Building lines in Switzerland: The invisible boundary to the road
- Simon Käslin
- 23 hours ago
- 16 min read
Updated: 5 hours ago
A building line is a line laid down by the authorities that limits the buildable area of a plot. It secures space for roads, service lines, watercourses and future extensions. All eight cantons in the Zurich region, eastern Switzerland and central Switzerland use this instrument, and in every one of them the building line takes precedence over the ordinary distance from the road. What differs is the legal source, the number of metres that applies without a line, the point from which it is measured and whether the line is a minimum setback or an obligation to build. The boundary setbacks towards the neighbours remain untouched in every case.
This article compares building lines in Switzerland across eight cantons, namely Zurich, St Gallen, Thurgau, Schwyz, Zug, Aargau, Schaffhausen and Lucerne: legal basis, effect, distance from the road without a line, exemptions, acquired rights and compensation. Plus the federal building lines along national roads and railway installations.
Table of contents
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1. What a building line is and what it secures
The building line is a restriction on ownership set out in a plan. It does not say how high or how large you may build, but where the buildable area ends. Between the line and the road the ground normally stays free so that a later road widening, a pavement, a cycle path or a service line has room without a house having to be demolished first.
The Zurich statute sums up the purpose, and it applies in the same sense in all the cantons covered here:
§ 96 para. 1 PBG (LS 700.1): Building lines limit development and serve in particular to secure existing and planned installations and areas as well as the design of the built environment.
For the client this means: a building line is not a recommendation and not a guide value, it is a restriction on ownership recorded in the land use plan and in the cadastre of public-law restrictions on landownership. It takes effect directly on every building application, regardless of what the building and zoning regulations would otherwise allow. And it often takes effect earlier than people expect: in the canton of Zug, new buildings within the building line area are already inadmissible from the moment the plan is put on public display (§ 34 para. 1 PBG), long before the plan becomes legally binding.
Besides the traffic building line, several cantons have further types of line for operating installations, supply lines, watercourses, forest and protected objects. Zurich and Schaffhausen also have the level line, which does not fix the position in plan but the height.
2. Where building lines in Switzerland are regulated by canton
The biggest practical difference between the cantons is not the word but where the rule is located. Zurich, St Gallen, Thurgau, Schaffhausen and Lucerne regulate the building line in their planning or building act. Schwyz, Zug and Aargau split it between planning law and road legislation.
Canton | Designation | Legal source | Authority that sets it |
Zurich | Building line, plus level line | §§ 96 to 110 PBG, LS 700.1 | Municipality for municipal installations, otherwise the competent cantonal directorate (§ 108 PBG) |
St Gallen | Building line, building line plan | Art. 29 to 31 PBG, sGS 731.1; Art. 102bis, 104, 107 StrG, sGS 732.1 | Canton for cantonal roads, otherwise the municipality |
Thurgau | Building line, building line plan | § 25 PBG, RB 700; §§ 44 to 47 StrWG, RB 725.1 | Municipal authority (§ 25 para. 2 PBG) |
Schwyz | Building line in the land use plan | §§ 23, 33, 68 PBG, SRSZ 400.100; §§ 40 to 42 StrG, SRSZ 442.110 | Municipal council in the land use planning procedure, subject to approval by the cantonal government |
Zug | Building line and building area | §§ 31, 34, 55 PBG, BGS 721.11; § 17 GSW, BGS 751.14 | Whoever is responsible for the traffic installation (§ 31 para. 2 PBG) |
Aargau | Building line in the servicing plan | §§ 17, 93, 111 BauG, SAR 713.100 | Municipality in the servicing plan, canton for cantonal roads |
Schaffhausen | Building line and level line | Art. 12 to 16 and Art. 30 BauG, SHR 700.100 | Municipal council, binding only once approved by the cantonal building department |
Lucerne | Building line and building area | §§ 30, 31 PBG, SRL 735; §§ 64, 84, 85 StrG, SRL 755 | Municipal land use plan or procedure under the roads act |
3. The building line takes precedence over the distance from the road
On this point all eight cantons agree, and some of them say so word for word:
Thurgau, § 25 para. 3 PBG: Building lines take the place of the general setback rules.
