Can you help me?
... You need to clarify (building authority, architect, ?) / know which building law and above all primarily whether a
specific development plan exists for your area – and what stipulations it contains there.
I am not familiar with Austria, but for
Salzburg there is a general
"Development Basis Act" (BGG) (Note. however, the specific development plan for Eugendorf takes precedence, check the website of your municipality...):
The "building setback line" is generally defined in your regional planning law - Regional Planning Act, there § 55.
In the BGG for Salzburg § 25 states for example about distances:
(2) Provided that no provisions regarding the location of buildings on the building plot are specified by the development bases determined in the [B]development plan and provided that no other legal regulations prescribe a greater distance of buildings from the boundaries of the building plot or between buildings, the following provisions apply regarding the location of buildings on the building plot.
(3) For the distance of buildings from the property boundary opposite the traffic area, the building setback line or the building line applies. Otherwise, buildings on the building plot must be located so that their facades have a minimum distance from the boundaries of the building plot of three quarters of their height up to the highest cornice or the highest eaves, but in any case at least 4 m. If the building plot borders areas that are unbuildable due to their soil condition (bodies of water, embankments, etc.), this distance is reduced by half the width of these areas, but not below 4 m. The height up to the highest cornice or the highest eaves is to be calculated at each facade from the natural ground level. Eaves of only minor length that have no negative impact on the otherwise given sunshine and lighting conditions (eaves of half-hipped or shed-style hipped roofs) are not considered as the highest eaves here.
(4) On the building plot, each building must have a distance from another of at least the sum of their respective boundary distances prescribed in paragraph 3. The groups of buildings listed in § 58 lit a Regional Planning Act 2009 as well as attached buildings (§ 58 lit b Regional Planning Act 2009) are considered one building. This minimum distance provision does not apply to single-storey ancillary facilities that belong to residential buildings and serve the needs of the residents.
(..)
7a) Single-storey ancillary facilities belonging to residential buildings and serving the needs of residents may also be built on the building plot within the lateral minimum distance or in front of the building setback line, if the following conditions are met:
1.
The location of the ancillary facilities (for bicycles, waste containers and recycling bins as well as garages or covered motor vehicle parking spaces) must not contradict a provision according to § 53 para 2 no 12 or 16 Regional Planning Act 2009.
2.
The distance between the outermost parts of the building and the building plot boundary must be at least 2 m, unless the neighbors explicitly agree to a reduction of this distance and no greater distance is prescribed by other legal regulations.
3.
The side length of the ancillary facility (including roof overhangs) on the side facing the neighboring property must not exceed 4 m, but for garages or covered motor vehicle parking spaces it must not exceed 7 m. In such garages or covered motor vehicle parking spaces, subject to building technical requirements, rooms serving other purposes of such ancillary facilities may also be accommodated to a subordinate extent.
4.
The eaves height must not exceed 2.5 m, the ridge height must not exceed 4 m. If the ridge is located less than 3.5 m from the building plot boundary, its height must not exceed the imaginary line between the maximum permissible eaves height at the building plot boundary and the maximum permissible ridge height at a 3.5 m distance. These limitations do not apply if the neighbor explicitly agrees to the exceedance. And:
5.
This provision must not have already been used for the same building plot on the relevant side facing the neighboring property. This also applies if one or more buildings including ancillary facilities on this side already stand within the lateral minimum distance or can still be constructed based on an exception already granted according to para 8.
(...)
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Again: The above is only an example for Salzburg.
Check your development plan!
And it gets complicated with the 4 m building setback line in the north.
Because § 55 I Regional Planning Act for Salzburg (Regional Planning Act) states as a principle:
Building setback lines, building lines; building boundary lines; siting obligations
§ 55
(1) The
building setback line is the line that may not be exceeded by above-ground buildings towards the traffic area.
(..)
Exception may apply in the development plan for Eugendorf – e.g. as regulated in § 25 number 7a) BGG Salzburg, see above...