Start a project ↗FREQUENTLY ASKED QUESTIONS
Planning, costs, timescales and the rules that catch people out — answered plainly. If your question is not here, call us on 0203 151 1224.
It depends on the work and your address. Many extensions and loft conversions fall within permitted development, but flats, maisonettes, conservation areas, Article 4 directions and listed buildings have tighter rules or no rights at all. We confirm the position for your specific property before design begins.
Single-storey extensions typically run from £2,200 to £3,300 per square metre depending on specification and structure. Double-storey extensions cost less per square metre of floor added. We design to a target budget from the outset.
Most London loft conversions fall between £45,000 and £90,000, with mansard and L-shaped dormer schemes at the higher end. Rooflight-only conversions cost less. Head height, structure and stairs are the big variables.
Householder and minor applications carry an eight-week statutory target from validation; major schemes are thirteen. Validation itself can add weeks if documents are missing, which is why we prepare the complete drawing set and statements up front.
Permitted development rights allow certain building work without a planning application, within set limits on size, height, position and materials. A lawful development certificate gives you written proof the work is lawful — valuable when you sell.
A direction made by a council that removes specific permitted development rights in an area — commonly used for HMO conversions and in conservation areas. Where one applies, work that would elsewhere be permitted needs a full planning application.
If your building is listed, consent is needed for works that affect its character — inside and out, including many internal alterations. Like-for-like repair usually does not. Unauthorised works to a listed building are a criminal offence, so always check first.
Usually when you cut into or alter a shared wall, build up to the boundary, or excavate within three metres of a neighbour's structure below its foundations — and six metres in some deeper cases. Loft conversions, rear extensions and basements almost always qualify.
If you are removing a load-bearing wall, forming a large opening, extending, converting a loft or adding weight to the structure, building control will expect structural calculations. Our engineers handle this in-house alongside the design.
Planning permission concerns what you are allowed to build and how it looks; building regulations concern how it is built — structure, fire safety, insulation, drainage and ventilation. Most projects need both, and they are separate processes.
A straightforward extension usually runs four to six months through design and planning, then three to five months on site. Lofts are similar; new builds and flat conversions take longer. We give you a realistic programme at feasibility stage.
All 33 London boroughs, including Tower Hamlets, Hackney, Islington, Camden, Westminster, Barnet, Enfield, Haringey, Newham, Waltham Forest, Southwark, Lambeth, Wandsworth, Ealing, Brent and Croydon.
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