Thursday, 21 February 2019

Building a Castle: Stone

The most obvious material needed for building a castle is stone, but not just any stone and not all the same kind either. The best stone was dressed and used around windows and doors and for special features. The general stone was for the walls, and even the offcuts and poorer quality stones were used to infill between the double walls and for paths. Nothing was wasted.
treadwheel crane
The huge quantities of stone required posed another problem - how to shift it. Unless the castle was located near a source of stone, it had to be transported, sometimes over long distances, by carts and barges. It also had to be moved around the site, requiring pulleys and winches to lift the stones as the structures grew.

The master mason not only had charge of the whole project but needed his particular skills to choose the correct stone and see it was properly treated.

Splitting Stone

Part of the expertise of quarrymen was in identifying different types of rock and the different methods of handling it.
sandstone in Colorado
Soft limestone would be hit with a mallet to create a crack and then wooden wedges inserted into the crack and soaked with water. As the wood swelled, it would widen the crack until it split.
limestone in Krakow Poland
Harder rock like sandstone and granite was also split using wedges, but metal wedges were driven into natural fractures to split the rock.


The castle site at Gu├ędelon was in an old sandstone quarry, providing the major building material on site. The sandstone came in three colours:
Yellow is the softest sandstone and not good for building, so was used for infill.
Red sandstone is of medium hardness and used for facing stones.
Blue sandstone is the hardest and most difficult to work. It was used for load bearing, like lintels.

[adapted from The Medieval Castle Haynes Manual by Charles Phillips and The World of the Castle website]

Ann Marie Thomas is the author of four medieval history books, a surprisingly cheerful poetry collection about her 2010 stroke, and the science fiction series Flight of the Kestrel. Book one, Intruders, and book two Alien Secrets, are out now. Follow her at

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