At the apex of the Barbican terrace blocks lie the iconic, double-height penthouses, distinguished by their dramatic, semicircular barrel-vaulted roofs clad in copper or zinc. These are some of the most sought-after residential spaces in the City of London, but altering them is exceptionally difficult.
The penthouses represent the crowning architectural gesture of the estate, and the City Corporation is uncompromising in its defense of their spatial volume and external silhouette.
Protecting the Double-Height Void
The primary conflict in penthouse refurbishment revolves around maximizing floor area:
- Mezzanine Insertions: The vast volume under the barrel vault often tempts owners to insert a new mezzanine floor to create an extra bedroom or study. LBC assessments aggressively resist this. The original architects intended the double-height space to be experienced as a singular, open void. Inserting a solid mezzanine interrupts the geometry and the expansive glazing.
- The 'Floating' Compromise: If a mezzanine is ever permitted, it must be demonstrably 'reversible' and visually disconnected from the glazed walls. It must float—constructed using lightweight steel or glass—and cannot touch the barrel vault itself, thereby preserving the original spatial read of the apartment.
- Skylights and Roof Apertures: The copper/zinc barrel roofs are totally sacrosanct. Attempting to punch new conservation rooflights into the curve of the vault to illuminate a new upper gallery will be dismissed instantly as severe harm to the Barbican's recognizable skyline.
How We Can Help
If you are considering a major refurbishment, amalgamation or penthouse extension in the City of London, our in-house architectural and construction teams are highly experienced with the specific constraints and policies of this council. Do not leave your planning application to chance—our Planning & Permissions and Architecture services are explicitly designed to handle strict London authorities from initial conceptual design through to final, legal consent.
Once permission is secured, our Refurbishment & Interiors division carefully manages the execution, guaranteeing the design integrity is maintained throughout the build phase.
Official City of London Corporation Resource
Verify the latest planning policies, application fees, and validation requirements directly via the official council portal.
Visit City of London Corporation Planning Portal →*Published in the Hampstead Renovations Planning Guide Collection — delivering expert design and build strategies for London's most heavily guarded conservation boroughs.*