Building (or house) numbers are very important elements within most postal addresses, ensuring of any mail, but also for data processes such as de-duplication and postal validation.
The way that buildings are numbered varies within populated places, within countries and within regions.
Numbering methodologies
There are several different numbering methodologies in use.
Assigning ascending odd numbers on one side of the street and ascending even numbers on the other. This system is common in Europe.
Assigning numbers consecutively on one side of the thoroughfare then continuing the same sequence on the other side of the thoroughfare. This is often found on squares.
Assigning a number on the basis of the distance along a street. The numbers of buildings contructed on grid-patterned streets may jump at the start of each new block so that the numbers on that road in that block always begin with with same hundred or thousand number. For example, the buildings on one block may go from 501 to 563 and then the next building on the new block will be 601. With this system all existing buildings on a thoroughfare do not need renumbering if new buildings are constructed in the gaps. It also means that numbers can be high (5 figures or longer). This system is found in Australia, New Zealand and the USA.
Assigning a number to a block and to a building within a block on the basis of the order of construction. This system is found in Japan.
Assigning a number to a block and to a building within a block in a sequence around the block.
All buildings within a district may be given a unique number within that district. This system is found in Venice, Italy.
Numbers may be assigned on the basis of the kilometre distance from a given point along major roads. This system is common in Italy.
All buildings within a small village may be given a number unique to that village. This system is common in Southern and Eastern Europe.
Buildings may be numbered according to a cadastral register, as in the Czech Republic and Slovakia.
Buildings constructed after building numbering has been assigned may, depending on the methodology used, be given a new number (related or unrelated to those numbers used in the buildings around it) or a number related to the number used in a neighbouring building followed by a suffix (a/b/c/bis/ter/ etc.). Buildings merged may use one of the numbers used previously, or a range (13-17, 13/15).
Note that no system is used systematically and in a standardised way in any country. There are always examples of alternative and imaginative numbering schemes in certain areas.
A thoroughfare with even-numbered buildings on one side may not necessarily have odd-numbered buildings on the other side.
In this example from near Paris, France, both sides of the street have even-numbered buildings because each side belongs to a different municipality:
Several buildings (or delivery points) on a thoroughfare may share the same number:
A single address with two delivery points. Stralsund, Germany. Photograph: Graham Rhind
Buildings can be numbered with fractions. For example, 102 ½ Elm Road; 97.5 East 7th
A building may have more than one number, for example to indicate its place within a block, to show its position on more than one thoroughfare, or where a boundary runs through it. Examples:
15/F, Cityplaza 3 14 TaiKoo Wan Road, Island East HONG KONG
The border between The Netherlands and Belgium runs through the front door of this house, so it has two building numbers. Photograph: Graham Rhind
Buildings in much of the Czech Republic and Slovakia have two numbers. The first is the číslo popisné (č.p.) (descriptive number), a land registry number, with each building within a district having a unique number. The second is the building number, číslo orientační (č.o.) showing its street address. Photograph: Graham Rhind
Not all street addresses include a building number. They may include a building name or other indicator of location. Examples:
Royal Opera House Covent Garden LONDON WC2E 9DD UNITED KINGDOM
rue de 11 november 1914 23 boîte 17 SBN 2 - Quadra 23 - Bloco 7 - 1o andar 7-4-2 Marunouchi 3-chome 20 Sokak 17/9 2e Egalantiersgracht 17-2 12 5th Avenue # 34
Building numbers are not always all numeric, so cannot be stored in a numeric field. They may, for example, be a number range, or contain a fraction, or a letter: 1-3, 1½, 1.5, 1A.
Example: A house number with fraction and non-numeric addition in Jachenau, Germany. Source: Wikipedia
Paul Plowman has listed many addresses in the United Kingdom where the building contains a fraction here *
Building numbers may start with one or more zeroes. In this case, in Portland, Oregon, USA, the zeroes are an integral part of the building number and cannot be dropped without creating duplication (e.g. numbers 016 and 16 below)
In Fair Lawn, New Jersey, USA, building numbers may be hyphenated, and numbers south of Broadway may commence with 0-.