Lucerne, § 30 PBG: Building lines and building areas take precedence over all other setback rules under public law.
Schwyz, § 68 para. 2 PBG: Where building lines exist, they take precedence over the setback rules.
Aargau, § 17 BauG: Building lines mark the minimum distance from servicing installations, watercourses, forests and protection zones and take the place of the general setback rules.
Zurich, Zug and Schaffhausen put it the other way round: the statutory distance from the road applies only where no building lines exist (§ 265 PBG, § 17 GSW, Art. 30 BauG).
The practical consequence is the same everywhere. The strip between the building line and the road is lost for the building volume. That affects not only the house itself but also elements people rarely think of, namely bay windows, canopies, covered seating areas, external stairs and ramps. What is exceptionally still permitted is set out in chapter 8.
4. Minimum line or mandatory line: the difference that derails projects
This is the point at which experience from one canton turns into a mistake in the next. A building line is not necessarily a boundary you have to stay behind. It can also be a line you have to build on.
St Gallen says so expressly: building lines fix the minimum distance or the mandatory distance (Art. 29 PBG).
Zurich has special purposes for traffic building lines such as contiguous development and the design of traffic spaces and squares (§ 97 PBG). Here too the line can become an obligation to build.
Thurgau also has mandatory and design building lines alongside the setback building line.
Anyone who brings along the everyday formula "building line means no closer" may design past a line they were in fact required to build on. What counts is never the word but the building line plan with its legend and the associated regulations.
5. Without a building line: distances from the road compared across cantons
If there is no building line, the statutory distance from the road applies. It varies from canton to canton, and not only in the number of metres but also in the system: most cantons grade it by road owner, Schwyz by functional class and Schaffhausen by type of development and location.
Canton | Distance from the road without a building line | Measured from | Legal source |
Zurich | 6 m towards roads and squares, 3.5 m towards paths | Road and path boundary | § 265 para. 1 PBG |
St Gallen | 4 m on cantonal roads, 3 m on municipal roads | Road boundary | Art. 104 and 107 StrG |
Thurgau | 4 m towards cantonal roads and paths, 3 m towards municipal roads and paths | Plot boundary | § 44 para. 1 StrWG |
Schwyz | 6 m main road, 4 m connecting road, 3 m secondary road, 3 m private road | by road class, not by owner | § 41 StrG, § 65 para. 2 PBG |
Zug | 6 m on cantonal roads, 4 m on municipal roads | Edge of the road or the pavement | § 17 GSW |
Aargau | 6 m towards cantonal roads, 4 m towards municipal roads | Road boundary marker | § 111 BauG |
Schaffhausen | 5 m open development, 2.5 m cycle and foot paths, 15 m cantonal road outside built-up areas | public land | Art. 30 para. 1 BauG |
Lucerne | 6 m cantonal roads, 5 m municipal roads, 4 m agricultural and private roads, 2 m paths | by road category | § 84 StrG |
Two observations for practice. First: only Zurich, Thurgau and Lucerne regulate the distance towards paths expressly with a figure of their own. Anyone assuming in another canton that a footpath is automatically privileged should check the municipal rules. Second: in Schwyz the answer "that is a municipal road" gets you nowhere. If it is classified as a main road, 6 metres apply instead of 3.
6. Where the measurement starts: the most expensive mix-up
Two cantons with the same number of metres can produce completely different building envelopes because they measure from different points.
From the plot boundary of the road: Zurich (§ 265 PBG), St Gallen (Art. 107 StrG), Thurgau (§ 44 StrWG).
From the road boundary marker: Aargau (§ 111 BauG), at right angles to the line of the road.
From the edge of the road or the pavement: Zug (§ 17 para. 2 GSW).
From public land: Schaffhausen (Art. 30 BauG).
The difference is not a fine point. Where a road plot is considerably wider than the carriageway and the pavement together, the plot boundary and the edge of the pavement lie several metres apart. The same nominal distance of 4 metres then produces building envelopes in Zug and in Thurgau that differ by metres. So with every preliminary measurement, check whether the land register or the road surface forms the reference point.
