An exceptional 11m × 5.5m reinforced-concrete indoor pool within the grounds of Grade II listed Dane Chantry, alongside a spa, sauna and entertaining space. XL Pools took over the evolving project following the breakdown of the previous contractor relationship, ultimately delivering a modern wellness environment beneath an extraordinary 10m double hammer-beam oak structure, combining contemporary pool engineering with traditional craftsmanship.

The Petham Project deserves to win because it is difficult to imagine another residential indoor swimming pool quite like it.The pool sits within the grounds of a Grade II listed property incorporating a 12th-century Chantry and 16th-century manor house, beneath an extraordinary double hammer-beam oak structure spanning approximately 10 metres without internal support posts. Inspired by one of the great engineering achievements of medieval architecture, the structure is understood to be the first known building of its type constructed for more than 200 years. To create a modern indoor swimming pool beneath it presented an exceptionally rare design opportunity.XL Pools also did not inherit a straightforward project. We became involved following the breakdown of the client's relationship with the previous contractor, at a point when many important decisions remained unresolved. The client did not have a predetermined vision for every finish, product or practical detail, so our role developed far beyond simply building a pool. We became a long-term technical adviser, helping guide the project from an uncertain starting point through to completion.The finished space demonstrates what can be achieved when modern pool engineerin

The challenge was to create a contemporary pool and wellness space that respected Dane Chantry’s remarkable historic setting, including its 12th-century Chantry and 16th-century manor house. With no fixed brief, XL Pools became a trusted adviser, guiding the client through finishes, equipment and practical decisions as the project evolved. The pool sits beneath an extraordinary double hammer-beam oak structure, spanning approximately 10m without internal supports. Waterford Cream finishes continue from the pool surround into the water, complementing the oak, exposed brick and flint and connecting the pool with the spa, sauna and entertaining space. Our design input also addressed details not originally considered, including a bespoke stainless-steel cover roller beam, handmade locking pit lids and an Alucore undercroft access hatch. These solutions ensured the exceptional aesthetics were matched by practicality, accessibility and long-term maintainability.

The 11m × 5.5m freeboard swimming pool was constructed in reinforced concrete to BS EN 1992 (Eurocode 2). With depths ranging from 1.1m to 2.2m and an approximate water volume of 100m³, the pool required a robust hydraulic and treatment specification capable of maintaining excellent water quality within a substantial indoor environment. Filtration is provided by a Zodiac MS800 36" media filter paired with a Zodiac FloPro 2HP single-speed circulation pump. The system delivers approximately 20m³/h circulation flow, achieving a five-hour turnover with a filtration rate of approximately 43m³/m²/h. This combination was selected to provide reliable filtration and consistent circulation across the large pool volume. Hydraulic circulation comprises three Certikin surface-water skimmers, two Certikin stainless-steel grille bottom drains and three Certikin return outlets. Suction and return lines have an internal diameter of 55mm, providing the required flow while maintaining appropriate hydraulic performance. Water treatment is automated using a Hanna Instruments BL-122 pH and chlorine dosing system, selected to provide continuous monitoring and accurate chemical control. This is supplemented by a Filtreau Titan 80W UV system, providing secondary treatment to enhance water quality, assist chloramine reduction and optimise chemical consumption. Environmental conditions within the pool hall are controlled by a Heatstar XF EC 3000 Super Plus. Effective humidity, air-temperature and condensation management were essential due not only to the substantial pool surface area, but also to the extensive oak structure and historic materials surrounding the pool. The Heatstar system provides specialist environmental control while helping protect the building fabric and maintain comfortable year-round conditions. Heating for the pool and building is provided through the property's ground-source borehole heating system alongside NIBE equipment installed by the client's specialist contractor. The use of ground-source technology provides an energy-conscious solution appropriate to a pool and leisure environment of this scale. A Technics & Applications Alu-Look solar slatted cover was specified to significantly reduce evaporation and heat loss when the pool is not in use. Integrating the cover required bespoke engineering by XL Pools. We fabricated a stainless-steel roller beam and handmade locking pit lids incorporating nylon bushes, creating a reliable mechanism while maintaining access for future servicing. An additional challenge was access to the undercroft. This requirement had not been fully considered within the original design, but our experience identified that practical long-term access would be essential. XL Pools therefore designed and constructed a bespoke Alucore access hatch, allowing efficient future inspection and maintenance without compromising the surrounding finish. The technical complexity extended beyond the pool itself. XL Pools inherited the project following the breakdown of the client's relationship with the previous contractor, with numerous decisions and details still unresolved. We had to work within extensive structural-engineering requirements, coordinate with multiple specialist contractors and develop elements of the pool specification progressively as the wider building evolved. Particular care was required around the exceptional double hammer-beam oak structure. Major construction milestones were carefully inspected and validated before subsequent works progressed, requiring flexibility and close coordination throughout an unconventional programme. The completed installation successfully integrates reinforced-concrete construction, carefully considered hydraulics, automatic chemical control, secondary UV treatment, specialist environmental management, renewable-energy heating and bespoke engineering within one of the most unusual residential indoor pool environments we have worked on.

XL Pools Ltd