Glossary
Sondereigentum
Individual Condo Property. The part of a condominium you own outright — the flat's interior spaces and non-structural components. Everything structural or shared is Gemeinschaftseigentum.
The boundary decides who pays: interior surfaces, non-bearing walls, sanitary fittings and interior doors are yours; the building shell, roof, windows (usually), pipes to the branch point and balcon structures are common property funded by all owners.
The Teilungserklärung can shift some cost burdens (e.g. window replacement) to individual owners — read it, because 'the WEG will pay' is not always true.