|
| Which sales are truly similar? | Detailed comparison matrix and transaction research | Prices without property details remain of limited significance |
| How much does the land contribute? | Suitable plot cases and a review of use | Undeveloped land cannot simply be equated with the developed property |
| How should the building be assessed? | Building component assessment and a transparent cost-based analysis | Construction costs are not an established market price |
| Is an income-based analysis relevant? | Documented use, legal requirements and market-based income assumptions | An invented rent does not resolve the data gap |
| Is the order of magnitude plausible? | Suitable regional statistics with a stated methodology | An aggregate cannot replace an individual property valuation |
Foundations: RIS [2] · RIS [3] · Statistik Austria [4]
What other approaches can provide
A cost-based analysis can make assumptions about land, the building and its condition visible. It requires a suitable cost basis and professional assessments; its result must reflect the market. Where use is income-driven, an income-based analysis may supplement it. The choice depends on the specific property and purpose, and on the quality of the available evidence.
§ 7 LBG provides for professional selection of the approach and derivation of value with regard to market activity. An average calculated from several approaches is not a justification in its own right. If results diverge, look for the cause: different floor areas, a different condition, contradictory assumptions about use or an encumbrance treated differently. Averaging does not make a poorly supported second calculation more robust.
A robust assessment identifies its uncertainties
Statistik Austria's average property prices represent regional price levels using a described data and modelling approach. Transactions from previous years also feed into the calculation for a target year. Such figures help provide context, but are not a current list of fully comparable neighbouring houses. Check the year, property group and size category before using them.
Ask for the main assumptions and their effect to be stated in the result. A range should arise from justified alternatives, rather than simply applying an arbitrary percentage around an estimate. The decisive question for action is: what additional information would actually narrow the range? If an unresolved attic conversion materially changes the result, checking it is the next step, even if many more listings have since become available.
Foundations: Statistik Austria [4]
Fictional case: an unusual house and five unsuitable listings
An explicitly invented house has a large sloping plot, a small living area and a steep access road. The five available listings concern level plots; no achieved purchase price is known for any of them.
- The five cases are labelled as observed asking prices. They provide indications of competing properties, but no reliable direct transaction comparison.
- The research specifically seeks houses with similarly usable plots and documents geographical and time differences.
- A supplementary analysis examines the land and building. The access road is described objectively and assessed professionally, without applying an invented standard discount.
- The result states which uncertainty arises from missing transactions and which from unresolved property attributes.
Quality comes from an assessment process that can be explained. A larger number of unsuitable listings would not have solved the underlying data problem.
Your next assessment steps
Record what you have already clarified and which documents you still need.
Record price type and data gaps
Is the figure a purchase price, an asking price or a model output?
Where can I obtain the supporting information?
Review all cases used so far in a matrix.
Define the crucial comparison attributes
Which characteristics limit transferability?
Where can I obtain the supporting information?
Assess the house profile and plot use.
Ask for the choice of method to be explained
What additional insight does each analysis provide?
Where can I obtain the supporting information?
Add the data basis and justification of the approach to the valuation brief.
Identify the greatest remaining uncertainty
Which next check could improve the result?
Where can I obtain the supporting information?
Prioritise approximations and unresolved property attributes separately.
Reading and checking are possible without signing in. Your saved checklists are private under My area. The selection does not confirm a professional assessment of your property.
Sources and date
The following sources support this main article. For your specific property, current documents and the applicable conditions matter.
- RISProperty Valuation Act § 4: sales comparison approach
- RISProperty Valuation Act § 6: cost approach
- RISProperty Valuation Act § 7: choice of valuation approach
- Statistik AustriaAverage property prices: description and user guidance
Editorial date: 11/09/2026. Examples explain relationships and do not contain an individually prepared property valuation. Editorial work and sources.
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