How they Kept the Keep

Astley Castle’s much-praised reinvention is a technical triumph as much as an aesthetic one

If refurbishment were a sport, the Stirling Prize-nominated reinvention of Astley ­Castle would be firmly in the full-contact, all-in wrestling category. Witherford Watson Mann’s (WWM) robust rehabilitation of this Warwickshire ruin has boldly transformed a 12th century wreck into a popular holiday house that’s fit for the modern visitor, yet nonetheless remains a partial ruin.

‘We never went down the “touch it ­delicately” route. We went into this ruin and pushed it strongly,’ says WWM director ­Stephen Witherford.

The architect won a Landmark Trust competition for the project in 2007 with a £1.35m scheme that, instead of holding the Grade II * listed ruin at arm’s reach from any new build, directly inhabits the oldest part of the site and uses the new work as a graft to bind the ruin together and halt its decline. ‘How­ever romantic, a ruin is not a natural state for a building,’ says fellow director William Mann.

WWM was clear that there would be no attempt at scholarly restoration back to a particular era of ruin. For a start, the castle was no single ‘old’, but the result of 800 years of interventions. It began as a defensive stronghold with walls nearly 2m deep, underwent significant expansion in the 15th, 17th and 19th centuries and was finally burnt out in the 1970s and left roofless. Instead, this ‘new’ is another, clearly legible episode in the building’s life that makes no attempt to ­cover up what Witherford calls the ‘catastrophe’ of its past. Yet it moves on positively to set up what WWM terms a ‘conversation’ between old and new.

A physical model of Astley Castle followed by WWM’s 3D modelling of its intervention. Used to create a subsequent physical model of both the brick and timber elements, the whole was ultimately inserted into the 1:50 model of the ruin.
A physical model of Astley Castle followed by WWM’s 3D modelling of its intervention. Used to create a subsequent physical model of both the brick and timber elements, the whole was ultimately inserted into the 1:50 model of the ruin.

The first step, stabilisation, was no mean feat, says David Derby, partner of structural engineer Price & Myers. At the start of the project the ruin was so far gone there were doubts that it could be saved – although most of it was in the end, except for the relatively ­flimsy Victorian additions. The east of the house, so atmospheric now as courtyards, was completely filled with vegetation and rubble and in danger of collapse. A new roof was urgently needed to prevent further deterioration.

Price & Myers cleared the debris and used props and resin anchors to stabilise the castle initially. The key to the permanent structural solution lay in how the architect chose to use the ruin. After grappling long and hard with the site to make sense of its past and potential future, WWM made two main moves concerning location and configuration. It opted to colonise the 12th century section for residential accommodation, extending on the ground floor into a 19th century addition to the west. The scheme also adapts the immediately adjacent ruins to give two partially roofed courtyards that function as external social spaces.

Lateral thinking on how to protect the inner face of stonework resulted in a partial timber roof, creating a Roman atrium above the courtyard.
Lateral thinking on how to protect the inner face of stonework resulted in a partial timber roof, creating a Roman atrium above the courtyard.

Next, WWM decided to invert the accommodation with four bedrooms and two bathrooms on the ground floor and a grand living space and kitchen on the first, with views down into the courtyards. The great gashes in the ruin were used for full-height glazing on the south and east to create a surprisingly light castle interior. The lack of surviving north wall eased the task of accommodating kitchen and bathroom servicing.

This transformation was navigated with a clear material approach – brick and concrete to strengthen and infill the primary ­masonry structure of the ruin, and laminated timber for the relatively independent secondary interventions needed to make the residence – the roof, staircase and room partitions. The result is 60% old, 40% new.
WWM’s new brickwork (see box) plays a huge role in the project, creating massive brick piers which fill the voids in the walls and frame new windows. This buttressing and binding structure, says the architect, is like a new ruin being integrated into the old.

Laminated timber structural joists are crisply detailed at their interfaces and create the upper living level.
Laminated timber structural joists are crisply detailed at their interfaces and create the upper living level.

Nothing was easy. Installation of steel reinforced concrete lintels was particularly tricky, made harder by the presence of a moat that limited crane access. To make craning possible, larger lintels were hollowed out to ­reduce their weight and, once positioned, filled in-situ to give them structural strength. The largest is a 7m long, 600mm T-shaped lintel with a 200mm visible ‘boot’, positioned above the full-height windows along the ­middle spine wall where the eastern 15th century wing meets the core.

