A river runs through it
Ballihoo makes heads turn. Sited on the Oxfordshire bank of the River Thames at Caversham and visible from Caversham Bridge, from the towpath on the Berkshire side and from passing river craft, it is an assertive and dramatic new presence.
For the owners the views are impressive, too. From the first-floor living room, huge picture windows give a grandstand view of river traffic and superb vistas up and down river and over the Thames floodplain.
Ah yes, the floodplain. Despite the narrowness of the site, which rises from a narrow level strip by the river up a steep bank to a road at the rear, there was no question of major encroachment onto the floodplain. That the site could be built on at all stems from an established residential use. An inhabited boathouse had been on the 1ha site for over 30 years and Reading Borough Council, the local authority, was prepared to permit a new dwelling which was innovative but still in character with the river setting.
Precedent helped with the Environment Agency too, which granted a license to overhang the river by the same distance as the previous building.
The lifestyle brief was for a modern, flexible home for an active young family, exploiting the river setting and giving easy access to the water. The design responds to the brief and to the site constraints by taking the building off the ground and over the water.
A re-interpretation of the decorated boathouse archetype, it stands on six pairs of massive piers which support the steelwork frame, the focal first-floor accommodation and full-width balcony, cantilevered out over the river and large boatdock. The pitched, tile-clad timber roof has deeply overhanging eaves, producing a floating effect.
From enclosure into openness
From the road entrance approach, Ballihoo reveals its surprises only gradually. A wooden fence screens the garden from public view and only a deeply recessed front door pierces the gable wall forming the entrance elevation, generating a modest, chapel-like appearance.
The sequence is one of enclosure and darkness, progressively opening out to light and lateral views. The axial route from the street entrance to the piano nobile leads past the kitchen, utility room and stairwell before expanding into the large, open-plan living area arranged around a central fireplace.
Light floods into this magnificent space through full-height windows on the three aspects. The south window opens onto the full width of the site, 4.5m above the river.
The ground-floor is raised 1.3m off the ground with a 1m high void below to allow floodwaters unimpeded passage across the site. A stepped bridge from the stair hall gives access to the rear of the boat dock.
The back wall retains the steep bank at the rear of the property and a separate twostorey garage and games room is also built into the bank.
James' original design concept involved a large steel frame with a cantilever deck.
However, with the lateral wind load anticipated, this would have entailed too cumbersome a frame - hence the masonry pier solution. These simple and powerful verticals are set on concrete-filled steel drum piles in the alluvial clay and carry the steel members, which are expressed at first floor and second floor levels.
The 6.7m high columns, in brick-faced loadbearing blockwork, are 1m deep x 1.7m wide at their base, reducing via successive plinth details to 1.1m wide at roof level.
A former associate of John Outram, James is alive to the innovative potential of brickwork. A blend of orange-red stock bricks was chosen as the main brick, with blue engineering bricks for the first few courses in the piers, which seem to ground them to the riverbank. It's a formula altogether sympathetic to Reading's brickwork tradition, but in a modern, stripped-down manifestation. Little is allowed to detract from the rhythm, drama and sculpted quality of the piers.
Openings are marked with projecting double creasing tiles, with brick on edge at heads and with canted brick sills. The brickwork was not without challenges for the bricklayers - particularly with the setting out for each pier: there was a mere 3mm tolerance.
Ballihoo has made this stretch of river more exciting, but it also had to meet more workaday requirements. Despite the large window expanse, a SAP rating of 97 has been achieved through a combination of southerly aspect, doubleglazing, the thermal mass of the masonry, efficient insulation and a condensing boiler. U values for the brick walls are 0.27, and for the roof 0.21.
Ballihoo should stand the test of time and whatever the river itself can throw at it - James is extremely keen to see the Thames floodwaters rise high enough to batter against those giant columns. And lose the fight.