Another example, this one form the United Kingdom:
0 Egmont Road MIDDLESBROUGH TS4 2HT UNITED KINGDOM
0 Egmont Road. Source: Google Streetview
Paul Plowman has listed many addresses in the United Kingdom where the building number is zero here
A building number may be a negative number. For example:
Minusone College Road CLACTON-ON-SEA UNITED KINGDOM
Minusone College Road, Clacton. Source: OpenStreetMap.org
Paul Plowman has listed many addresses in the United Kingdom where the building number is a negative number here
A building with a number may also have a building name used within an address. For example:
Flat 1.4 Ziggurat Building 60-66 Saffron Hill LONDON EC1N 8QX UNITED KINGDOM
Different buildings may share and entrance which may have more than one building number:
Stralsund, Germany. Photograph: Graham Rhind
A single delivery point may serve multiple addresses:
Stralsund, Germany. Photograph: Graham Rhind
A building may not contain an entrance/delivery point:
Stralsund, Germany. Photograph: Graham Rhind
A building with a number written in letters may not be the same as a building with its number written in numbers. For example,
Ten Post Office Square BOSTON MA 02109 UNITED STATES OF AMERICA
is reported not the same as
10 Post Office Square BOSTON MA 02109 UNITED STATES OF AMERICA
A building number may be used more than once in the same street, usually when number series recommence at an administrative district boundary. For example, 50 Ammanford Road, Tycroes, AMMANFORD, SA18 3QJ, UNITED KINGDOM and 50 Ammanford Road, Llandybie, AMMANFORD, SA18 3YF, UNITED KINGDOM are about 4 miles apart on the same road (Google Maps ).
Buildings with the same number may even be next to each other!
443 Manchester Road, Bolton next door to 443 Manchester Road, Salford, UK as explored by Paul Plowman here .
Building numbers can be high, higher than you might expect.
Examples: In the district of Graan voor Visch in Haarlemmermeer the streets do not have names but each building in the neighbourhood is numbered, from 13000 to 19999, providing the highest house numbers in The Netherlands.
A signpost in Graan voor Visch in The Netherlands showing building number ranges. Source: Wikipedia
Building numbering may not follow an ascending sequence (1,2,3,4,5) or an odd/even sequence (1,3,5; 2,4,6).
Example: The house where Sharon Tate was murdered in Los Angeles, United States of America, had the address 10050 Cielo Drive. The next house down was numbered 10070 and the one after that 10090
Example: Paul Plowman reports here that five consecutive houses on High Street, Earl Shilton, Leicestershire, United Kingdom, have the numbers 75, 75A, 75B, 75½ and 75¾.
Example: On Victoria Embankment in London, United Kingdom we see the building number sequence 40, 58, 50, 56, 60:
Building number sequence. Victoria Embankment, London, United Kingdom. Source: OpemnStreetMap.org
Buildings may be numbered differently according to function. In older parts of Florence, Italy, for example, businesses have building numbers followed by R (rossa, red) whereas residential buildings identified as "black" have no following letter, so a street can have two addresses with the same number, distinguished only by the letter R, as in 4 and 4R via del Campidoglio in the screen shot below:
In New York's borough of Queens, numbers include the nearest cross street or avenue followed by a building number:
In Fair Lawn, New Jersey, USA, building numbers may be hyphenated. The number before the hyphen is the block distance from Broadway, for streets running north to south, or the street number for streets running east to west. Numbers south of Broadway may commence with 0-.
In Hawaii, USA, houses have two numbers separated with a hyphen. The first number derives from the state's tax map key and is the same for all properties within a tax map key zone. This is thoroughly explained here (cached version here).
The punctuation within building numbers may be essential for deliverability, and the meaning of various marks may differ between countries. Thus 16/19, 16-18, 16 und 18, 16,18, 16.18 etc. may all mean different things. Punctuation should not be altered or removed during processing.
Processing
Building numbers may be stored with the rest of the address line (in which case it is important to ensure it is written at the correct end of the address - this differs between countries and regions), or separately to improve the erricacy of data processes. Moving or parsing building numbers after data collection is challenging because addresses can contain many numbers, most not being building numbers:
rue de 11 november 1914 23 boîte 17 SBN 2 - Quadra 23 - Bloco 7 - 1o andar 7-4-2 Marunouchi 3-chome 20 Sokak 17/9 2e Egalantiersgracht 17-2 12 5th Avenue # 34
Because building numbers are not always wholly numeric, or be a zero, or commence with a zero, they should not be stored in numeric fields.
Field lengths: because building numbers can be high, or include a range or other (sub-)building information, ensure that the field to store them is long enough
Punctuation should not be altered or removed during processing.
A house number with fraction and non-numeric addition in Jachenau, Germany. Source: Wikipedia
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that five consecutive houses on High Street, Earl Shilton, Leicestershire, United Kingdom, have the numbers 75, 75A, 75B, 75½ and 75¾.
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BBC, July 2013
