Insider insight
How to ensure a successful extension
PLANNING PERMISSION Make sure to allow time and energy for managing the planning permission process. ‘[It] was challenging,’ admits architect Will Gamble, talking about his Parchment Works project. ‘It involved lots of back and forth and detailed discussion with the local planning authority due to the sensitive nature of the listed building and scheduled monument but we finally arrived at a design that everyone was happy with.’
MANAGING THE BUDGET ‘Cost control starts from the outset, says architect Andrew Mulroy: ‘Try to keep as much of the existing structure as you can. This means that all areas of the house are fully utilised rather than some rooms being dark and redundant. Get regular cost checks on your design as it evolves so you can steer it back on track before going out to tender. This will allow you to understand where financial risks are and help avoid the temptation to change things on site, which is always more expensive.’
THINKING ABOUT THE PLANET
By their nature extensions are not built in isolation. The design must consider the building they are connected to and also the environmental impact. ‘One of the key decisions for our Samarkand project was, should we knock down and start again, or work with what we have?’ said Steven Clarke from Napier Clarke Architects. ‘We believed we could work with the original house as a way of creating a highly sustainable project through the virtue of retaining the existing.’
Steven’s clients were keen to retain the existing structure if it was more cost effective, but they also recognised the sustainable benefits. Once the decision was made, the ground floor, first floor and roof were insulated to reduce thermal loss. All windows and doors were changed from single-glazed to doubleglazed and the heating system was replaced.
LETTING LIGHT IN Light is a vital consideration for extensions – and glazed doors, windows and skylights can be game-changers. Spencer Guy at architecture and design studio Levitate illustrates how important it is to know where light is coming from and how it will change through the seasons: ‘Our client’s brief was for the space to be used comfortably during the day in summer and in the evening in winter. The analysis showed a glazed roof would work fine in summer through the use of shading devices but it was a challenge in winter without excessive heating. We redesigned the roof to include the characteristics of a conservatory but using smaller roof lights so more of the fabric could be insulated. The roof lights were still large, but they were standard products with proprietary opening systems, which made for a better functioning, more cost-effective solution.’