From the team behind Hampstead Renovations · Est. 2009 · Learn more
Case StudyHampstead Garden Suburb, NW11June 2025

House Extension, Hampstead Garden Suburb

A single-storey rear extension to an Arts & Crafts semi-detached house in Hampstead Garden Suburb, designed with a traditional clay-tiled pitched roof to satisfy both Barnet LBC planning requirements and Hampstead Garden Suburb Trust design guidelines. The extension created an open-plan kitchen and dining space.

Project Type

Single-Storey Rear Extension

Duration

16 weeks

Project Value

£95,000

The Challenge

Hampstead Garden Suburb Trust will not permit flat-roof extensions to Arts & Crafts properties — a pitched roof with traditional materials is required. A pitched roof extension is structurally and technically more complex than a flat roof and significantly more expensive. The existing rear elevation had an original Arts & Crafts bay window that the clients wanted to retain, requiring the extension to be designed around it.

Our Solution

Our architect designed a pitched-roof extension with matching clay peg tiles, gabled end, and timber details sympathetic to the Arts & Crafts character of the house. The existing bay window was retained as an internal feature, framed by the new extension walls. Both Barnet and Trust consents were obtained in 12 weeks. The traditional construction used lime mortar and timber frame rather than block and mortar.

Results

  • Barnet LBC and HGS Trust dual consent obtained in 12 weeks
  • Pitched clay tile roof — matching existing house materials
  • Original Arts & Crafts bay window retained and reframed
  • 24m² open-plan kitchen-diner created
  • Crittal-profile glazing to gable end — Trust-approved
  • Underfloor heating throughout extension
  • Estimated property value uplift: £160,000

Key Features

  • HGS Trust-approved pitched clay tile roof
  • Timber frame construction — lime mortar and traditional materials
  • Existing Arts & Crafts bay window retained as internal feature
  • Crittall-profile gable end glazing
  • Underfloor heating — wet system
  • Bespoke kitchen with Shaker cabinets and quartz worktops

Specification

ItemSpecification
Roof structureCut roof timber frame, C24, Keymer clay peg tiles to match existing, lime mortar bedding
External wallsTimber frame with brick-slip cladding, matching existing roughcast render to upper section
Gable glazingCrittall Homelight W20 gable glazing, RAL 9005, fixed and opening lights, double-glazed
KitchenBespoke in-frame Shaker kitchen, Silestone Eternal Calacatta, Bosch integrated appliances
UFHWarmup Clypso wet system, 75mm screed, manifold zone controlled from kitchen
FlooringEngineered oak wide board, character grade, UV oiled, throughout extension

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