If they fail to do so then the local authority will carry out the work and take legal action to recover the costs, it is claimed.
The mayor of Bourgas, Dimitar Nikolov, said that the move is a necessary part of the resort's restoration and rejuvenation programme and will apply to properties in the central pedestrian streets particularly along Alexandrovska and Bogoridi.
The town hall will allow a reasonable time frame for the work to be carried out with the first phase beginning in Troikata Square.
Owners of properties that have cultural monument status will also be obliged to renovate their exteriors under the new decree and to do so they will have to obtain special documents first from the National Institute of Cultural Monuments.
The mayor has also accelerated the completion time for the refurbishment of Tsar Simeon St and the segment between Bulair and Cyril and Methodii. New pavements, tarmac, green belts, alleys and parking spaces are to be completed by the end of the month.
Nikolov is also taking a firm line on vandalism. Some parts of the city have been hit by damage in recent weeks.
