Earth-sheltered house permit in Austria: process and rules

The key points

In building law an earth-sheltered house is a dwelling. It needs the same building permit (or building notification) as any detached house; no building code has a separate category for earth-sheltered houses.
The first thing that matters is zoning: on building land an earth-sheltered house is possible, on green land as a rule it is not.
The technical requirements come from the OIB guidelines, which every province has adopted: daylight (at least 12% of the floor area), a view outside, escape route, protection against moisture and radon, energy performance certificate.
An earth-sheltered house with a glazed main façade and rooflights can meet these rules well; a fully buried house lit only by light wells usually cannot.

Which law applies: nine building codes

In Austria, building law is a provincial matter. There are nine building codes with their own procedures, plus the provincial spatial planning acts and the municipal zoning and development plans. The building authority of first instance is usually the mayor, in cities with their own charter the municipal administration, and in Vienna the building police (MA 37). The pattern is similar everywhere: a new dwelling needs a building permit, and some provinces allow a simplified procedure or a building notification under certain conditions.

Four examples

Lower Austria: new buildings and extensions require a permit under § 14 Z 1 NÖ BO 2014. Changing the ground level on building land also requires a permit (§ 14 Z 5), which matters for an earth-sheltered house with backfilling.
Upper Austria: in principle a building permit applies (§ 24 Oö. BauO 1994). Under § 24a, dwellings may also be built on the basis of a building notification if the neighbours sign the building plans and an authorised planner confirms compliance with all building law provisions. The authority can then prohibit the work within eight weeks (§ 25a).
Styria: small houses (residential use only, under 600 m² of usable floor area, no more than three storeys above ground) go through the simplified procedure under § 20 Z 1 and § 33 Stmk. BauG. The adjoining owners must sign the plans, otherwise the ordinary procedure applies. The authority decides within three months of receiving complete documents.
Vienna: alongside the ordinary procedure (§ 70 BO für Wien) there is the simplified procedure under § 70a, with confirmation by an independent chartered engineer. The authority can prohibit the work within three months. In protected areas such as the woodland and meadow belt the simplified procedure is not available.

How long the procedure takes and what it costs

Where provincial law does not set a shorter deadline, the authority must decide under the AVG no later than six months after a complete application. In practice the timeline depends above all on complete documents and on the neighbours. Costs include federal fees for the application and its annexes as well as municipal charges, for example the development levy in Lower Austria. What an earth-sheltered house itself costs is set out in our price guide.

Zoning first: building land or green land

Before you buy a plot, check the zoning. On green land, new dwellings are admissible in practice only in connection with agriculture and forestry, in Lower Austria for example under § 20 NÖ ROG 2014 for the housing needs of the farm owner within the farmstead. An earth-sheltered house is no exception: a planted earth cover does not turn a dwelling into an agricultural building. Rezoning is decided by the municipal council, and there is no entitlement to it.

Check before you buy:

Zoning plan: building land for residential use or building land for agricultural use? You can inspect it at the municipality or in the provincial GIS, in Vienna online at the City of Vienna.
Development plan: form of development, building height or building class, density, building lines, requirements on roof shape and changes to the terrain.
Building plot status and servicing (access, water, sewer or soakaway). Upper Austria has a separate building plot procedure for this.
Land register (easements, rights of way for utilities), hazard zone plan and slope water.
Radon map: is the municipality in a radon precaution or radon protection area?

A preliminary meeting with the municipality's building expert, with a site plan and a section sketch, is very helpful. It is the place to clarify how the municipality will measure building height and ground level for an earth-sheltered house.

What is examined particularly closely with an earth-sheltered house

The provinces have adopted the OIB guidelines (2023 edition) into their building technology regulations, in some cases with variations. The following points decide whether an earth-sheltered house is approved.

Daylight and view outside (OIB guideline 3)

The light-admitting area of every habitable room (living room, bedroom, workroom, kitchen-living room) must be at least 12% of the floor area. What is measured is the structural clear opening of windows, roof domes and clerestory bands (point 9.1.1).
Above a room depth of more than 5.00 m the figure rises by 1% for each metre started (point 9.1.4). Example: an 8 m deep living room of 40 m² needs 15%, that is 6.0 m² of glazed opening.
In front of the windows, a clear 45 degree angle of light incidence is required (point 9.1.2). A narrow light well rarely meets this.
The required windows need 2.00 m of clear view, and in at least one habitable room of every dwelling a window at a height of 1.20 m must give a view 6.00 m out into the open (point 9.2).

An earth-sheltered house achieves this with a glazed main façade facing the garden and with rooflights for the rear zones of the rooms. This makes it possible to light rooms 6 to 8 m deep.

Basement or living space?

Whether a room counts as a habitable room depends on its use and fittings, not on the earth above it. Under OIB Guideline 3, point 11.1, every residential storey must have at least one habitable room whose window side lies above the adjoining ground along its full length. The clear room height must be at least 2.40 m in buildings with no more than three dwellings; individual provinces set different figures. Ventilation is provided by windows to the open air or by mechanical ventilation.

Under the OIB definitions, a storey counts as below ground if no more than half of its outer boundary surfaces in total lie above the adjoining ground. This affects the building class, the number of storeys and, in part, the calculations in the development plan. Clarify this classification with the authority early on.

