What is the escape level?
The escape level decides the building class, and the building class decides fire safety. Three words in the definition make the difference: highest, above-ground, after completion. Piloti derives the building class from it and asks for the value when the project lacks it.
Definition from the OIB-Richtlinien, Begriffsbestimmungen, May 2023 edition, in our own translation.
In short
Under the OIB definitions, the escape level (Fluchtniveau) is the height difference between the top of the floor of the highest above-ground storey and the ground surface adjoining the building after completion, on average. From it and the other values Piloti derives the building class.
Escape level (Fluchtniveau)
“Height difference between the top of the floor of the highest above-ground storey and the ground surface adjoining the building after completion, on average.”
How Piloti helps
Piloti derives the building class from the escape level and the other values, citing the definitions and the OIB edition that applies in the state. If the escape level is missing, it asks for it instead of estimating.
What the definition says exactly
It is measured to the top of the floor, not to the eaves or the ridge. So the escape level is not a building height; it is the height from which people on the top storey must escape and up to which the fire brigade must reach.
At the top, the highest above-ground storey counts. A separate definition says what an above-ground storey is: an unconverted roof space or a plant storey without dwellings or business units does not count. At the bottom, the adjoining ground after completion counts, not the original terrain and not the street.
“On average” evens out uneven ground around the building. How the average is formed in a specific case, on a steep slope or at a ramp to an underground garage, is a matter of interpretation. Record your assumption in the file.
The thresholds for the building class
- 7.00 m: together with no more than three above-ground storeys, building classes 1 to 3 reach up to here.
- 11 m: the limit of building class 4, with no more than four above-ground storeys.
- 22 m: the limit of building class 5. Above it a building falls into none of the five classes, and separate requirements apply.
- For a row house, the escape level is considered separately for each dwelling or business unit.
Where it tips in practice
A roof space is converted and becomes an above-ground storey: the escape level moves up a storey, and the building class may move with it. In existing buildings this is the most common surprise.
The ground is lowered or raised during landscaping: what counts is the state after completion, that is, what the submission drawings show as future ground. Anyone who calculates with existing levels calculates with the wrong value.
Good to know
How the average is formed in a specific case is for the design team to decide; Piloti shows what the definition says and states the assumption. It takes the escape level from your documents instead of recalculating it from spot heights in the drawing.
Questions
How is the escape level calculated?
Take the top of the floor of the highest above-ground storey and subtract the level of the adjoining ground surface after completion, averaged around the building. How to form the average on strongly varying ground has to be interpreted case by case and recorded in the file.
Is the escape level the same as the building height?
No. The escape level ends at the top of the floor of the highest above-ground storey and comes from the OIB guidelines. Building height, eaves height or Bauklasse are governed by the state’s building code and the development plan, with their own measuring rules.
Does a roof storey count for the escape level?
Only if it is an above-ground storey, that is, if it contains dwellings, business units or parts of them. By definition an unconverted roof space does not count; a converted roof storey with living rooms does.
How is the escape level determined for a row house?
Under the row house definition, each dwelling or business unit is considered separately with regard to the escape level when classifying the building. On a slope, the houses in one row can end up with different values.