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Building class finder

About this app

Change height, use units and detachment on a 3D building: the class under § 2(4) of the Baden-Württemberg code jumps, and the effects on construction, stairwell and procedure appear with section.

With explain mode: an AI tutor walks you through the app, points out what matters in the scene and answers your questions.

What the building class follows from

The building code of Baden-Württemberg sorts buildings into five classes in § 2(4). Three quantities decide: the height, the number and area of the use units, and whether the building is detached. The height is the level of the finished floor of the highest storey in which a habitable room is possible, above the mean ground level. Ridge and eaves play no part. Areas are gross floor areas, basements are disregarded. The limits lie at 7 m, 13 m, two units and 400 m².

What the app shows

You see a building on sloping ground: storeys as individual slabs, use units in their own colours, and at the side a height gauge with marks at 7, 13 and 22 m. It runs from the mean ground level of the four building corners to the floor of the top storey with a possible habitable room and flips when it crosses a mark. A large step shows the class from 1 to 5, and the Effects panel names with section what follows: fire resistance of load-bearing walls and floors, stairwell, stairs, corridors and whether the notification procedure is possible.

What you can try

Drag the roof to add storeys, drag the corner to change the footprint, and tap a storey to split it into units. Choose a flat roof, a pitched roof with a loft without habitable room, or an attic storey, attach a neighbour, change the use and the slope. Five examples from a detached house to a high-rise load finished designs. You see how one more storey or flat shifts the class and with it the construction, for example timber, stairwell and fire resistance.

Frequently asked questions

How is the height for the building class measured?
Under § 2(4) sentence 2 of the Baden-Württemberg code the height is the level of the finished floor of the highest storey in which a habitable room is possible, above the mean ground level. So the floor of that storey decides. A loft in which no habitable room is possible is not a storey and is left out. A converted attic storey, by contrast, raises the height by one storey.
What distinguishes building class 1 from class 2?
Both classes require a height of up to 7 m and at most two use units totalling at most 400 m². Class 1 applies to detached buildings, class 2 to buildings directly attached to a neighbouring building. Detached buildings used for agriculture or forestry belong to class 1 regardless of these limits.
When is a building a high-rise in Baden-Württemberg?
Under § 38(2) no. 1 of the code, high-rises are buildings with a height under § 2(4) sentence 2 of more than 22 m. They are special buildings, on which particular requirements can be imposed. The notification procedure is excluded for special buildings under § 51(1), even for residential buildings.
What can I try in the building class finder?
You change storeys, footprint, use units, roof, neighbour, use, basement and slope directly on the 3D model and immediately see height, class and effects with section. The app shows the version of the code of 5 March 2010, last amended 18 March 2025. It is not legal advice, the current statutory text is decisive.

Subject: Architecture & scenography

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