Cowley Manor: an old swimming pool becomes stone-clad hotel space

A new bedroom extension at Cowley Manor, a country house hotel in the Cotswolds, places a contemporary masonry pavilion on the site of a long-lost ballroom. It features a structural timber frame and solid facades built using local stone to minimise environmental impact, with the arched and scalloped stone bays offering a contemporary reinterpretation of the main house's Italianate frontage. 

Inside, five guest rooms feature timber-lined walls that reimagine the carved wood panelling, long since lost, that would have adorned the lavish reception rooms of the original house.

How did De Matos Ryan come to be involved with this extension to the Grade II-listed country house hotel?

De Matos Ryan was first involved with Cowley Manor back in 1999, when new owners wanted to turn it into a hotel. At the time, it was a nursing home. 

Historically it had been the home of James Horlicks, of bedtime drink fame – it wasn’t built for him but he invested in the property, doubling the size of the house and adding a ballroom. In 1928, under new owners, the ballroom was demolished to create a courtyard swimming pool and terrace, later filled with gravel and fenced off when the property became a nursing home. 

We carried out a complete reimagining of the manor house, to create a country house hotel within the 22 hectares of Grade II*-listed parkland.

How did you decide on the location for the new pavilion at Cowley Manor?

Post-pandemic, the owners wanted to add more family rooms. We suggested a pavilion on the site of the former swimming pool, which we felt was possible from a planning and conservation point of view. The Cotswold stone walls of the swimming pool courtyard had also been built incorrectly, causing them to spall so badly they were impossible to repair. 

The conservation officer wanted the courtyard walls taken down and built afresh. Our view was that this was rebuilding for the sake of rebuilding – it would have been a costly, unsustainable exercise without adding value to the building. So, rather than rebuilding the stone wall, we set out to build a new building that would complement the character of the listed manor. 

We gained permission to erect a two-storey pavilion using the swimming pool’s footprint. In 2022 the hotel was sold to the Experimental Group, which gave us the go-ahead for the extension.

How do you overcome the challenges of building on the site of a former swimming pool?

There are concrete ground beams that span across the former pool, part-supported on the original structure. These support a new concrete ground floor slab supporting a relatively simple two-storey structural timber frame of sustainable, UK-sourced Douglas fir. 

Designed by Price & Myers, the timber is married with structural steelwork portals at the ground floor front to support the stonework wall of the floor above. It would have been easier to use steel throughout, but we wanted the building to have a sustainable, low-carbon, natural aesthetic. The frame was prefabricated at Timber Workshop’s Devon premises, brought to site and assembled in about eight days. It is independent of the outer stone box in terms of differential movement.

Why did you opt for solid stone walls?

The stonework is, in effect, a ready-made, low-energy material, which forms the building’s self-finished and self-supporting external skin. Initially, from a cost point of view, we proposed building the pavilion in cast stone. But the conservation officer was against that approach. Their view was that the pavilion was integral to the existing building, which was built from solid stone, and that the pavilion should be constructed in the same way. In hindsight, I’m pleased they thought so.

On a sunny day, light and shadow play on the pilasters and carved arches of the original building’s facade. We wanted our building to have depth too, so the front and side walls on the first floor feature scalloped bays complete with solid stone, load-bearing, arched openings at the front supported on solid stone piers. This is not thin cladding – some stones are more than 500mm deep.

How are the walls constructed?

From ground to the first floor parapet, the walls on all four sides are full-filled cavity construction, consisting of a self-supporting stone outer leaf tied back through insulation to a blockwork inner leaf, which carries the loading from the upper stonework walls.

Above the parapet on the first floor there is no blockwork inner leaf, so the scalloped stonework of the front and side outer walls is supported on 650mm deep coping stones set on top of the parapet wall. Here the stonework is tied back to the timber frame. There is a gap between the stonework and the Tyvek membrane that wraps around the insulated timber construction of the inner leaf.

Scalloping the pavilion’s upper walls and pulling them back from the perimeter to create a first floor balcony made our lives harder, so the arches are built up from precast concrete beams supported by the steel-strengthened portal sections of timber frame. 

The ground floor walls are flat. The stonework arches are self supporting, but the blockwork inner leaf is supported above the arches on concrete lintels. At the rear, we took down the spalled stone courtyard wall and put up a new blockwork wall, stone-faced to cut costs.

Where did the stone come from?

This is a solid masonry box driven by planning. Having to work with stone made us think this could lead to a more sustainable building. Farmington Masonry used stone sourced from the nearby Hartham Park quarry. It had the CNC technology to shape the stonework and the masons to install it. We didn’t do embodied carbon calculations because there was no other material option and no quarry closer that was able to supply the large-dimensioned blocks.

The stonework is contractor-designed – how much input did De Matos Ryan have into its appearance?

Call us control freaks, but we drew every stone. One of the things we were keen on was that this building related to the main building. When they first extended the manor house, they did not change the stone coursing. Our building follows the same course lines as those of the existing building. The stone’s vertical rhythm is also based on the existing – as are the quoin stones of the arches. 

The stonework contractor’s fabrication drawings did include some slight modifications, but these were only to make construction of the wall more straightforward. 

With so much stone, how did you meet Part L of the Building Regulations?

The building is highly insulated. The thickness of insulation exceeds that required under building regulations. The envelope’s thermal performance is calculated up to the Tyvek membrane. The solid stone wall, meanwhile, is simply an outer shell.

Why line the rooms in timber?

Historically a lot of the rooms in the original house were timber panelled. In trying to move away from the generic and ubiquitous plasterboard/painted wall finish for our low-carbon timber-framed building, we decided we wanted a timber internal finish without the need to paint, decorate and skim. 

The walls are finished in maple-veneered engineered plywood. Birch ply provides the decorative finish between joists. All the timber is finished with a Class O-rated Envirograf clear intumescent paint coating. This does add a slight white tint, which helps unify the different timbers used.