Windows are set deep in the masonry so that externally, you see the void in the wall rather than the glass on the surface. The large new openings take their inspiration from the rhythms of the surviving Gothic mullions and are stepped in plan with a laminated perpendicular pane to ­create a partial Juliette balcony, and break up the ­reflecting plane.

Distinctions between the old and new structures, using timber and Danish brick, bring new materiality and language to the old ruin.
Distinctions between the old and new structures, using timber and Danish brick, bring new materiality and language to the old ruin.

Bolstered by the pier infills, the now-­stable walls had enough capacity to take a new, stained pine roof. The massive 7m spans in the living room suggested use of laminated timber; this was brought to site and installed in a grid of primary and secondary structure using traditional carpentry to hide the joints with some steel plates where necessary. Together with the timber partitions, floors and stairs, this joinery creates the warmth and ­intimacy necessary for its domestic use adding a softness to accommodate awkward bits that don’t align. Services and cabling are­ easily concealed within partitions of hollow stud construction, faced with dense fibre panels for sound and fire resistance. These are finished in birch plywood with sycamore beading and skirting. Floors are oak block with terracotta borders to separate the wood from the original walls, which have yet to ­finish drying out.

For the two courtyards, the challenge was to protect the insides of the walls from the weather while retaining them as open spaces. The solution was a new partial pine roof in each, with Roman atrium-like central openings. This tactic enabled the architects to rebuff the Trust’s original desire to limewash the inside of the courtyards. Instead, the texture and character of the uneven ­inner walls are retained. Any rain that comes through simply drains away through the brick paving and gravel aggregate floor.

As well as retaining an overall clarity of philosophy towards the old, the architect had to respond intuitively to suit the constant challenges of the highly particular conditions. For example, how on earth, as Mann says, do you get a contemporary kitchen into a Medieval ruin without hitting a bum note? The answer was by creating a kitchen niche for the ‘hot’ functions within the rebuilt north wall using smoked oak units with Spanish terracotta tiling. ‘Wet’ functions are accommo­dated in a separate island unit.

The architect says with some justification that photography cannot do justice to the ­nuances of this reoccupation project. It might be a long shot for it to win the Stirling Prize, but when the judges visit this month to ­experience it for themselves perhaps they too, like many of the visitors to Astley Castle so far, will fall under its spell.


Picking the brick

For such a very English ruin, purportedly once home to Lady Jane Grey, it’s ironic that the 49,800 bricks used to bind the wreck together are Danish. Petersen Tegl’s charcoal-fired D36 were chosen for both their hue and narrow 37mm height, which allowed the architect to build finely and closer to the ruin. 

The bricks form piers with the same dimensions as the walls they buttress – 600mm to 1800mm. A diaphragm pier construction of clay blocks binds the inner and outer skins, tied in by a header at every fourth course. This hollow inner structure is backfilled with aggregate so new and historic elements move similarly, avoiding the need for movement joints. Around this structure is the outer face of bricks, laid on a quarter lap rather than half, to avoid a relentlessly mechanical bond. Joints have a lime-stabilised fill with thermal and movement characteristics close to the original and are spaced at 18-20mm to match the join with the old. Where new abuts old, hidden stainless steel ties link the brick to the existing masonry. 

The D36 brick has a range of tones from pink to green that together are closer to the existing sandstone than the grey/green brick WWM initially chose. The resulting, combined infill brick pier/existing masonry wall structure is built to roof level and has the strength to accommodate the new concrete lintels, and support the laminated timber roof.


 

Credits

Client The Landmark Trust 
Architect Witherford Watson Mann Architects
Structural engineer Price & Myers
Quantity surveyor and contract administrator Jackson Coles 
Outline services design Building Design Partnership
Approved inspector Oculus Building Consultancy 
Main contractor William Anelay

 

Suppliers

Bricks Petersen Tegl
Precast concrete lintels and copings Cambridge Architectural Precast
Laminated timber Dunscar Timber 
Low iron glass Pilkington 
Roof coverings Bauder 
Terracotta tiles Fired Earth/San Genis
Quarry tiling Ruabon 
Engineered wood block flooring Junckers
Engineered oak flooring Ted Todd 
Ironmongery Ize 
Lights Manufactum
Stove Charnwood 
Lye and wood oil Dane Care
Woodstain Sikkens