- A building may consist of two or more self-contained internal flats, offices, retail/commercial units or similar. Each internal unit should be separately numbered using unique sequential numbering separate to the main entrance to the numbered building.
- In all cases the courier or postal delivery method (door to door, communal post box, pigeonholes / drop boxes with external or internal access) should be determined before the internal numbering sequence is agreed. This may aid the numbering sequence and signage.
- An extension to the street numbering sequence should not be used for the internal numbering sequence of a building.
- The street numbering sequence should only be used to identify separate external entrances to the building.
- The building should be allocated a street number, for example,12 High Street. Internal sub- divisions should be allocated sub-division numbers, for example, Flat 1, 12 High Street.
- Where a building is subdivided and some units have an independent main entrance, these should be allocated suffixes, for example, 12 Park Road is split into two flats, the front door leading to stairs to the top floor flat and the rear door leading to the ground floor flat. These should be numbered 12 (front door) and 12A (rear door) Park Road.
- Letter Suffixes should not be used for the numbering sequence of internal sub-divisions. For example, Flat 2, 13 Smith Street, not Flat A, 13 Smith Street and not 13A Smith Street which may already be used by an adjoining infill building or rear/separate entrance to the building.
- Punctuation marks should not be used, for example Flat 1.01 or Flat 11/01. As these cause confusion for identification and data search purposes.
- Abbreviations or punctuation should be avoided for floor/level names. If necessary use “First Floor” rather than “1st Floor”,” for example.
- A suitable prefix to the number to aid the identification of the type of unit should be applied, see building prefixes.
- Units may be addressed with the prefix of, for example Flat or Apartment but should be consistent in their use throughout the building and/or development. The use of the prefix Studio and/or Penthouse should be avoided as this may cause confusion.
- The sequence numbering of each individual unit should follow the natural circulation of the building. The lowest number 1 should appear on the left-hand side nearest to the main entrance to the building and continue clockwise for that floor. On subsequent floors above the ground floor, numbering should continue adjacent to the main stair core or lifts. The direction of circulation of the numbering should be maintained going upwards throughout the building floors above the ground floor or alternatively start at number 1 on each floor.
- Where floors are below the main entrance the use of level numbers instead of floor numbers will probably be more appropriate. The numbering sequence of each individual unit should follow the natural circulation of the building from the lowest level or alternatively start at number 1 on each floor or level. For example, a twelve-storey building may contain three floors below the main entrance floor. This means the building has fifteen levels. The lowest floor below the main entrance floor would be level one. Number 1 should appear on the left- hand side adjacent to the main stair core or lifts of level one and continue clockwise for that floor. On consecutive floors or levels, numbering should start at number 1 adjacent to the main stair core or lifts. The clockwise direction of circulation of the numbering should be maintained on all levels.
- In residential/commercial/industrial buildings with multiple floors or levels, for example, blocks of flats/apartments/commercial units etc there are four numbering methods. In each example below it is assumed that there 20 apartments on 12 floors:
Example of flat numbering Sequential numbering for the whole building. Ground floor: 1 to 20
First floor: 21 to 40
Second floor: 41 to 60
Eleventh floor: 221 to 240Sequential numbering per floor. Ground floor: 1 to 20
First floor: 1 to 20
Second floor: 1 to 20
Eleventh floor: 1 to 20Sequential numbering per level.
Level one: 1 to 20
Level two: 1 to 20
Level three: 1 to 20
Level twelve: 1 to 20Sequential numbering per floor in a similar manner to hotel rooms, for example, all units on the first floor will commence with the number 1, followed by the unit number e.g., apartment seven on the first floor will be numbered 107. Ground floor: 1 to 20
First floor: 101 to 120
Second floor: 201 to 220
Eleventh floor: 1101 to 1120 - In each of the above methods the building should be numbered to the street nearest the entrance used for numbering the building. Conversion works may introduce subsequent floors or levels below ground level. This scenario would suit option 2 and 3 but for option 1 and 4 would require the use of the floor name or a re-number of the building.
- Where the building contains a single continuous corridor or corridors on a floor. The units should be numbered to the left to the end of the corridor and then on the right returning from the end of each corridor to maintain the clockwise sequence of numbering.
- Where there are multiple internal corridors, numbering should begin from the main entrance or the main stair or lift core and proceed clockwise around the corridors.
- Where a building has multiple entrances, with each entrance having separate units or corridors of units then each entrance should be numbered separately as the main entrance to that part of the building or separate block of the building, and the units accessed via this main entrance should be numbered using a separate internal numbering sequence.
- Where a building has multiple entrances but continuous corridors then the main entrance door should be numbered, and all units numbered using a unique internal sequential numbering sequence separate to this entrance door number.
- Multiple floor buildings which form part of a broader building complex will be numbered from the stair core used to access the building. Where there is more than one multiple floor building, the individual buildings should be numbered to the street and internal sub-divisions in the building numbered into that building, for ease of location.
- Mezzanine floors should be linked to the floor providing access to the mezzanine floor for proper identification. For example, if the mezzanine floor is a sub-division of the first floor it should be described as ‘First floor mezzanine: 1 to 20’ or ‘Level one mezzanine: 1 to 20’. The building signage should also describe this sub-division.
- Numbers within an individual building should be unique. Care should be taken where a building has multiple entrances and access corridors, as corridors on different floors may access different wings / areas of the building. To avoid confusion where a unit can be accessed from two entrances with different external numbers, internal numbering may be applied consecutively through successive entrances, for example:
- Flats 1 to 10, 10 High Street
- Flats 21 to 25, 14 High Street
- Flats 11 to 20, 12 High Street
- Flats 26 to 36, 1 Side Street
- Where the latter is a wing of the same building accessed from a different street.
- In extreme cases where no street numbers are available including numbers with a letter suffix e.g., 15A. A building name should be used with the appropriate building name suffix, see building suffixes
- In all cases suitable external signage detailing which units are located on each floor or level should be erected in either case and be readable from the street. This aids the emergency services as they can quickly determine which floor the unit is located. The minimum size of all signage characters should be 62.5mm which should be displayed in a clearly readable position facing the street.
- Ground floor: 1 to 20
- Second floor: 201 to 220
- First floor: 101 to 120
- Eleventh floor: 1101 to 1120