Do You Need An Architect for Landlords?

The right architect for landlords does not approach a rental property the way they approach a family home. The brief is different, the priorities are different and the measure of a successful outcome is different.

A homeowner wants a space that feels right for their life. A landlord wants a property that lets reliably, commands the best achievable rent, satisfies regulatory requirements and retains its value as an asset. Those objectives are not in conflict with good design, but they do require a design approach that is commercially grounded from the outset rather than aesthetically led.

This guide is written for London landlords, whether you are managing a single buy-to-let, converting a property to an HMO or building a small portfolio. It covers what you should expect from an architect at each stage, the specific planning and regulatory requirements that apply to rental properties and the decisions that have the greatest bearing on yield and long-term asset value. For a broader picture of how we work with investment-focused clients, our developer clients page and commercial clients page set out the range of projects we take on.

Planning Permission and HMO Licensing Are Not the Same Thing

One of the most common and costly misunderstandings among London landlords is treating planning permission and HMO licensing as equivalent processes. They are governed by entirely different sets of legislation, administered by different parts of the local authority and required in different circumstances. An architect for landlords in London needs to understand both and be able to advise clearly on which applies to a specific project.

HMO licensing

A House in Multiple Occupation licence is required from the local authority when a property is occupied by five or more people forming two or more separate households. This is mandatory HMO licensing under the Housing Act 2004. Many London boroughs also operate additional licensing schemes that extend the requirement to smaller HMOs, sometimes down to three or more occupants. The licence is renewed every five years and requires evidence of fire safety compliance, adequate facilities and proper management.

Planning permission for change of use

Converting a property from a single dwelling (use class C3) to an HMO (use class C4) is, in planning terms, a change of use. Under national permitted development rights, conversions to small HMOs of up to six occupants do not require a planning application provided the local authority has not removed those rights. However, London boroughs have been increasingly active in issuing Article 4 directions that remove the permitted development right for C3 to C4 conversions, requiring a formal planning application in areas where HMO concentration is already high or where the council has concerns about housing mix.

Large HMOs of more than six occupants are in use class Sui Generis and always require a full planning application for change of use, regardless of any Article 4 direction. The planning case for a large HMO is assessed on its specific merits, including the impact on housing mix and the character of the area.

Before committing to a conversion project, the planning position should be confirmed with certainty. An architect who has experience of HMO applications across London boroughs, and who understands where Article 4 directions are in force, will identify potential planning barriers at the feasibility stage rather than after design work has begun. Our guide to planning permission in Richmond borough gives a sense of how borough-specific planning policy can affect what is and is not achievable in a particular location.

What Building Regulations Require for HMO Conversions

Planning permission and HMO licensing aside, any significant conversion work requires building regulations approval. For HMO conversions, the building regulations requirements are more demanding than for standard residential refurbishments, and designing to meet them from the outset is considerably more efficient than attempting to retrofit compliance after the design has been fixed.

Fire safety

HMOs are subject to strict fire safety requirements. Fire doors to all habitable rooms and kitchens, protected escape routes, emergency lighting on stairwells and landings, heat detectors in kitchens and interlinked smoke detectors throughout the property are all standard requirements. The specification of fire-rated construction between rooms and floors, and the design of the means of escape, must be addressed in the architectural drawings.

Sound insulation

Walls and floors between lettable rooms in an HMO must achieve specific sound insulation performance values. This typically requires acoustic upgrades to the existing construction, including acoustic mineral wool in partitions, resilient bar systems on ceilings and acoustic floor builds. The specification needs to be confirmed at design stage so that the contractor prices it correctly.

Room sizes

HMO regulations set minimum room sizes for sleeping rooms. For a single adult, the minimum is 6.51 square metres. For two adults sharing, it is 10.22 square metres. Rooms below the minimums cannot be used as sleeping rooms. The room layout of the conversion must be planned against these minimums from the outset, as a design that fails to achieve the minimum sizes in the majority of rooms will not licence correctly regardless of how well it has been built.

Ventilation and thermal performance

Each habitable room requires adequate ventilation. Kitchens and bathrooms require mechanical extraction at specified rates. The thermal performance of the building envelope must meet Part L of the building regulations, which may require upgrading insulation to walls, roofs and floors as part of the conversion works.

