Recording house areas: separate living space, cellar, attic and garage

Which area is needed for which purpose?

A figure in square metres is usable only with its reference basis. Plot area describes the land, a building area describes the structure, and a room schedule describes particular internal areas. Energy-related areas and areas used to estimate construction costs may use different boundaries again. When using someone else's calculation, therefore request its definition and check which rooms and components it includes.

§ 17 MRG, for example, contains a usable floor area definition for its tenancy-law scope. It excludes, among other things, certain cellar and attic rooms that are not suitably fitted out, as well as open balconies and terraces. This rule is not a universal calculation requirement for every detached-house sale. Record whether a figure comes from such a legal calculation, a technical area standard or an agreed valuation basis.

Foundations: RIS [1]

An area worksheet that can be checked

Assign clear room numbers on each floor and transfer them to the floor plan. Alongside the area, write the plan description and observed use. Add the measurement date and source: approved plan, later schedule or current measured survey. When measuring, retain the individual dimensions so that a third party can trace the total. Mark inaccessible areas rather than replacing them with an apparently precise figure.

Assess cellars, attic rooms and garages individually

A cellar may be used for storage, as a workshop, as a plant room or otherwise. Document access, natural light, room height, moisture and fittings without deriving a building-law status yourself. A heated hobby room does not become substantiated living area merely because it has a radiator. For attic space, roof slopes, genuinely usable areas and access also matter. Do not use a foreign formula for sloping ceilings without clarifying the Austrian calculation basis.

A garage is recorded separately with its parking capacity and usability. Being fully enclosed does not make it living space. The Vienna Building Code requires use in accordance with approval. For converted ancillary rooms, comparison with the building records is therefore decisive. Plans can be obtained through MA 37; missing or conflicting details are translated into a specific question to check.

Foundations: RIS [2] · Stadt Wien [3]

What if three documents state three different totals?

First compare the areas included. Often much of the difference disappears once the cellar, terrace or garage is shown separately. Then check whether wall areas, stairs or later alterations were treated differently. Only once the definition and scope match does any remaining difference become a genuine measurement or calculation question.

If a discrepancy is material to the decision, commission a traceable measured survey. The instruction should specify the calculation basis and separate areas required. Retain old values with their sources. Do not silently replace an earlier figure with the largest new number. A reconciliation is valuable for the dossier: old total, ancillary areas removed, corrected individual dimensions and a new clearly labelled total.

How areas enter the house comparison

For a comparison, numerator and denominator must match. If a house's purchase price includes land and a garage, the calculated price per square metre of living area must not be treated as purely a building price. A house with a large cellar and little garden also has different features from one without a cellar on a large plot, even if the living area is the same.

Ancillary areas do not become worthless because they remain outside a living-area total. Their significance depends on usability, condition and demand. Include these characteristics in a comparison matrix. A blanket conversion of every square metre of cellar into a fixed proportion of living area obscures differences. If a valuation uses weighted areas, it must explicitly explain the factors, purpose and market basis.