HMO Conversions in London: A Step‑by‑Step Guide with Tips and Tricks

kyle6839
1 day ago
4 min read

Who this guide is for

Property developers and landlords new to House in Multiple Occupation (HMO) conversions in London, looking for a practical, no‑nonsense walkthrough from first call to licence sign‑off.

At a glance: what is an HMO?

An HMO is a property occupied by three or more people from two or more households who share facilities (kitchen, bathroom, WC). In London, many boroughs require planning permission for HMO use (even for small HMOs) and all larger HMOs (6+ occupants) require a mandatory HMO licence. Most boroughs also operate additional licensing for smaller HMOs. Always check your borough’s current requirements early.

Tip: Article 4 Directions remove certain permitted development rights in many London boroughs. This often means you do need planning permission to change a dwelling (C3) to an HMO (C4 or Sui Generis), regardless of size.

How Excela Architecture London helps (end‑to‑end)

Feasibility & Strategy: Site visit, measured survey, compliance and planning risk check (Article 4, local HMO standards, amenity & parking).
Concept & Design: Space planning, room count optimisation, daylighting, fire strategy coordination, acoustic approach, refuse & cycle storage layouts.
Planning Services: Pre‑app strategy, full planning/Change of Use applications, design & access statements, management plans, transport/parking notes.
Building Regulations: Detailed technical drawings, specifications, fire door schedules, means of escape, thermal & acoustic performance.
Tender & Contractor Selection: Tender package, scope of works, contractor interviews, value engineering.
Contract Administration (CA): JCT contract setup, progress meetings, valuations, variations, programme monitoring.
HMO Licence Pack: As‑built plans, fire alarm & emergency lighting certificates, amenity schedule, management plan, landlord fit‑out checklist.
Post‑completion: Snagging, sign‑offs, licence submission support.

Step‑by‑step: from first call to keys‑in‑hand

1) Appoint Excela Architecture London

Kick‑off call to capture objectives (target room numbers, rental model, budget, timeframe).
Order measured survey and existing drawings.
Early feasibility against local planning/HMO standards and Article 4.

Deliverables: Fee proposal & programme, survey brief, risk register.

2) Concept design & compliance strategy

Draft concept layouts (ensuite vs shared bath mix, communal space sizing, kitchen spec, refuse/cycle provision).
Fire & compliance strategy outline (compartmentation, fire doors, detection, AOV/escape windows, emergency lighting, protected routes).
Early services strategy (MEP rough‑in, ventilation, extract rates; hot water/boiler or heat pump sizing concept).
Developer review and value‑engineering options.

Deliverables: Concept drawings, outline spec, planning risk note.

3) Planning: change of use & design quality

Confirm use class (C4 up to 6 occupants; Sui Generis for 7+ or where local policy requires).
Prepare planning pack: Proposed drawings, Design & Access Statement, Management Plan, Refuse/Cycle Plan, Parking/Transport Note where relevant.
Submit planning application (or pre‑app where strategy benefits).
Manage borough queries and conditions.

Deliverables: Validated planning application, consultee responses tracked.

4) Technical design & Building Regulations

Detailed plans/sections/elevations; fire door schedule, smoke/heat detection layout, emergency lighting, FD30/FD60 strategy, intumescent details as needed.
Structural design coordination (openings, floor strengthening, loft/stair mods).
MEP coordination (ventilation rates, extract positions, sound attenuation, SVPs, consumer unit locations).
Thermal upgrades (insulation, cold‑bridge treatment, Part L compliance where triggered).

Deliverables: Building Regs drawing pack & specification for tender/control submission.

5) Procurement & contractor appointment

Issue tender pack; run competitive tender or negotiate with trusted contractors.
Clarify inclusions/exclusions; fix programme and payment schedule.
Select contract form (commonly JCT Minor Works or Intermediate depending on scope).

Deliverables: Tender analysis, recommendation report, signed building contract.

6) Construction & contract administration

Pre‑start meeting: site rules, sequencing, temporary works, fire safety during construction.
Regular progress meetings and valuations; manage RFIs and variations.
Quality checks: compartmentation, door sets, closers, seals, signage, acoustic insulation, ventilation commissioning.

Deliverables: Site reports, change control log, certification tracker.

7) Completion, sign‑offs & HMO licence

Collate as‑built drawings, fire alarm commissioning, emergency lighting test, gas safety, EICR, PAT where applicable.
Final snagging and defects list; obtain completion/Building Control sign‑off (where applicable).
Prepare and submit HMO licence application with all supporting documents.

Deliverables: Handover pack, HMO licence submission, borough queries addressed.

London‑specific design & compliance pointers

Article 4: Check early—this often removes automatic C3→C4 permitted development rights.
Room sizing & amenities: Each borough publishes minimum room and amenity standards (kitchens, dining, bathrooms). Design to exceed the strictest likely requirement.
Refuse & cycling: Provide compliant storage with step‑free access; follow borough‑specific waste guidance.
Noise: Party‑wall and internal acoustic upgrades (e.g., resilient bars, acoustic mineral wool, flanking control) are key for tenant comfort and neighbour relations.
Fire strategy: Protected stair, 30/60‑minute compartmentation where needed, FD30S doors, L2/L3 fire alarm (project‑specific), emergency lighting in escape routes—coordinate with a competent fire engineer.
Services capacity: Verify incoming power, water and gas capacities early; multi‑occupancy hot‑water demand can be significant.

Common pitfalls (and how we avoid them)

Under‑sized communal space → Early space‑standards check & test‑fit options.
Over‑optimistic room count → Financial model vs policy‑compliant layouts, then value‑engineer.
Late fire/MEP coordination → Freeze compliance strategy at concept stage and carry through to technical.
Ignoring Article 4 → Planning check before offers/exchange where possible.
Poor refuse/cycle solutions → Integrate early to avoid refusals or licence conditions.

To‑Do List for First‑Time HMO Developers

Before purchase / early due diligence

Pre‑planning

Planning

Technical design & tender

Construction

Handover & licensing

FAQs

Do I always need planning permission for an HMO in London?

Often, yes—especially where an Article 4 Direction is in place. We’ll check and advise per borough.

What’s the difference between C4 and Sui Generis?

C4 usually covers small HMOs (up to 6 residents). Larger or intensively managed HMOs are typically Sui Generis.

How long does licensing take?

Varies by borough. We prepare a complete application to minimise back‑and‑forth.

Ready to talk?

Excela Architecture London can take your HMO from feasibility to licence.

Let’s discuss your site and targets: layouts that rent well, compliant design, and efficient delivery.