Federal Act
on Spatial Planning
(Spatial Planning Act, SPA)¹

¹ Build­ings and in­stall­a­tions out­side build­ing zones that may be used in ac­cord­ance with the law but which no longer con­form to zone re­quire­ments are in prin­ciple pro­tec­ted in their cur­rent state.

² Such build­ings and in­stall­a­tions may, with the per­mis­sion of the com­pet­ent au­thor­ity, be ren­ov­ated, par­tially mod­i­fied, mod­er­ately ex­pan­ded or re­con­struc­ted, provided they have been law­fully con­struc­ted or mod­i­fied.⁵⁹

³ The fore­go­ing also ap­plies to farm­houses and at­tached com­mer­cial build­ings that have been law­fully con­struc­ted or mod­i­fied be­fore the par­cel of land con­cerned be­come part of the area where build­ing is not per­mit­ted in ac­cord­ance with fed­er­al law. The Fed­er­al Coun­cil shall is­sue reg­u­la­tions in or­der to pre­vent neg­at­ive con­sequences for ag­ri­cul­ture.⁶⁰

⁴ Changes to ex­tern­al ap­pear­ance must be ne­ces­sary to en­able mod­ern res­id­en­tial use or to up­grade en­ergy ef­fi­ciency or so as to blend more har­mo­ni­ously in­to the land­scape.⁶¹

⁵ Every case is sub­ject to com­pat­ib­il­ity with the pri­or­ity con­cerns of spa­tial plan­ning.⁶²