I am often asked by people who want to find out how old their house is. There are several methods depending on the approximate age of your property.
In the Medway Towns there are books called Kelly's directory that are held at local libraries. These detail all the properties and owners in particular areas and can show when new houses appear in the records. For example many houses around Maidstone Road in Rainham sprung up in the late 1920s and early 1930s and can be seen from the volumes of Kelly's Directory from each year.
If you property is much older than this then parish records or census returns could be a good starting point. For newer properties local councils may hold records that show when the house was built.
If you have any more suggestions for ways to determine how old your house is then please leave them as comments.