Kentish ragstone is a building stone that has been used – both historically and currently – throughout South East England. It is a hard, medium grey, sandy limestone from the Cretaceous era (and so is a ‘young’ limestone) that is quarried in Kent from the Hythe Formation of the Lower Greensand group.
In appearance, it has a rough, course texture that is difficult to work, so even carving square blocks can be difficult. For this reason, it does not tend to be suited to fine stonework; consequently, it is sometimes used for infilling a wall that is faced with a ‘fairer’ stone. However, due to the scarcity of good stone in the South East, it has become a very familiar building material in Kent and the neighbouring counties.
 Historical use
Historically, Kentish ragstone was quarried primarily around Maidstone, Kent, from where it could be easily shipped on barges down the River Medway, then carried up the Thames to places as far as Eton and Windsor.
The Romans used Kentish ragstone for the walls of Londinium. During the medieval period the material was in much demand in London for churches and engineering works such as river walls. It was also used on the Tower of London, Rochester Castle, the medieval Guildhall, London and Westminster Abbey, as well as numerous churches in Kent.
One of the most celebrated examples of Kentish ragstone is Knole House, near Sevenoaks, Kent, built in 1456, where the material is seen extensively for window surrounds, string courses, copings and finials, all demonstrating that it can achieve a good finish if carefully chosen.
Possibly due to its hard, uncoursed, irregularly bonded and rubble-like consistency, Kentish ragstone remained a favoured building stone for Victorian churches. However, the course, uneven texture may attract dirt which can mar the aesthetics.
Today, Kentish ragstone is still used in Kent as a vernacular material for building and repair work but its use in surrounding regions is generally limited due to the difficult processes involved and the variable nature of the material. As a result, it is sold by the tonne and can be used for gabion walling, as a general construction aggregate, and for resurfacing paths.
 Related articles on Designing Buildings Wiki
- Choosing stone.
- Defects in stonework.
- Finding stone to conserve historic buildings.
- Inspecting stone sample panels.
- Limestone for building.
- Modern Stonemasonry.
- Natural stone cladding.
- Natural stone.
- Portland Stone.
- Sourcing stone to repair Exeter Cathedral.
- Stone dressing.
- Tufa and tuff
- Types of stone.
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