The invention relates to a holding apparatus (10) for a housing (11) and method for affixing the holding apparatus (10) and the housing (11) to an affixation surface, in particular an external building surface. The holding apparatus (10) has two holding parts (12) that each have a holding segment (25) that extends in a longitudinal direction (L). At least one of the two holding parts (12) additionally has a locking segment (43). Two attachment parts (46) and, for each locking segment (43), one locking part (47) are affixed to a rear wall (11b) of the housing (11). To mount the housing (11) on the holding apparatus (10), the two attachment parts (46) are firstly each brought into engagement with their respective holding segment (25). By displacing the housing (11) in the longitudinal direction (L), the locking part (47) enters into engagement with the locking segment (43). A continued movement of the housing (11) in the longitudinal direction (L) is at least delimited.