Maximising Lettable Area and Rental Yield

The commercially astute landlord approaches an HMO conversion not just as a compliance exercise but as a design opportunity. The configuration of rooms, the provision of en-suite facilities, the quality of shared spaces and the specification of fixtures and fittings all have a direct bearing on the rental yield the property can achieve. Our work with developer clients consistently demonstrates that design-led thinking at the conversion stage produces measurably better rental outcomes than minimum-compliance approaches.

En-suite rooms command a significant rental premium in London, particularly in boroughs where there is strong professional tenant demand. Where the building fabric allows, designing en-suite provisions into the majority of rooms rather than relying on shared bathrooms will increase the achievable rent per room and reduce void periods. An architect who understands this calculus will design the bathroom configuration around the revenue model rather than around the minimum requirements.

Shared spaces also matter more than many landlords appreciate. A well-designed shared kitchen, a utility space that genuinely works for multiple occupants and communal areas that feel considered rather than institutional all contribute to tenant retention, which is the single most direct driver of net yield over time.

Where the existing footprint of a property limits the number of lettable rooms that can be created, extending the building may be the most effective way to increase yield. Our guide to rear extensions in London covers the planning routes for extending a house, and our guide to loft conversions in London is relevant where adding a storey could create additional lettable rooms.

Extending and Improving Existing Rental Properties

Not every landlord instruction involves an HMO conversion. Many London landlords own single-let properties whose rental value and capital value could be improved through a well-considered extension or refurbishment. The same principles that apply to owner-occupied residential extensions apply here, with the additional consideration of the rental market’s response to the improvements. Our article on whether to improve rather than move is relevant to landlords assessing whether an extension programme makes financial sense on a specific property.

For landlords who own period properties in London, the condition of the existing fabric is often the primary constraint on rental value. Poorly insulated properties with ageing services, single-glazed windows and inadequate heating systems will underperform the market regardless of how well the layout has been configured. An architect who takes an honest view of the building’s condition at the outset of a project, and who specifies the fabric upgrades that are genuinely necessary rather than those that are merely desirable, adds direct value to the landlord’s return.

For landlords with multiple properties or a development pipeline, our guide to developing small urban sites in London addresses the specific considerations that apply when a portfolio-building strategy involves new build or change of use projects.

Understanding the Costs Involved

The cost of an architect for landlords in London varies depending on the nature and scale of the project. Our comprehensive guide to architect costs in London sets out the full picture, including typical fees at each RIBA stage, what is and is not included in a standard fee and what additional consultant costs to budget for. For landlord-specific projects, the key additional costs to factor in beyond the architect’s fee are as follows.

Structural engineer

Most HMO conversions involve some structural work, particularly where new partitions are introduced, floor penetrations are created for en-suite drainage or an extension is added. A structural engineer is always required and their fee should be budgeted separately.

Building control

Building regulations approval involves a fee payable to the local authority or an approved inspector. For HMO conversions, the scope of the building regulations submission is broader than for a standard residential project, and the inspection regime during the build is more intensive.

HMO licence fee

The licence fee varies by borough and by the size of the HMO. It is a one-off cost at the point of first licensing and a renewal cost every five years. Some boroughs also charge an inspection fee as part of the licensing process.

What to Look for When Appointing an Architect as a Landlord

The qualities that matter most in an architect for landlords in London are commercial awareness, regulatory competence and local planning knowledge. Design flair matters, particularly for the quality of shared spaces and the specification of finishes, but it is not the primary criterion. You can see examples of the projects we have delivered across residential and commercial sectors in our portfolio and across our full range of services.

Regulatory competence means understanding HMO licensing requirements, building regulations for HMOs and the planning framework for change of use in the specific borough the property sits in. An architect who has completed a significant number of HMO projects across London will have navigated the variation between borough policies and will know where to anticipate problems before they arise.

Commercial awareness means understanding that the project is an investment decision, not a design exercise. The architect should be able to demonstrate, from the outset of a project, how the design choices being recommended will affect the rental yield, the licensing position and the long-term value of the asset.

Talk to Discover Architecture

At Discover Architecture, we work with landlords and property investors across London on HMO conversions, single-let extensions and development projects where commercial thinking and design quality need to work together. We understand that a rental property is a business asset and we approach every project with that in mind. If you would like to discuss a project, get in touch directly or explore our residential, commercial and developer client services to understand the full range of what we offer.

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