Hyssop Project designed and built this wrap-around extension after overcoming several planning hurdles. The project also involved significant structural steelwork and high-end finishes.

We met the owner of this two-bedroom Victorian apartment at the Grand Designs Exhibition. Our client retained Hyssop Project after viewing our extension design for a period property in Kingston-Upon-Thames as its build neared completion.

The side and rear extension to this ground-floor apartment in Saltram Crescent was designed to provide a third bedroom and larger living space, kitchen and bathroom. 

PLANNING

Westminster Council’s planning department required some changes to the initial plans, which we made. When it later specified that a vital corner of the wrap-round had to be removed – so that the extensions would no longer unite – we instead advised our client to submit the application and appeal if it was rejected. 

We were pleased to be granted planning permission for the scheme, subject to the initial conditions. However, some 10 days later the council notified the applicant that this was a mistake, and revoked its decision. Our planning consultant (Smart Planning) advised us that the council could not revoke the permission, so the united side and rear extension was finally approved.

A joint party wall agreement allowed us to gain further internal space on the side elevation, and benefitted the neighbour’s own planned scheme. 

THE PROGRAMME

With the property unoccupied, we were able to accelerate the works, and completed in 27 weeks, incorporating numerous changes to enhance the design as we progressed. 

Hyssop Project procured most of the subcontractors, and worked closely with the kitchen and bathroom designer and microcement contractor engaged by the client.

The property was completely striped back to the ceiling joists and brickwork in most areas, and all internal walls were removed. We demolished the garden party wall and rebuilt the shared cavity party wall in reclaimed yellow stock bricks. 

A structural system had to be devised for the rear garden wall brickwork, which acted as a retaining wall for the higher ground level of our client’s garden. This wall had started to collapse into the rear neighbour’s garden. Eight steel piles were driven into the ground and a reinforced concrete slab with six L-shaped steel plates hooked over the lower section of wall to prevent further movement.

The new foundations were hand-dug. All soil had to be brought through the terraced property. This included spoil from drainage works for the new bathroom, WC, laundry space and kitchen, and also from lowering the floor level in the rear section of the property to improve the ceiling head height.

A significant amount of steelwork went into the existing structure. Two chimney breasts were removed, and later, a third to increase space in the master bedroom. A cranked steel beam and roof structure to the side and rear extension was formed on site by coded welders. This steelwork supported the upper two storeys of the building, which required back-propping while the steelwork was installed.

The roof structure comprised a warm deck with cranked profile and a single-ply membrane roofing cover system. We fitted three Velux central-pivot windows equipped with solar-powered control for the third bedroom, lounge and kitchen. Aluminium bi-fold doors were initially specified for the second bedroom and rear extension, but the client opted instead for black Crittal windows.

INTERNAL WORKS

Once the building was watertight, we built the internal walls. Eclisse sliding doors maximised available space in the bathroom, new (third) bedroom, WC and between landing and kitchen (requiring a fired-rated door). All ceilings throughout the property (except the new cranked profile structure) were fire-proofed to a minimum one-hour rating. They were also sound-proofed using non-combustible mineral Rockwool and resilient bars to reduce impact sounds from the upper apartment.

A wet underfloor heating system was installed throughout the property. Heating pipes were embedded into the screed finish of the new rear section, with retrofit pipe mats elsewhere on the existing substrate.

For the finishes, the client wanted a contemporary high-end look. Light-grey wooden-effect porcelain tiles were laid over most of the apartment’s floors in a herringbone parquet pattern with an anthracite grout finish. New square-edged skirting and architraves were painted with Little Green’s Hicks Blue. The same paint was used for the internal timber doors with a clear water-base floor vanish for long-term protection, and Little Green Flint for the walls,

We installed the bespoke kitchen, which was designed by Such Designs and manufactured by Rot Punkt Kütchen. This features midnight-blue units with marble-effect Dekton Stone worktops. The units were made and appliances carefully selected to fit the space left by the lower level of the cranked-profile roof. A central island was formed for the cooking area with a Falmec ceiling extractor hood vented through the extension’s roof. The island also provides the main seating/dining space for the family. Echoing the large copper under-sink and tap, aged copper sheeting bonded to toughened glass finishes the end cabinets where the kitchen transitions into the lounge area.

ENLARGED BATHROOM

Significant alterations to the bathroom created a larger space. The wall shared with the master bedroom was demolished and propped, before steelwork was installed to support the neighbouring floor. The new opening was enclosed with electrostatic glass to allow natural light from the bedroom windows when desired. 

Other features of the bathroom include: 

• a sky-blue microcement concrete finish to floor and walls (with many niches introduced for storage)
• contrasting copper-finish Gessi brassware 

• Catalano basin and vanity unit offset to align with wall-mounted taps and provide space on the vanity unit

• an ‘on the level’ shower tray creating a waterfall effect as water drains from the shower. 

• a free-standing Victoria and Albert bath with a large copper tower tap and free-standing Catalano toilet supported on Sigma Geberit frame 

• WC with Gessi brassware with a copper finish on Kast deep-blue concrete basin

In the entrance to the garden, we installed cream 600x 600mm porcelain tiles and grassed the remaining areas. The rebuilt shared party wall has weather-struck pointing with a modern Jackson Fencing panel at the rear of the garden.