Renovating a London townhouse, what the work involves

A London townhouse is a difficult building to renovate well. It is tall and narrow, it has been altered before, and much of what makes it worth owning is protected. Here is what the work actually involves, and where it usually goes wrong.

The plan is the problem, not the floor area

Most of these houses were built with a service stair, small cellular rooms and a kitchen in the basement. Families do not live like that any more. The work is usually about circulation and daylight rather than square footage: where the stair lands, how the back of the house opens to the garden, and whether the middle of the plan gets any light at all.

Heritage detail has to be recorded before it is touched

Cornices, architraves, shutters, chimneypieces and the original joinery are what a buyer is paying for. Photograph and measure them before strip out, because they are easy to lose and expensive to reinstate. Where something has to come out, take a mould.

The services are the hidden project

A period townhouse will usually have undersized electrical capacity, old pipework, poor drainage falls and no ventilation strategy. Modern heating, cooling, lighting control and data all need space in floors, ceilings and risers that the original building never allowed for. Settle the MEP design before the finishes are chosen, or you will lose ceiling height to it later.

Structure and neighbours

Removing a spine wall, lowering a lower ground floor or building a rear extension all engage the structure and usually the Party Wall etc. Act. Start the notices early, because the programme is built around them rather than the other way round.

Sustainability, without changing the elevation

Insulation, airtightness and glazing performance all have to improve without altering what the street sees. That is a design problem rather than a shopping list, and it is the part of a conservation-area renovation that takes the most thought.

Completed examples

See the Chelsea townhouse, the townhouse basement and extension and the Knightsbridge townhouse for finished work, or look through the whole portfolio.

If you own a London townhouse and are working out what to do with it, tell us about it.