Adding En-Suites and Wet Rooms in Brutalist Flats

Transforming a 1970s Barbican or Golden Lane layout into a high-end luxury apartment inevitably involves the desire for additional bathrooms or modern walk-in wet rooms. However, plumbing in a building constructed entirely from solid, highly reinforced concrete is an exercise in extreme engineering constraint.

Unlike Victorian properties with deep timber floor joists, brutalist flats lack the forgiving underfloor void required to easily run complex new drainage networks.

The Tyranny of the Soil Pipe

The primary barrier to adding bathrooms is waste extraction:

• Proximity to the Service Stack: The original service stacks (the vertical shafts bringing water in and taking waste out) are immovable. Any new toilet, shower, or sink must connect to these stacks with a highly specific 'fall' (the minimum 1:40 gradient required for gravity drainage).
• The Saniflo Compromise: Because you cannot cut deep trenches into the post-tensioned concrete structural slab to achieve this drainage fall, you are often forced to rely on macerator pumps (like Saniflo systems). These allow waste to be pumped upwards and across the flat in smaller, pressurized pipes, but they are noisy and prone to failure, often detracting from a 'luxury' finish.
• Step-Up Wet Rooms: If a gravity drain is essential but the stack is too far, the entire floor level of the new en-suite must be raised on a plinth to create an artificial void beneath the shower trap. The City's LBC usually permits this, provided the new floor structure is acoustically isolated and reversible.

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.

*Published in the Hampstead Renovations Planning Guide Collection — delivering expert design and build strategies for London's most heavily guarded conservation boroughs.*