- Existing rent, lettable vacancies and building development each receive separate scenarios.
- An idea for floor space becomes a testable development assumption only through rights, planning and project costs.
- The same future income must not be counted both in the existing position and again as additional potential.
Scenario one: what does the documented existing position contribute?
The starting point is the units, agreements and payments in place on the valuation date. Use transparently prepared income figures and the associated owner costs. Major known works are explicitly included in the chosen model. Hopes for higher occupancy or additional floor space do not yet belong in this starting column.
A low existing rent does not permit an arbitrary jump to an asking rent. The contractual position, rent setting and timing requirements must first be checked. The MRG contains different scopes of application and rules; different bases may be relevant within the same building. Therefore document the professionally confirmed scope for change for each unit instead of assuming a uniform uplift to the building's rent.
Foundations: RIS – Bundeskanzleramt [1]
Scenario two: what can be achieved with available vacant units?
For each vacant unit, record the possession and use status, the use documented under building law, technical condition and necessary work. Being free of a current tenancy does not automatically mean being immediately lettable. Renovation needs, unclear use or a missing system inspection can delay the start and increase funding requirements.
The future rent needs justification from a legal review and suitable market data. Add start-up costs, expected marketing time and a credible commencement date. Keep one-off vacancy costs separate from subsequent recurring operating costs. This reveals whether the additional annual rent requires short-term liquidity and from when it could actually help fund the property.
Foundations: RIS – Bundeskanzleramt [1]
Scenario three: what does an attic conversion require?
First check whether the area in question is legally available. The land register, agreements and existing use rights must be considered together. Then examine the approved existing building and current planning rules. In Vienna, planning documents consist of a plan and text. The map overview is an information aid; binding provisions and specific possibilities for use must be clarified using the relevant documents and professional advice.
A floor-space design must be compatible with load-bearing capacity, access, fire safety, building services and the other requirements of the specific project. For building permits, the city lists building plans, owner consents and structural evidence among the required documents. A theoretical attic area therefore does not automatically equal approvable living area or lettable usable floor area. The planning professional clarifies the required procedures and evidence for the specific property.
Foundations: Stadt Wien – Stadtplanung [2] · Stadt Wien – MA 37 [3]
Assess the project stage reached rather than a general chance of success
Describe progress in verifiable stages: idea, preliminary technical review, coordinated design, submission, required permission, secured implementation and completed use. Each stage requires specific documents. A submission does not prove permission has been granted, and permission confirms neither current building costs nor financing. The list should identify the next missing piece of evidence.
Do not assess permission questions using an invented success rate. Instead, show a scenario subject to stated conditions and a scenario without implementation. Add which costs might also arise if planning is abandoned. This reveals which expenditure serves clarification and which larger capital commitment comes only after the next project stage is reached.
| Scenario | Income basis | Requirement | Additional outlay |
|---|---|---|---|
| Existing position | Documented current agreements | Reconciliation of agreements and costs | Known maintenance |
| Use vacancies | Justified new rent assumptions | Availability and lettability | Adaptation and start-up period |
| Develop the attic | Planned additional use | Rights, planning, permission and implementation | Construction, ancillary costs, time and financing |
Bring together all costs and additional benefits
Set all project-related expenditure against the additional income. This may include planning, permission, construction, technical adaptations to the existing building, marketing and time-related costs. Also show possible disruption to existing units. Choose a consistent analysis with appropriate timings and avoid comparing an immediate expense with an undiscounted, unlimited series of rent receipts.
Potential is not added twice: if future attic rents are already included in an overall cash-flow model, the project value derived from them must not be added on top again. The same applies to vacancies already modelled as relet. A professional assessment is also needed of which stage of development the market would recognise on the valuation date; project profit and today's property value are different measures.
Foundations: RIS – Bundeskanzleramt [4]
Fictional decision case: vacant apartment first, further review of the attic idea
An imagined building with a vacant apartment and an attic area that has not yet been converted. No actual areas or Vienna market prices are asserted.
- A return-of-possession report and existing-layout plan are available for the vacant apartment. An assessment identifies limited work; a quotation and tenancy-law review still need to be obtained.
- Only a sketch exists for the attic. Availability, current development provisions and load-bearing capacity remain unresolved. No additional rent from it enters the existing-position calculation.
- The owners first set a budget for the vacant apartment's missing evidence. For the attic, they commission a limited preliminary review with a clear question and a cost cap.
- The valuation receives three separate states, including the requirements still outstanding; favourable results from both projects are not automatically combined.
The sequence follows the current state of knowledge. Potential that sounds larger is not necessarily the next sensible and affordable measure.
Your next assessment steps
Record what you have already clarified and which documents you still need.
Existing-position calculation without unverified jumps in income
This forms the shared comparison basis for all scenarios.
Where can I obtain the supporting information?
Compile it from the rent roll and owner costs.
Evidence of availability and use
This shows whether the planned area can actually be used.
Where can I obtain the supporting information?
Have agreements, the land register and the building file reviewed together.
Current planning document including its text section
This provides the project's planning-law basis.
Where can I obtain the supporting information?
Use Vienna's information system and have specific questions clarified professionally.
Project sheet with costs, timing and outstanding evidence
This connects potential benefits with the requirements for implementation.
Where can I obtain the supporting information?
Coordinate it with planning, legal review and valuation.
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Sources and date
The following sources support this main article. For your specific property, current documents and the applicable conditions matter.
- RIS – BundeskanzleramtTenancy Act: scope of application and rent rules
- Stadt Wien – StadtplanungLand-use zoning and development plan information system
- Stadt Wien – MA 37Documents required for a building permit
- RIS – BundeskanzleramtProperty Valuation Act § 5: income approach
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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