7. Building line and boundary setback are two different things
The distance from the road protects public space, the boundary setback protects the neighbours. The building line replaces the first, not the second. A project that complies with the building line can still fail on the boundary setback.
One special case links the two. Under § 270 para. 2 PBG, in the canton of Zurich a boundary setback of 3.5 metres applies laterally within 20 metres of the traffic building line or of the building limit line replacing it, irrespective of the position and depth of the plots involved. Within this strip along the road a separate, uniform boundary setback therefore applies. How boundary setbacks and distances from the road together affect the usable volume is shown in the article on the utilisation ratio, floor space ratio and building mass ratio.
8. What is still permitted inside the building line
No canton simply prohibits everything in the building line area. The exemptions are the real lever, and they differ considerably.
Underground, Zurich: The building line plan can limit the effect of the line to certain vertical zones (§ 99 para. 2 PBG). Where it does so, the subsurface is free. That is not shown on the GIS map, only in the plan.
Underground, Lucerne: Different building lines can be set for structures above and below ground level (§ 30 para. 3 PBG). Without a diverging rule, 3 m apply underground towards roads and 2 m towards paths (§ 84 para. 4 StrG).
Underground, Thurgau: With the permission of the municipal authority the distance can be reduced to as little as 50 centimetres (§ 44 para. 2 StrWG).
Projecting parts of buildings, Zug: at most 1.50 m into the building line area or beyond the building area (§ 27 of the ordinance to the PBG).
Projecting parts of buildings, Schaffhausen: without a pavement at least 4.50 m above the level line, with a pavement at least 2.50 m, and at most 1.50 m beyond the building line (Art. 16 BauG).
Projecting parts of buildings, Zurich: permitted, but to be removed without compensation as soon as the execution of the works requires it (§ 100 para. 2 PBG).
Small structures, Thurgau: may be placed right up to the road and path boundary with a permit, provided visibility for traffic does not suffer (§ 45 StrWG). Garages with the entrance facing the road need 5 m, and 8 m for larger vehicles (§ 46 StrWG).
More extensive use, Zurich: The building permit can allow more extensive use of the building line area, if necessary subject to safeguarding conditions (§ 100 para. 4 PBG).
One pattern runs through several cantons: the waiver undertaking. In Zug, conversions and additional storeys within the building line area are permitted provided the public authority does not have to compensate the added value created when it later takes up the land (§ 34 para. 2 PBG); small structures as well as parking and servicing installations are exempt from the building ban but as a rule not from this undertaking (§ 34 para. 3 PBG). In St Gallen, Art. 102bis StrG uses the same construction for annexes and ancillary buildings. Anyone who obtains such an exemption obtains it subject to a reservation and not permanently.
9. Existing buildings: acquired rights compared across cantons
An existing house that projects beyond the building line does not have to be demolished. How far you may work on it, however, varies considerably from canton to canton, and that decides the value of a property you buy with the intention of converting it.
Zurich: Buildings that contravene the building line may be maintained and modernised in line with their previous use (§ 101 PBG). Extending them, no.
St Gallen: Maintenance and renewal to current standards are permitted (Art. 31 PBG), supplemented by the general protection of existing structures in Art. 109 PBG.
Thurgau: Renewal and even extension are possible, provided the conflict with the rule is not substantially increased (§ 94 PBG). That is the most generous regime in this comparison.
Schwyz: Existing buildings may be maintained and renewed to current standards; extensions require a permit (§ 72 PBG, § 45 StrG).
Lucerne: On buildings that project beyond the statutory distances from the road, no structural alterations may in principle be carried out (§ 85 StrG, subject to § 88 StrG). That is the strictest regime in this comparison.
For a replacement building the same applies in every canton: the acquired rights end with the building. Anyone buying with the intention of demolishing has to reckon with the set-back building envelope, not with today's volume. Exactly this difference belongs in every property analysis before purchase.
10. Compensation, the right to compel purchase and the duty to take over
The principle is the same everywhere: a building line is not compensated merely because it costs building volume. Compensation only arises once the restriction is equivalent in its effect to an expropriation. What differs is whether the canton also provides a right to force the plot onto the public authority.