Escape routes and fire safety (OIB Guideline 2)

From any point in any room, a direct exit to the open air or a staircase must be reachable within a walking distance of no more than 40 m (point 5.1.1). In a single-storey earth-sheltered house with doors in the glazed facade this is easily met. A detached single-family house usually falls into building class 1, for which the requirements on smoke extraction from storeys below ground do not apply (point 3.12.1). Smoke alarms are mandatory in all habitable rooms except kitchens and in escape corridors.

Height, distances and ground levels

Building heights are measured from the ground: in Styria from the natural ground level, in Lower Austria from the reference level. The earth cover and backfill are changes to the ground level and must be shown in the submission drawings as ground before and after. Distances to neighbouring boundaries are governed by each province itself. Embankments and hillside water at the plot boundary affect the neighbours, so bring them into the conversation early.

Structure, waterproofing and radon

The earth load on the roof slab and the walls requires its own structural verification, prepared by a chartered civil engineer for building construction or a master builder.
Buildings with habitable rooms must be protected against moisture from the ground (OIB Guideline 3, point 6.1). For watertight concrete, the Austrian ÖBV guideline Wasserundurchlässige Betonbauwerke: Weiße Wannen applies.
In radon precaution and radon protection areas, radon ingress must be prevented. The reference value is 300 Bq/m³ as an annual mean (OIB Guideline 3, point 8.2.1). Precaution areas cover the whole of Carinthia, Salzburg and Tyrol and most of Lower Austria, Upper Austria, Styria and Burgenland. The measures are described in ÖNORM S 5280-2.

A continuous base slab of watertight concrete with sealed service penetrations is at the same time effective radon protection.

Energy performance certificate (OIB Guideline 6)

A new dwelling requires an energy performance certificate; in Lower Austria it is an attachment to the building application (§ 18 NÖ BO 2014). Components in contact with the ground are calculated separately in it. The earth cover evens out temperature swings, but it does not replace thermal insulation.

Who plans and signs

Submission drawings are prepared by authorised planners: master builders under the Trade Act or chartered engineers (architects, civil engineers for building construction). Upper Austria expressly requires a legally authorised person (§ 29 Oö. BauO 1994). In Lower Austria the authors are liable for completeness and accuracy (§ 18 para. 2). The works are directed by an authorised site manager, who certifies at the end that the building has been carried out in accordance with the drawings.

The usual submission documents are:

building application or building notification (the municipality's form) with a land register extract or the owners' consent
submission drawings: site plan, floor plans, sections, elevations, ground levels before and after
building description and energy performance certificate
depending on the province and municipality: evidence on structure, surface water, drainage and parking spaces, plus the neighbours' signatures (Upper Austria § 24a, Styria)

The process step by step

Check the zoning, the development plan, hazard zones and the radon map, ideally before you buy the plot.
Obtain a ground investigation report covering groundwater and hillside water.
Prepare a preliminary design and discuss it with the municipality's building expert.
Submission planning with an authorised planner, energy performance certificate, structural concept.
Submit the building application, simplified procedure or building notification, and inform the neighbours early.
Await the building hearing and the building permit, and note when it becomes legally binding (with a building notification: expiry of the objection period).
Notify the authority of the start of construction and of the site manager.
Construction: white tank, sealing of the joints, radon protection, earth cover and planting.
Notify completion (completion notification, in Upper Austria Baufertigstellungsanzeige) together with the certificates. A separate occupancy permit is generally no longer required in the provinces named.

How Talpa House works with you

Talpa House has designed and built earth-sheltered houses of watertight monolithic concrete (white tank principle) with a green roof since 2010. More than 21 houses stand in Slovakia, the Czech Republic and Hungary; in Austria we have not built yet. Here we are looking for local partners. The turnkey package includes the design and support through the permit procedure. The submission drawings are signed by a master builder or chartered engineer authorised in Austria with whom we work. Our houses receive daylight through glazed facades and rooflights.

Calculate your house in the configurator, read the price guide, arrange a visit or write to us. For Germany there is a separate guide to building permits.

Frequently asked questions

Do I need a building permit for an earth-sheltered house?

Yes. An earth-sheltered house is a new residential building and therefore requires a permit. Depending on the province, a simplified procedure (Styria, Vienna) or a building notification with neighbours' signatures (Upper Austria) is enough instead of the ordinary procedure.

May I build an earth-sheltered house on green land?

As a rule, no. Houses are only permitted on green-belt land in narrowly defined exceptions, usually for agricultural and forestry operations. The fact that the house is barely visible makes no difference.

Does an earth-sheltered house count as a basement?

Not if it is planned properly. Rooms with a 12% glazed area, a view out, a ceiling height of 2.40 m and a floor above ground level on the window side are fully fledged habitable rooms.

Are rooflights enough for daylight?

Dome rooflights count towards the glazed area. For the required view out, however, at least one habitable room needs a window with 6 m of clear view. That is why good designs combine a glazed facade with rooflights.

Is radon a problem in an earth-sheltered house?

In large parts of Austria, radon protection is mandatory for new builds, whether the house is earth-sheltered or not. A sealed floor slab and sealed service penetrations deal with it at shell stage. The radon map shows whether your municipality is affected.

How long does the building permit take?

That depends on the province, the procedure and whether your documents are complete. Statutory deadlines: eight weeks to prohibit a notified building project in Upper Austria, three months in the simplified procedure in Styria and Vienna, otherwise a maximum of six months under the AVG.

This guide is general information, not legal advice. The rules differ from province to province and from municipality to municipality; what your building authority tells you is what counts.

Earth-sheltered house in Austria: building permit, zoning and building code explained