Caring for Corfe Castle

Maintenance and conservation work is essential for all historic buildings, and the ruins of Corfe Castle are no exception. As a Scheduled Ancient Monument and Grade 1 Listed Building, the castle holds international historical significance and we have a legal responsibility to preserve it.

We take a conservation and preservation approach to the works, minimising disturbance to the historical fabric of the castle but doing enough to slow further deterioration.

Regular maintenance helps address ongoing deterioration from vegetation growth and weathering, however, we have seen an acceleration of deterioration in recent years due to climate change. Extreme weather has impacted the fabric of the castle. Periods of drought have dried and weakened the mortar holding the stone together, while heavy downpours and vegetation growth have caused further damage..

The castle’s history is taught as part of the national curriculum. and the works are crucial to ensure future generations are able to learn from and enjoy the castle.

One of the most significant challenges with undertaking work to Corfe Castle is access. Perched on a hill, 43m above the valley with steep gradients, Corfe Castle was designed to be impenetrable.  Specialist contractors will abseil down the castle walls and, while suspended at height, carry out the works. There will also be some need for scaffolding in many areas.

The site's sheer size is another challenge. Most of the masonry throughout the castle needs work, from the gatehouse at the entrance to the top of the Keep.

The project will progress in three phases, over three years and will cost £2 million. Most of the project is being funded by The National Trust and a generous grant from the Wolfson Foundation.

We also need to raise £100,000 from supporters. Every visit, membership and donation helps us to care for this special place.

Repointing involves repairing and replacing damaged mortar, the binding material between stones. It is crucial to maintain the stability of the walls to prevent water from infiltrating. Corfe Castle was built with lime mortar, and we ensure the correct mix is used through careful analysis of the existing mortar, and sourcing clay from an original quarry.

Some types of vegetation can damage the castle's fabric. Ivy and valerian, for example, can take root in cracks and crevices within the damaged walls, weakening the structure. Removing these plants is an ongoing challenge. Our dedicated staff can only reach so high, so specialist conservationists are brought in to remove vegetation from inaccessible areas, ensuring the masonry remains secure.

Not all vegetation is harmful, however. Ivy, for instance, can be very effective at protecting the underlying stone from extreme temperatures and weather. It also helps prevent airborne pollution from degrading the stone. We strike a careful balance between removing the damaging ivy and maintaining the ivy that helps protect the castle.

Harling is a technique involving the application of a lime mortar finish to protect the exposed internal core of the walls. Over time, this mortar deteriorates and needs reapplication.

Hearting involves using small stones to fill gaps between the external stone layers of the wall, with larger stones at the bottom and smaller ones at the top. Over time, these stones and the mortar can come loose. Part of our conservation work is to reinstate missing hearting.

Despite our best efforts, periodically stones can come loose. Dedicated staff undertake regular inspections where any loose stones are recorded, carefully stored, and kept safe until our specialist stone masons can restore them to their original positions.

We use soft capping, a technique using vegetation to protect exposed wall tops. It prevents rainwater and moisture from damaging the walls while allowing moisture to escape, protecting against freeze/thaw damage and erosion. Soft capping also adapts to a changing climate, continuing to protect the castle for generations to come.

Corfe Castle still boasts many significant historic elements, including a surprising amount of decorated plaster which needs looking after. Some elements of the castle have never been exposed and studied and the conservation works offer exciting opportunities to uncover and learn more.