The Rating & Valuation Department will launch a citywide campaign tomorrow in which 100,000 letters, leaflets and posters will be distributed to owners and tenants of ground floor shops, owners' corporations and mutual aid committees, to ensure proper display of building numbers.

Correct display of building numbers enables efficient postal and emergency services.

The department advises numbers be located above or at either side of an entrance, with a minimum height of 50mm and 40mm in width. The colour of number should contrast clearly with its background. Damaged numbers should be repaired.

Building owners failing to comply with the law to display building numbers are liable to six months' jail and a $2,000 fine.