Sui Generis & Article 4 HMO Planning Specialists — UK Wide
How We Can Help
We're RIBA Chartered Architects specialising in complex HMO planning applications, including Sui Generis large HMOs and HMOs in Article 4 areas where permitted development rights to convert a single dwelling (C3) into a small HMO (C4) have been removed.
We go beyond the architectural design. As your Planning Agent, we can prepare the full planning application, submit it, and monitor it right through to decision managing the entire process under one roof.
With over 8 years working exclusively on property investor and HMO projects, we've built deep experience navigating these often more contentious applications, which typically face more council scrutiny and more objections than standard planning applications.
We work across all scales, from small 4 or 5-bed HMOs to our largest HMO project to date being a 36 bed commercial to HMO conversion.
613+
HMO bedrooms & counting since 2017
136+
New residential
dwellings since 2017
48+
Councils submitted planning applications in
96%
Planning Application Success Rate
Our Process
Research — Local planning policy and Article 4/Sui Generis constraint checks before any design work starts.
Design — We design space maximising layouts that meet local HMO amenity standards and respond to local planning policy concerns.
Submit — We prepare and submit the full application, including all required drawings and collate the supporting third party statements.
Monitor — We proactively track every application through the system rather than waiting for the council to come back to us.
Liaise — We stay in regular contact with your planning officer throughout, addressing questions or concerns as soon as they arise.
Resolve — If issues come up mid-application, we respond swiftly with revisions rather than letting momentum stall.
Why Work with Portfolio Architects?
We work exclusively with property investors and landowners, so our designs are shaped around returns and deliverability.
Our background as property investors ourselves means we bring more than an architectural lens, we understand your numbers and risk, not just your floor plan.
RIBA Chartered Architectural Team with 10+ years experience.
96% planning application success rate across 48+ UK councils over 8+ years.
613+ HMO bedrooms and 136+ new dwellings delivered since 2017.
Fixed-fee pricing, agreed upfront so no surprises.
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A Sui Generis HMO is a large house in multiple occupation with 7 or more unrelated occupants. Standard small HMOs (3–6 occupants, more than one household) fall under Class C4 and can sometimes be permitted development. Sui Generis HMOs always require full planning permission, face heavier scrutiny, and typically attract more objections so the strength of the planning case matters more than usual.
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Yes. An Article 4 Direction removes permitted development rights for HMO conversions in that area, meaning any change of use from a C3 single family dwelling to an HMO (regardless of size) requires a full planning application. We check your property against the local authority's Article 4 designation as the first step of any project.
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Our overall planning application success rate is 96% across 48+ councils over 8+ years. Sui Generis and Article 4 applications are more heavily scrutinised by nature, which is why planning strategy not just design is built into our process from the outset.
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We review the reasons for refusal and advise on the best path forward a revised resubmission or an appeal. We've turned previous refusals (by other Architects / designers) into approvals by redesigning schemes from the ground up.
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Yes. We agree a fixed fee upfront before any work begins, so there are no surprises partway through the project.
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Most applications are determined within 8 weeks, though Sui Generis and Article 4 cases can take longer due to added scrutiny and, in some cases, committee referral. We factor realistic timescales into your project planning from day one.
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Yes. For particularly complex or politically sensitive sites, we're happy to work alongside a Planning Consultant to strengthen the application. But unlike many architectural practices, we've built up significant in-house experience submitting planning applications without a separate planning consultant advocating for the proposal ourselves, as your planning agent.
Frequently Asked Questions