Best One-off House/Extension

House extensions don’t get much more innovative – or challenging – than this. To convert the dilapidated grade II-listed Lymm Water Tower in Cheshire into a family home, a wraparound extension was added and the tower itself completely renovated. It took five years of design and planning, all carried out with the close involvement of the building control team, before the project was finally right – but all involved agree that it was worth the effort. The sensitive contemporary design of the extension blends with the building’s traditional features and the new spaces have been arranged to make the most of the changing quality of natural light – the sun rises on the kitchen and sets on the dining area. And of course then there’s the all-important hot tub on the roof deck …

The finalists

Bath and North-east Somerset council: Yellowstones, Bath

This magnificent, imposing detached house is all about luxury – on the surface. As one would expect from the name, the soft, yellow stone walls envelope a large family home on a dramatic slope, with a huge roof terrace just crying out for parties. The truth, though, is that this was a tricky build, with contractor Richard Wells having to build retaining structures during the groundworks to counter the steepness of the site. And it is a thoughtful build, too, with many materials including those yellow stones, being locally sourced.

Elliott Edward Construction: 2 Monkhams Avenue, Woodford Green, Essex

This is a refurbishment and extension project with a difference. Working closely with the council to ensure that this conservation-area property remained in keeping with the other houses, Edward Elliot restored all the original features of this enormous detached Edwardian townhouse. This involved copying all the windows, doors and external details to exact requirements, sourcing what it could from local firms, and retaining the original elements where possible. The property was also extended to include a luxurious conservatory.

Kentmere Homes: Wealden Hall, Wrotham, Kent

What looks like a truly spectacular barn conversion is in fact an equally spectacular new-build. With tythe-barn proportions, the most striking feature of Wealden Hall is its magnificent two-storey, entirely glazed central area. This has stairs up to a loft-style hallway suspended in the centre, flanked by the double-height main living spaces, and from which the other upstairs rooms can be reached. it is, in short, a superb architectural antidote to the usual housetype, and one that creates a soaring sense of space.

Vale of Glamorgan council: Llanmihangel Barn, Cowbridge, Wales

This project really is a barn conversion – and what a barn conversion it is. The original oak roof structure has been maintained throughout and forms an integral part of the reception rooms. But it’s not all rustic, though, as this home’s occupants will also enjoy such luxuries as underfloor heating, central multifuel stove with a flue that reaches up to the ceiling, integral vacuuming system and a top-of-the-range kitchen.

Wychavon council: Sunnyside, Pebworth, Worcestershire

Sunnyside is a charming thatched cottage-style home that is in reality a large family home. This extension was built using old techniques and carried out with superb skill. Despite its size, all the details and proportions of the cottage are there, from inglenook fireplace to deep-pitch roof thatch, and from immaculately placed dormer windows to well-specified doors.

A delight.