Canton | Compensation | Right to compel purchase or take-over |
Zurich | Only in the case of material expropriation (§ 102 PBG) | Right to compel purchase where the plot becomes unbuildable, time limit ten years (§§ 103, 104 PBG) |
Zug | Material expropriation under § 66 PBG | Right to compel purchase five years after the plan becomes legally binding (§ 55 para. 1 lit. b PBG) |
Lucerne | Under general expropriation law | Take-over of the entire plot where development is made impossible (§ 76 StrG) |
Schwyz | Full compensation where the effect is equivalent to expropriation (§ 35 PBG) | Duty to take over on partial cession where the remainder becomes unusable (§ 34 PBG) |
Schaffhausen | Only where the effect is equivalent to expropriation (Art. 75 para. 1 BauG) | No separate rule on the right to compel purchase found |
St Gallen, Thurgau, Aargau | Under general cantonal expropriation law | No special rule specific to building lines found |
For Zurich and Zug the time limit is the decisive point. Anyone who only notices after ten or five years respectively that their plot can no longer be built on because of a building line loses the right. With a plot cut deeply by a line it is therefore worth checking early, not only when the building project starts.
11. Federal building lines: national roads and railways
Alongside the cantonal building lines in Switzerland there are two sets under federal law that are kept as separate topics in the cadastre of public-law restrictions on landownership and that nobody expects on a plot far away from any motorway.
National roads (NSG, SR 725.11). Building lines must be fixed on both sides of the planned road in the detailed projects (Art. 22). Between these lines, neither new buildings may be erected nor conversions carried out without a permit; mere maintenance does not count as a conversion (Art. 23). Exemptions are possible where no public interests are harmed, with the federal office being consulted beforehand (Art. 24). Compensation is paid only for what amounts to an expropriation, and claims must be registered within five years (Art. 25). Upstream of this, Art. 14 NSG provides for the planning zone, which keeps the road space free before a detailed project even exists.
Railways (EBG, SR 742.101). The Federal Office of Transport can fix building lines to secure existing or future railway installations (Art. 18q). Between the building lines, and between the building line and the railway installation, structural alterations that conflict with that purpose are inadmissible (Art. 18r). Compensation is available where the effect is equivalent to expropriation, with a ten-year period for registering claims (Art. 18u). Important for housing close to the railway: so-called ancillary installations are subject to cantonal law, but the cantonal building permit requires the consent of the railway company where the plot occupies or adjoins railway land (Art. 18m). There is no figure in metres fixed by federal law for the building distance from the railway.
12. How to find the building lines on your plot
Call up the cadastre of public-law restrictions. The extract for your plot shows the federal and cantonal topics that restrict ownership, among them the building lines of the national roads and of the railway installations. Depending on the canton, municipal building lines appear under land use planning or as a separate topic.
Check the cantonal geoportal. There you see the course of the line in the context of the zoning plan. The map is an orientation aid, not a legal title.
Ask the municipality for the building line plan. The plan tells you what the map does not show: the legend, whether it is a minimum line or a mandatory line and whether the effect is limited to certain vertical zones. That is the point at which it is decided whether you may build underground.
Clarify whether a road project is under way. A line from an ongoing detailed project or plan approval procedure can already take effect from the moment it is put on display, expressly so in Zug (§ 34 para. 1 PBG).
Determine the measuring point. Plot boundary, road boundary marker or edge of the pavement. Without this step every preliminary measurement is useless.
If the check shows a tight building envelope, a full assessment before the purchase is worthwhile. How such an analysis is structured is shown in the article on buying land in Switzerland. For the volume assessment that follows, the article on the feasibility and volume study is the next step.
13. Worked example: what a building line costs in building land
Starting point: a rectangular plot of 30 by 22 metres, that is 660 square metres, on a municipal road. We compare the same plot in three constellations. The boundary setback is 4 metres to the other three sides in all three cases.
