How to build a roof terrace

As well as providing valuable outdoor space, roof gardens can reduce energy bills, cut noise pollution and provide a haven for wildlife

  • Does your roof have the potential to be a terrace?

    Lisa Andrews of Urban Roof Gardens offers this advice: ‘A terrace is potentially viable if you have an existing outside space that can be reinforced to be load-bearing, a window that can be changed for a door and new access can be created.’

    What if your roof isn’t flat?

    A flat roof will be cheaper and easier to work with, but even if your roof is pitched there are options. An external wall can be built up to create a flat surface or you could get an ‘inverted dormer’ – that’s where they chop a chunk out of the roof.

    How big will it be?

    According to Andrews, ‘the amount of space often depends on privacy issues [such as a terrace overlooking a neighbour’s property]. If so, the boundary line is often brought back. Screening is also often suggested in the form of opaque-glass panels.’ And the hatch or stairs on to the roof will eat up some of the space.

    How much will it cost?

    A basic roof terrace may cost upwards of £7,500, but it’s possible to spend up to £45,000. Andrews reckons in the long term it will pay for itself, if not make you a profit; properties with a roof terrace are are worth between 10 and 25 per cent more after the work is done. Remember to save some of the budget for furniture and accessories.

    Before you start…

    Find out from your architect whether you will need planning permission, then contact the local planning authority to make an application. Even if what you’re planning doesn’t require permission, always tell your neighbours what you are intending to do – it’s a goodwill gesture that will make them less likely to complain. Companies such as Urban Roof Gardens offer a full service, from design and construction to planting. The other option is to contact an architect who can take care of the planning permission and hiring builders. Try and use someone who has successfully worked in the area as they will have already dealt with the local council. The RIBA ( offers a client advisory service to help you find someone suitable.

    Now accessorise

    Andrews says: ‘Great fun can be had with the addition of illuminated lightweight outsize planters and shade sails for ultrasunny terraces. There is a wide choice of fire pits which will warm you as the daytime temperatures fall and grill your supperat the same time.’ The main things to think about are:
    Go for plastic pots and mix normal compost with a product such as perlite or hydroleca to minimise the weight on the roof while still retaining water well. These are available from all good garden centres. Bear in mind the aspect of the terrace – sheltered terraces can have some success with Mediterranean plants such as olives and even oranges; for windy, exposed terraces, grasses and bamboo cope well.
    Go for lightweight pieces that are easy to maintain and if they’re flatpack, assemble them on the terrace.
    This is the key to creating atmosphere after dark and should be thought about during the design process. A couple of waterproof power sockets might be useful for additional appliances. Circuit breakers and lighting specifically designed for the outdoors will prevent any shocks.

    Useful contacts

    Anderson, Wilde & Harris (Architects)
    75 Kenton St, WC1 (0800 071 5517/

    Online company with a great selection of fire pits, planters and garden shades. (02392 410045/

    Husband & Carpenter Architects
    13b St George Wharf, SW8 (020 7793 3660/

    MK Architects
    22 Dollis Park, N3 (020 8349 3202/

    Stunning landscaping for existing roof gardens and terraces. 24 Camden Mews, NW1 (020 7485 6464/

    Online garden furniture. (0116 270 8100/

    Petersham Nurseries
    Garden furniture, plants and accessories. Off Petersham Rd, Richmond, TW10 (020 8940 5230/

    Pod Flowers
    Unusual plants, flowers and horticultural design. 60 Exmouth St, EC1 (020 7837 8111/

    ‘Roof Gardens, Balconies and Terraces’ by David Stevens and Jerry Harpur
    An inspiring yet practical guide. Published by Mitchell Beazley at £14.99 (available from

    Urban Roof Gardens
    42 The Grove, W5 (0800 652 8848/

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