Modular extensions in Edinburgh

Conservation areas come first

A large share of Edinburgh's older housing is inside a conservation area, from the New Town and Stockbridge to Marchmont, the Grange, Morningside and Trinity. Permitted development for extensions does not apply there, so even a small single-storey room needs a planning application, and the council will care about materials and what can be seen from the street or lane.

That does not rule out a factory-built extension. What it changes is the outside: zinc, timber or stone-faced cladding chosen to satisfy planning, fixed to a structure that is still made off site. Settle the appearance with the planners before the factory drawings are frozen.

The houses that suit it

The 1930s bungalows of Corstorphine, Blackhall, Craigentinny and Liberton are the natural candidates, along with post-war semis in Clermiston and the newer estates in South Queensferry and the south-east of the city. Most have a drive, a side gate and a rear wall that is easy to open up.

Tenement flats and the colonies are different. A main-door flat with its own garden can sometimes be extended, with planning permission and the agreement of other owners where ground is shared. An upper flat cannot be extended in any ordinary sense.

Mews lanes and terraces with no side passage are where the method of building matters most. A finished module needs a crane with a clear swing from the road. Flat panels can be carried through a close or a garage, which is why panel systems are the usual answer in the tighter parts of the city.

Councils and paperwork

The City of Edinburgh Council is the planning authority and the building standards verifier inside the city. Musselburgh and Haddington are East Lothian, Dalkeith and Penicuik are Midlothian, Livingston and Linlithgow are West Lothian, each with its own planning and building standards teams.

The council publishes its own guidance for householders on extensions, which is the document planning officers apply. Outside conservation areas the national permitted development limits apply, and whatever the planning position, a building warrant comes before any work on site.

A crane on the street needs permission from the roads team. In controlled parking zones that means suspending bays, which has to be booked and paid for ahead of the lift.

What it costs in Edinburgh

National figures are the honest guide, because nobody publishes reliable ones for Edinburgh alone: finished modules usually land between £2,100 and £3,300 per square metre fitted, VAT included, putting a 20 m² room at about £42,000 to £66,000. Panels usually cost less. In a conservation area, allow more for cladding and for the planning application. The cost calculator does the sum for your own room.