Detached house construction costs per m² of gross floor area

Figures published in 2026 for a turnkey detached house run from about 1,900 to over 5,000 euros per square metre. Practically all refer to the Wohnfläche, the habitable area; most consumer sources are inclusive of value added tax; and the scope of works varies considerably.

The phrase "ab Oberkante Bodenplatte", from top of slab, deserves particular care. It appears frequently in prefabricated house offers and means that excavation, foundations, the slab itself and any cellar are excluded. Those items belong to cost group 300 and are therefore part of building cost, even when absent from the offer.

The following calculation converts a figure found online into a quantity comparable with professional benchmarks. Example: a house with 150 square metres of habitable area, without a cellar, offered at 3,400 euros per square metre of habitable area, gross of tax.

The starting figure of 3,400 and the result of 2,041 describe the same house. Between them lie no cost saving and no change of specification, only two arithmetic steps.

Note that the factor of 1.40 applies to a house without a cellar. For a house with a cellar and a converted roof space it runs considerably higher, because both storeys enter gross floor area in full and habitable area only in part or not at all. Using the wrong factor merely relocates the error. The documented orders of magnitude are set out in the article on reference areas.

The German market customarily distinguishes three levels. The classification is not normed, but the characteristics are consistent across sources.

Sources put the step from mid-range to high specification at an order of several hundred euros per square metre of habitable area. The increment falls mainly on bathrooms, floor finishes, windows and building services, that is on items fixed late in the construction sequence and therefore still liable to move during the works.

Practical consequence for cost planning: specification standard should be recorded in the cost framework not as an adjective but as a list of concrete decisions. Otherwise it cannot later be demonstrated which level underlay the estimate.

The cellar is the most expensive storey of a German detached house. Excavation, spoil removal, tanking against ground or pressurised water, foundations, drainage and insulation of the ground-bearing elements all fall within it. Sources put the additional cost of providing a cellar to a typical house in the order of several tens of thousands of euros, with wide variation by ground conditions, water table and sloping site.

Arithmetically the cellar acts in two directions, and this is the most common source of confusion on the subject. One effect concerns the cost, the other the reference area.

• Per square metre of habitable area it makes the house more expensive, because it raises the construction sum without contributing habitable area.
• Per square metre of gross floor area it makes the house arithmetically cheaper, because it greatly increases gross floor area and cellar storeys cost less per square metre than living storeys.

Both statements are correct and describe the same building. They show why a benchmark without a stated reference area is not a statement at all. To compare two designs, one with a cellar and one without, the reference area must be fixed and the conclusion phrased accordingly.

The ratio of thermal envelope area to heated volume determines how much expensive facade, roof and window area falls on a given usable area. External walls, roof and windows are among the most cost-intensive elements of the house.

A compact, roughly square form with a simple roof requires appreciably less envelope area than an articulated design with bays, dormers, set-backs and multiple roof planes for the same schedule of accommodation. The cost difference between the two generally exceeds the step between two specification levels.

The effect works twice over, because a smaller envelope also reduces insulation quantities and subsequent energy demand. At early design stages compactness is therefore the most effective cost lever available, and the only one that is practically impossible to correct later.

Which construction method is cheapest is the most frequently asked question and the least clearly answerable. The sources openly contradict one another: some list prefabricated houses as the cheaper option, others now place them above masonry construction.

The contradiction resolves once you look at what is actually being compared. The two figures refer to different areas.

The degree of prefabrication, the scope of works and the specification level differ between offers more than the construction method itself does. A prefabricated house in kit form and a turnkey masonry house are two entirely different purchases, even when both are presented as a square metre price.

Two statements do hold up. First, prefabrication shortens the construction period considerably, which reduces financing costs and, where the client is moving from rented accommodation, the period of double outgoings. Second, bespoke design raises ancillary costs while opening the widest scope on compactness, that is on the most effective cost lever there is.

The benchmark per square metre falls as the house gets larger. This is not peculiar to housing but a consequence of fixed cost degression: kitchen, bathrooms, heating plant, utility connections, staircase and site establishment arise largely independently of floor area.

Two houses of 110 and 180 square metres of habitable area with identical specification therefore differ noticeably in square metre price without either being more economically designed. Comparing two offers of different size through the square metre price systematically penalises the smaller house.

For cost planning this means a benchmark should always be used for the building size it was formed for. Datasets identify size classes for this reason. Anyone adopting a benchmark from a different size class should at least name the effect, even where they cannot quantify it.

The same mechanism explains, incidentally, why apartment buildings cost less per square metre than detached houses. The comparison between the two types is covered in the article on apartment building construction costs.

An offer described as turnkey typically excludes several items. The term is not defined by any standard and must be checked case by case.

• excavation, foundations and slab, where the offer runs from top of slab
• the cellar
• utility connections for water, drainage, electricity, gas and telecommunications
• external works, driveway, terrace, boundaries and planting
• carport or garage
• ancillary construction costs, meaning design, structural engineering, surveys, charges and setting out
• the site itself and its acquisition costs

The German term schlüsselfertig, turnkey, has no legal definition and describes no fixed scope of works. What governs is solely the specification attached to the particular offer. Two offers at the same square metre price can differ in scope by a six-figure sum.

For the classification of ancillary costs and their base, see the article on ancillary construction costs under KG 700. It also sets out which base each percentage sensibly refers to.

Going beyond the requirements of the German Buildings Energy Act, for instance to satisfy grant conditions, brings additional cost in insulation, windows, airtightness and plant. Orders of magnitude by element and the link to the funding landscape are covered in the article on additional costs for efficiency house and passive house standards.

• Residential construction costs in Germany
• Additional costs for efficiency house and passive house standards
• Reference areas: BGF, NRF and Wohnfläche
• Ancillary construction costs under KG 700
• Construction costs per m² in Germany