Studio KAP adds metal-clad extension to Victorian villa in Glasgow

Tell us about the project ​​ 

The project is a modestly scaled one-storey rear extension to a Victorian villa in south Glasgow. It transforms a rear terrace area to create a place of informal retreat and socialising for a growing family of six, which spanned three generations. The clients’ brief was for a new well-lit, relaxing space, with immediate access to the garden for a home-based elderly relative and the wider family to enjoy in different ways including occasional dining for up to 10 people.

The house is a handsome Victorian sandstone villa with a typical four-room plan on two floors, sitting in an elevated position within the Pollokshields Conservation Area. The extension is conceived as a garden room in the tradition of Victorian conservatories. Its light, frame-like character complements the solid presence of the sandstone villa. A sheltered entrance/exit and covered seating area adjoin a new sunny terrace while accommodating the tall arched Victorian stair window of the existing mansion.

What was the planning situation? 

While the existing building is within a conservation area, it is not listed and achieving planning permission was uncomplicated. Several of our previous award-winning extension projects in the same area perhaps reassured the planners that the same appropriate care and attention would be invested in this project. 

Explain the external treatment 

We chose a dark grey colour for the canopy elements, metal cladding and aluminium window frames to complement the blonde hue of the existing sandstone. This allowed the weighty presence of the stone house to remain dominant. The rendered plinth is separated from the roof, prompted by an early realisation that the structure could be configured to release the bay window from any structural role (most of the steel structure is bolted to or built into the existing rear wall maximising its latent structural capacity). Glazing this column-free perimeter subsequently creates a seamless connection between interior and garden.

How have the interiors been designed?

Within one volume there are several distinct, inter-connected places accommodating planned and unplanned activities. In contrast to the house’s other rooms, the new space rises volumetrically towards the garden and sunshine while also bringing light inside in different ways. The space is conceived as wood-lined with as much built-in fitting and furniture as possible. The completed space forms the spatial climax of the journey from main entrance, through hall, under main stair landing, to arrive unexpectedly at a new family centre of gravity. The interior is inhabited rather than furnished.

What was the biggest challenge and how did you overcome it?​ 

The physical constraints imposed by the existing, unremarkable (and recently refurbished) rear bathroom extension were the starting point in generating convincing external volumes and an internal spatial sequence. The new mono-pitched roof form helped establish a wide valley gutter/porch canopy which could link to the shallow pitch of this existing extension.

What is your favourite aspect of the project?

The space’s versatility. School homework, sewing, reading, architect’s meetings and family meals have taken place in the booth. The generous window seat hosts individual browsing as well as small and large group conversations. The white wall has prompted digital presentations to professional colleagues. An elderly friend spontaneously laid a prayer rug to pray, and friends from the local mosque hinted at the space’s suitability for events. It is a remarkably inclusive space. The elderly relative whose needs inspired the project sadly died during the construction phase. The clients feel however that the space has restorative and hospitable qualities for everyone – an observation that inspires us.

What was your approach to sustainability?

Longevity is arguably the extension’s most sustainable quality, and determines whether a building might become a suitable repurposable host in the future. The existing villa satisfies this criterion in the way it has been constructed. The latent structural capacity of the existing stone mansion was exploited to minimise the use of new structural elements and concrete foundations. The existing rear stone wall supports most of the new steel structure, which is bolted to it or rests in it to form the skeleton of the new extension. Passive solar gain is achieved by the south and westerly orientation of the main glazing areas. 

Which aspect would you do again next time, and which one wouldn’t you do? 

Using the existing building’s latent structural capacity to minimise new structural elements is always worth exploring. It establishes a special reciprocity with the extension’s warming blanket of insulated fabric to what is, in effect, a typically uninsulated Victorian mansion.

On reflection, draining the generous canopy with a rainwater pipe attached to one of the supporting columns seems rather clunky and, while technically sound, is definitely deserving of an alternative idea, perhaps linked to a landscape feature.

 Christopher Platt is a director at Studio KAP

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