HMO Conversions · London

HMO Conversion
Architects London

Turning houses into high-yield HMOs takes more than a floor plan and a building notice. It takes someone who understands the planning system, knows how to design rooms that actually let well, and can manage the build without the project dragging on for months. That is what we do.

Talk to Us About Your Project
HMO conversion architects London - double storey rear extension and conversion by Rosace Studio

What We Do

Architecture, planning and construction for HMO conversions

Most developers we work with have a similar story. They have bought a property, or they are about to, and they want to convert it into a 5, 6 or 7-bed HMO. They have spoken to a few architects and builders but nobody seems to handle the whole thing - the design, the planning application, the building regs, the actual build.

We do all of it under one roof. Rosace is an architecture and construction studio, so you are not coordinating between three or four different companies. You brief us once and we take it from there.

We work with developers and landlords across London who are converting properties from C3 residential use into C4 or sui generis HMOs. That means we deal with Article 4 Directions regularly, and we know what planning officers in each borough are looking for.

  • C3 to C4 conversions (small HMOs, up to 6 people)
  • Sui generis HMO applications (7+ occupants)
  • Article 4 Direction planning applications
  • HMO extensions - rear, loft and side return
  • Full interior layouts optimised for rental yield
  • Building regulations and fire safety compliance

Why Developers Choose Us

One team from planning to handover

The biggest headache in HMO development is coordination. The architect draws something up, then the builder says it cannot be done for the budget, and the planning consultant disagrees with both of them. Meanwhile the mortgage is ticking.

Because we handle architecture, planning and construction in-house, these problems do not arise. Our architects design with buildability and cost in mind from day one. Our construction team prices the job before we submit the planning application, so you know what you are committing to.

We also design interiors that tenants actually want to live in. Good room proportions, decent natural light, proper storage, shared spaces that work. The result is fewer voids, better tenants and stronger yields.

We cover all of Greater London and a 30-mile radius including Surrey, Hertfordshire, Essex, Kent and Buckinghamshire.

How It Works

From acquisition to tenants

01

Feasibility

You show us the property - or the listing if you have not bought yet. We assess the planning position, check for Article 4 restrictions, and tell you honestly whether the numbers work.

02

Design

We draw up the layouts, including any extensions. Every room is sized to meet HMO standards, with en-suites and communal areas that actually function day to day.

03

Planning

We prepare and submit the planning application - whether that is an Article 4 submission, a sui generis application or a lawful development certificate. We handle all council correspondence.

04

Build

Our in-house construction team delivers the conversion. Building regs, fire safety, sound insulation - it is all managed under one contract, with one project manager and no finger-pointing.

Related Projects

Extensions and conversions across London

Double storey rear extension in Kingston - HMO conversion project
Hackney terrace house rear extension
Semi-detached kitchen extension in Kensington
View all projects

Common Questions

HMO conversions in London - answered

Do I need planning permission to convert a house into an HMO in London? +
It depends on the borough. In areas covered by an Article 4 Direction, you need full planning permission to convert from a C3 dwelling to a C4 HMO (3-6 occupants). For a large HMO with 7 or more occupants (sui generis use), planning permission is always required. Most inner London boroughs now have Article 4 Directions in place, so it is worth checking before you buy.
What is an Article 4 Direction and how does it affect HMO conversions? +
An Article 4 Direction removes the permitted development right that would normally allow a house (C3 use class) to be converted into a small HMO (C4 use class) without planning permission. In boroughs with an Article 4, you must submit a full planning application. Rosace prepares and manages Article 4 HMO applications regularly across London.
How much does an HMO conversion cost in London? +
Construction costs for HMO conversions in London typically range from £1,500 to £2,500 per square metre, depending on the scope of work. A full conversion of a 3-bed terraced house into a 6-bed HMO might cost between £80,000 and £150,000 including an extension. Architectural and planning fees sit on top, usually between £8,000 and £20,000 depending on the complexity.
Can I extend the property as part of an HMO conversion? +
Yes, and most developers do. A rear extension, loft conversion or both will add bedrooms and significantly improve rental yield. Rosace handles both the extension design and the HMO conversion as one coordinated project, which means a single planning application and one point of contact throughout.
What areas of London does Rosace cover for HMO projects? +
We work across all of Greater London and within a 30-mile radius, including Surrey, Hertfordshire, Essex, Kent and Buckinghamshire. We have completed HMO and extension projects in boroughs including Wandsworth, Hackney, Islington, Camden, Lewisham, Southwark and Lambeth.

Start Your Project

Got a property in mind?

Send us the listing or the address and we will give you an honest assessment - what is achievable, what the planning position looks like, and roughly what it will cost. No obligation.

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