Valuing existing buildings, demolition issues and ground contamination

What economic role does the existing building play?

First record what is actually present and how it is used: main buildings, outbuildings, basements, paved areas, tanks and service lines. Add the building file, approved existing plans, technical assessments and any occupancy agreements. A vacant house may still be usefully occupied; a hall that appears intact may require substantial adaptations for another use.

Examine at least the obvious alternatives: continued use of the existing structures, targeted adaptation or development after demolition. Each alternative receives its own requirements and costs. Do not add a full building value to the unreduced value of a development plot that is already cleared. Equally, usable existing income must not disappear merely because an attractive new-build idea exists.

Can demolition be assumed possible at all?

In Vienna, particular care is needed with conservation zones, building restrictions and buildings erected before 1 January 1945. The city describes special requirements for confirmation, notification and, where applicable, permission. For a listed property, a separate review with the Bundesdenkmalamt is also required. A neglected appearance or marketing description as a demolition property does not replace these procedures.

Have the specific procedural route clarified with the building authority and an authorised planning professional. Preparation should include building age, existing plans, historical documents and current photographs. If demolition is to rely on particular legal requirements, that precise justification must be examined. Until then, the assumption of a cleared building site remains a conditional scenario. Permitted removal of existing structures also does not confirm a subsequent new-build project.

Foundations: Stadt Wien – Architektur und Stadtgestaltung [1]

Investigate buildings and ground separately

For buildings, the concern is materials and components: which substances are present, where are they located and how do they affect demolition, separation and disposal? The City of Vienna describes surveys of hazardous and interfering substances, including sampling. The necessary investigation scope must be determined professionally according to the project and applicable rules. Opening up materials yourself without suitable expertise does not provide a reliable basis.

For the ground, historical uses, deposits, fill and possible pollutant inputs are relevant. A former workshop raises a specific question; it does not yet prove contamination. Conversely, an unremarkable surface is no all-clear. Geotechnical properties such as load-bearing capacity and groundwater must be considered alongside chemical contamination. A laboratory report on one building material does not answer these ground-related questions.

Foundations: Stadt Wien – Prüf-, Inspektions- und Zertifizierungsstelle [2] · Umweltbundesamt / Altlastenportal [3]

What does an entry in the contaminated sites portal mean?

The contaminated sites portal shows different stages of investigation and assessment. Read the information for the specific site, not just the map colour. The Umweltbundesamt expressly explains that plots may also be contaminated by current or other historical uses. The absence of an entry therefore does not establish comprehensive freedom from pollutants.

Save the site information with the date and associated available reports. Add historical plans, information on former businesses and previous investigations. These documents enable a qualified specialist to decide which sampling is appropriate for the intended use or excavation. A general cost contingency does not replace investigation of a specific indication.

Foundations: Umweltbundesamt / Altlastenportal [3]

How does an assessment become a useful cost assumption?

Request quotations with identifiable quantities and boundaries: building demolition, foundations, basements, tanks, separation, transport, disposal, backfilling and protection of adjoining structures. Record which analyses and waste-disposal classifications underpin the quotation. Mark items that can only be quantified after further investigation. Distinguish a robust quotation from an initial estimate.

For the valuation, it also matters who must undertake which measure and by when. Sale in the existing condition, handover after demolition and handover with guaranteed ground characteristics are different scopes of performance. Have legal cost and liability questions reviewed for the specific contract. Do not mechanically treat the cost of measures as an equal market discount: loss of use, time, remaining uncertainty and demand for the existing structures may also affect the result.