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Making Castle Drogo watertight
Our restoration project will make Drogo watertight for the first time in its history. Without this work, a national treasure will be lost forever.
Plans to preserve the castle include the renovation of the massive flat roof structure using cutting-edge techniques to make it permanently watertight.
This will be conservation on a grand scale; the roof area is roughly equivalent to two international football pitches. A high-tech roof system, designed by Bauder will be installed. This two layer membrane is designed to cope with the extremes of temperature experienced on Dartmoor.
In order to lay the new waterproof system, 2,355 granite blocks weighing 680 tonnes will have to be removed and then reinstated. This will involve moving and reassembling entire battlements and large sections of the castle walls.
We’ll also have to redesign the roof gullies to accommodate the heavy Dartmoor rainfall.
In order to make the castle walls watertight, the cracked cement pointing will need to be removed and replaced with an improved lime based mortar. The sheer amount of new pointing required stretches to an impressive 60,000 metres (laid in a line it would stretch all the way from Castle Drogo to Lundy Island).
In addition some 913 windows containing over 13,000 panes will be cleaned and the lead replaced to stop them leaking.
Trouble on the battlements
Castle Drogo’s medieval-style flat roof has been its Achilles heel. Lutyens had attempted to seal the roof using asphalt, a relatively new and untested material for the time, but it was prone to cracks caused as the temperature rose and fell. Before the building was even finished, it had begun to leak.
More than just a leaky roof
Drogo’s problems are more challenging than just a leaky roof; the castle is under siege from all sides. Rain water is being blown in through the cracks in the mortar-where the cement has not properly stuck to the granite stone. This is driven in by the blustery moor-land winds.
In through the windows
The windows have been another major weakness for Drogo. In keeping with a medieval fortress, Julius Drewe had demanded that there were no windowsills. Now that the window surrounds are decaying with age, they provide easy entry for water into the castle.
The thick castle walls and poor ventilation have caused serious problems. Moisture condenses on the cool concrete becoming trapped inside the building. This causes the steel beams to rust and expand, shattering the surrounding concrete.
Proving it works
In 2007 we tested this solution on the chapel, a part of the castle badly affected by water damage. The large windows were restored and the Bauder roof system introduced, the chapel is now watertight.
A unique visitor experience
We are open throughout the building-work, offering a once in a lifetime opportunity to explore Drogo as you’ve never seen it before.
Discover rooms never before open to the public, head out onto the roof and wander around our brand new exhibitions.
Working with the local community
This project is an opportunity for Drogo to become central to local life, from using the grounds for communal events, to offering apprenticeships, training placements and new voluntary positions. There are great educational opportunities for school trips.