The Georgian townhouse

Load-bearing brick, timber lintels, and a plan that is part of the listing

Solid brickwork in lime mortar, often with a fine gauged front elevation and much rougher stock brick behind. Timber lintels over openings, sometimes decayed. Floors of wide softwood boards on joists notched into the party walls. Roofs behind parapets, frequently with a lead-lined valley or butterfly arrangement that has been patched many times. Vaults under the pavement in front, and a lightwell and area at basement level.

The staircase, the cornices, the panelled shutters, the architraves and the door furniture are usually the reason the building is listed. So, often, is the sequence of rooms. A layout change that reads as obvious on a drawing may be the single thing a conservation officer will not accept.

Servicing, basements and rear additions — carefully

Bringing a Georgian house up to a modern standard of comfort is generally achievable: discreet MVHR, secondary glazing or slim-profile double glazing where consented, underfloor heating in the basement and lower ground, a fully renewed electrical and plumbing installation routed to avoid cutting historic fabric, and lighting designed to work with the plaster rather than through it.

Basement deepening and rear additions are common and are frequently consented, but the engineering is substantial: underpinning in sequence, temporary works throughout, and a waterproofing design that has to work against a building nobody wants to see move.

Consents, and the cost of getting it wrong

Unauthorised works to a listed building are a criminal offence, and enforcement can require reinstatement. That changes how a contractor should behave on site. Where something is found that is not on the drawings — a beam that has to move, a wall that turns out to be historic — the correct response is to stop and refer it to the design team and the local authority, not to make a decision and report it afterwards.

Access and logistics are the second risk. Central London townhouses rarely have storage, often have controlled parking and restricted delivery hours, and are usually surrounded by occupied neighbours. On a constrained square, materials are called off against the programme rather than stockpiled, and waste leaves site continuously.

The third is the interface between old and new. Junctions between retained lime-built fabric and new cement-based or reinforced elements are where damp, cracking and failure concentrate, and they need detailing rather than filling.

What is ours, and what is not

Eternal carries out the construction works. Heritage and conservation matters, listed building applications, structural design, temporary works design and waterproofing design are by the appointed consultants for the project. Chartered status describes professional standing and competence in construction management; it is not an approval of any project, and it is not a substitute for the specialist designs a building of this kind requires.

What we do bring is the site discipline these houses need: recorded condition surveys, protection of retained fabric before anything is opened up, sequencing agreed in advance, and a habit of raising anything that appears to depart from the consent rather than proceeding and asking later.

Knightsbridge · Chelsea · Belgravia · Mayfair · Marylebone · Islington

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