Heavitree Stone is not just used in the historic buildings of Exeter, but in many boundary walls around the city.
Along Wonford Road, between the Nuffield Hospital and Lyndhurst Road, there is about a third of a mile of walling with some good examples of different stone, dressing, and building techniques. Much of it is Heavitree Stone, and highlights some issues with pointing and facing! In some of the sections, you can see problems with the sort of cement used and the way it has been applied. As the stone has weathered back, the joints now stand out, and this accelerates the erosion.
The junction at Victoria Park Road shows well how much Heavitree Stone can weather. Different stones weather in different ways. For example, limestone is mainly calcium carbonate, and reacts with acid rain in areas of air pollution. This is chemical weathering. Heavitree Stone is subject to physical or mechanical weathering. Physical weathering can be due to rock expanding and contracting under extremes of temperatures. This is less likely in Devon’s temperate climate. In the UK, the most common type of physical weathering is by continued freezing and thawing. Water gets into joints and cracks, and expands when it freezes, forcing the stone apart. Heavitree Stone, with its gravelly texture, has plenty of small cracks!