House
extensions
in Marylebone, W1U
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Hampstead Chartered Surveyors & Building ConsultancyMarylebone's plots are narrow and fixed, and behind the houses the Harley Street audit records mews buildings of about two storeys that match their plot widths. An extension here weighs the back of the house against the mews behind it.
Marylebone is one of London's most complete Georgian quarters, and extending here means working with its great estates as well as the council. The area lies in the City of Westminster, much of it inside the Marylebone Conservation Area and on the Portman and Howard de Walden estates. The Harley Street Conservation Area, first designated in 1968 around Portland Place, Harley Street and Wimpole Street, covers the Howard de Walden grid, while the Portman Estate Conservation Area takes in the late-18th and early-19th-century streets nearby.
There is also a view to respect. The strategic vista from Primrose Hill to the Palace of Westminster crosses the conservation area from Park Crescent to Oxford Street, so roof and upper-storey proposals are assessed for visibility as well as design; the Marylebone Village Area of Special Archaeological Priority sits largely within the Harley Street area. Montagu Square and Bryanston Square carry elegant Portman Estate terraces, restored with authentic joinery and plaster.
Cost follows consent on the estate-held grid, where strategy and coordination lead. A Marylebone rear extension or side return is priced after a feasibility visit.
Adding space to a Marylebone house
Westminster's summary of the Harley Street Conservation Area describes a Georgian core of townhouses of a similar scale on consistent, narrow plot widths, and the 2004 mini guide notes that the main roads hold large houses and the side streets smaller ones. The width of the plot is fixed, so extra space comes from the back, the roof or the mews.
The 2008 audit records that the area was built by a number of speculative builders over several years, and that later alterations have left few stretches of completely uniform terrace. Before proposing an addition we look at the backs of the neighbouring houses to see what that row already has.
Mews properties in the area, according to the audit, are generally two storeys, relate to the plot width of the main house they served, and were built in brick, simply and robustly detailed, most with timber carriage doors below and smaller openings, usually sashes, above. Extending a mews house keeps that two-part front.
The audit counts poorly located plant among the area's negative features, most often found on the backs of buildings in mews, alleys and on roofs, and warns that even wires, pipework and flues can harm a building and the street. An extension here is drawn with its services routed inside.
In the Portman Estate area the houses are generally stock brick with modest stucco dressings, and an addition there is built in matching stock brick. Where the property is held on a Portman Estate lease, the estate's licence fee depends on the nature, extent and cost of the alterations, so the licence is prepared alongside the planning drawings.
Westminster allows no noisy building work on Sundays or bank holidays, and on other days limits it to 8am to 6pm on weekdays and until 1pm on Saturdays. Deliveries to a rear addition are agreed with the neighbours in the mews behind.
A related project, not in Marylebone, is Fitzjohns Avenue, NW3: a new basement and a rear extension at a house in NW3.
The first design meeting sets out the three routes to more space, rear, roof or mews, and tests each against the listing, the neighbours' daylight and the client's budget before one is drawn in detail.
Sources: Westminster City Council: Westminster's conservation areas, character summaries and overview; Westminster City Council: Harley Street conservation area mini guide (May 2004); Westminster City Council: Harley Street conservation area audit (SPD, adopted 16 June 2008); Westminster City Council: Portman Estate conservation area mini guide (May 2004); The Portman Estate: licence to alter, frequently asked questions; Westminster City Council: noise problems we can investigate.
House Extensions in Marylebone: Questions
How do the Marylebone estates and conservation areas affect an extension?
Marylebone lies in the City of Westminster, much of it inside the Marylebone Conservation Area and on the Portman and Howard de Walden estates. The Harley Street Conservation Area covers the Howard de Walden grid around Portland Place, Harley Street and Wimpole Street, so a Marylebone extension is shaped by both the conservation area and the estate.
Is there a protected view that affects roof work in Marylebone?
Yes. The strategic view from Primrose Hill to the Palace of Westminster crosses the conservation area from Park Crescent to Oxford Street, and the Marylebone Village Area of Special Archaeological Priority lies largely within the Harley Street Conservation Area around Marylebone High Street. Roof and upper-storey proposals are tested against that protected vista.
What does an extension cost in Marylebone?
A Marylebone rear extension, side return or wraparound is priced after a feasibility visit. On the estate-held grid, the consent strategy and estate coordination usually lead the figure, so we set those first.
Which Marylebone streets have the elegant houses suited to extending?
Montagu Square and Bryanston Square carry elegant Portman Estate brick terraces, Dorset Square adds a leafy Regency set-piece, and Marylebone High Street anchors the mansion flats and conversions above the shops. Those Georgian townhouses are restored with authentic joinery and plaster detail.
What is the property stock like in Marylebone?
Marylebone is one of London's most complete Georgian quarters: Georgian townhouses, Portman Estate terraces and mansion flats. Its characteristic streets include Montagu Square, Bryanston Square, Dorset Square and Marylebone High Street, and leading with the consent strategy keeps a Marylebone scheme on track.
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