Constellation | Distance from the road | Building envelope | Area of the building envelope |
Without a building line, canton of St Gallen | 3 m | 23 m by 15 m | 345 m2 |
Without a building line, canton of Zurich | 6 m | 20 m by 15 m | 300 m2 |
Building line 12 m from the road boundary | 12 m | 14 m by 15 m | 210 m2 |
Between the constellation without a building line in the canton of St Gallen and the building line at 12 metres there are 135 square metres of building envelope. With two full storeys that corresponds to around 270 square metres of floor space, which depending on the region means a seven-figure difference in sale value. And that with an identical plot size and an identical utilisation ratio.
The order matters: what counts first is whether the utilisation ratio can be exhausted at all. With tight building envelopes it is often not the ratio that limits the project but the geometry. A plot with a utilisation ratio of 0.5 is of little use if the remaining building envelope can no longer accommodate the permitted area.
14. Five mistakes that get expensive with building lines
Taking the number of metres from the neighbouring canton. Between 2.5 metres in Schaffhausen along a footpath and 6 metres in Zurich, Zug, Aargau or Lucerne along a cantonal road lies a whole building envelope.
Not checking the measuring point. From the boundary, from the road boundary marker or from the edge of the pavement produces completely different results for the same number of metres.
Taking the line for a minimum setback although it is an obligation to build. In St Gallen both are set out expressly in the same article.
Forgetting the underground options. Where little is possible above ground, the lever shifts below ground level. Zurich, Lucerne and Thurgau expressly leave room there.
Confusing acquired rights with a replacement building. The acquired rights end with the building. Anyone valuing a property with the intention of demolishing has to calculate with the set-back building envelope.
How these points play out in the building application and what evidence the authority requires is covered in the article on building applications and building permits. For plots at the edge of the forest, the forest setback also comes into play, and it follows a logic of its own.
15. Frequently asked questions about building lines
What is a building line, explained simply? A line laid down in a plan that limits the buildable area of a plot. Under § 96 para. 1 PBG of the canton of Zurich it serves to secure existing and planned installations and areas as well as the design of the built environment; the other cantons word it in the same sense. As a rule nothing may be built between the building line and the road, and the strip stays free for a later widening.
Does the building line replace the distance from the road? Yes, and it does so in all the cantons compared here. Thurgau, Lucerne, Schwyz and Aargau state expressly that the building line takes precedence over the general setback rules. Zurich, Zug and Schaffhausen put it the other way round: the statutory distance from the road applies only where there is no building line. The boundary setbacks to the neighbouring plots remain in place in every case.
How large is the distance from the road without a building line? It varies from canton to canton. Zurich requires 6 metres towards roads and 3.5 metres towards paths, St Gallen 4 and 3 metres depending on the road owner, Thurgau likewise 4 and 3 metres, Zug and Aargau 6 metres on cantonal and 4 metres on municipal roads, Lucerne 6, 5, 4 and 2 metres depending on the category. Schwyz grades by road class with 6, 4 and 3 metres, Schaffhausen by type of development with 5 metres for open development.
May I build underneath a building line? Often yes, but it depends on the canton and on the plan. In the canton of Zurich the building line plan can limit the effect to certain vertical zones and release the subsurface (§ 99 para. 2 PBG). Lucerne expressly allows different building lines for above and below ground level (§ 30 para. 3 PBG). In Thurgau the distance can be reduced to as little as 50 centimetres with a permit (§ 44 para. 2 StrWG).
What happens to my house that projects beyond the building line? It enjoys acquired rights, but to differing extents. Zurich allows maintenance and modernisation in line with the previous use (§ 101 PBG), Thurgau even extensions provided the conflict is not substantially increased (§ 94 PBG), whereas Lucerne in principle allows no structural alterations at all (§ 85 StrG). For a replacement building the acquired rights end with the building everywhere.
Do I get compensation for a building line? Only if the restriction is equivalent to an expropriation. A mere loss of building volume is not enough. Zurich additionally provides a right to compel purchase where the plot becomes unbuildable, to be asserted within ten years (§§ 103, 104 PBG). Zug provides a right to compel purchase after five years (§ 55 PBG), Lucerne a duty to take over (§ 76 StrG) and Schwyz a duty to take over on partial cession (§ 34 PBG).
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