The HMO Market: Size, Trends and Risks

Introduction

Houses in multiple occupation (HMOs) are multi-tenant homes where three or more unrelated households share common facilities. For investors, the attraction is clear: multiple room lets can lift total rent and spread void risk across several tenants. The flipside is a heavier regulatory load, from licensing to planning permission and higher safety standards. This article provides an introduction to what counts as an HMO, where the returns come from, how local rules can shape HMO supply and the practical steps to implement a compliant HMO strategy.

What Counts as an HMO and When You Need a Licence

In simple terms, a property let to three or more tenants who form more than two households and share a kitchen and / or bathroom is an HMO [1]. Larger HMOs with five or more occupants (from two+ households) generally require a mandatory licence from the local council [1]. Many councils also run “additional licensing” schemes that bring smaller HMOs into scope - always check your postcode before you buy or convert. License conditions typically cover minimum room sizes, amenity standards and fire-safety measures (including smoke alarms, fire doors and protected routes) [1]. Running an HMO that needs a licence without one is an offence and can lead to enforcement action and significant financial penalties, so treat the licence as part of your acquisition timeline rather than as an afterthought.

Market Size and Where Returns Come From

Industry analyses put the HMO stock in England and Wales at a market value of roughly £78 billion, with annual rents in the £6 billion+ range - evidence of how large and institutional the niche has become [4]. The core financial appeal is rental yield: typical HMO gross yields sit around ~8%, compared with lower averages for single-let buy-to-let; in stronger pockets, ranges of ~7–10% are commonly cited [2]. These higher yields come from letting by the room rather than as a single household and from value-add upgrades (e.g., adding ensuites and improving communal spaces) that support higher achieved rents. Keep in mind that higher headline yields can compress once you factor in safety upgrades, management intensity and higher wear-and-tear – you should also model net yields, not just gross.

Planning Permission and Article 4 Directions

Converting a standard house into a small HMO is a “permitted development” in many places, but not all. In numerous university and high-demand areas, councils have imposed Article 4 Directions, which remove permitted development rights such that you must now apply for planning permission even for a small HMO [3]. Large HMOs are classed “sui generis” and require mandatory planning permission everywhere [1]. Because Article 4 Directions can cover entire wards or cities, planning permission is often a big swing factor in whether an HMO investment would work; so, build in time and contingency for refusals and appeals, and always confirm the lawful use of any existing HMO that you buy.

Tenant Demand: Who Rents HMOs and Why

Demand is strongest where students and young professionals cluster - university cities and employment hubs. Affordability is a persistent driver: renting a quality room often beats the cost of a studio or one-bed flat, while still offering privacy and a social living setup. Professional “co-living” HMOs (good kitchens, fast broadband, managed housemate mix and regular cleans) can command a premium to basic shared houses. Where supply is tight, student groups will reserve early for the academic year; in city-centre professional markets, rooms can be easily let out year-round. The implication for landlords: design for the tenant you want (student vs professional), spec to their expectations and manage the HMO like a hospitality product.

Where the Numbers Look Best

Regional yield stories vary. Northern and Midlands cities often report stronger headline yields than the South, reflecting lower capital values and resilient multi-tenant demand. Investor roundups repeatedly cite cities such as Manchester, Leeds, Birmingham and Nottingham as HMO hotspots, with illustrative gross ranges commonly falling in the ~7–10% band in stronger micro-markets [3]. London holds a large share of total HMO value and generates substantial annual rent, but entry prices mean yields tend to be thinner than in northern cities [4]. As ever, results are hyper-local: two streets apart can mean different licensing and planning burdens, tenant profiles and achievable rents - use achieved comparables, not just listings, before you commit.

Cash Flow, Costs and Risk Management

Capital Expenditure

Many HMO investments need upfront compliance-related spend: fire doors, interlinked alarms, emergency lighting, upgraded electrics and extra bathrooms. Get a pre-purchase survey that covers licensing and planning requirements.

Operating costs

Expect higher utility, cleaning and maintenance costs than for a single let. In “bills-included” houses, build buffers; consider installing sub-meters or smart monitoring to track usage.

Voids and turnover

Multi-let income is more resilient to a single let void, but professional HMOs can see higher churn. Budget for reletting costs and light refreshes.

Management intensity

HMOs require more intensive management. If you are hands-off, vet and engage agents with real HMO experience; their fee quotes will probably reflect the extra work.

Compliance drift

Licence and planning conditions change; rules tighten. Create a compliance calendar (gas/electrical certificates, alarm testing, licence renewals etc.) and audit quarterly.

Finance

Specialist lenders may ask for higher deposits, stronger rental coverage and an HMO-experienced valuer’s report. Keep borrowing at prudent LTVs so that rising rates don’t strain cash flow inordinately.

Step-By-Step: De-Risk Your Next HMO

1. Map regulation first. Check Article 4 planning directions and any mandatory or additional licensing requirements at postcode and individual property level. If buying “with HMO use”, confirm lawful use and planning and licensing status in writing.

2. Model conservative yields. Underwrite on achieved local room rents, not optimistic listings. Carry out sensitivity analysis for higher utility bills and a void room or two from time to time.

3. Specify to win your tenant. For students: desks, storage, soundproofing and location. For professionals: ensuites where viable, good Wi-Fi and quality communal space.

4. Plan capex amounts and timelines. Price fire-safety upgrades, kitchens and bathrooms before exchange; align works with the planning and licence conditions you expect to receive.

5. Choose the right finance. Many HMO products require tougher stress tests than standard BTL products.

6. Operational playbook. House rules, responsive maintenance, monthly cleans and rapid re-letting processes can keep occupancy and reviews strong.

FAQs

Q. When do I legally need an HMO licence?

A. In most of England, if five or more people from two or more households share facilities, you need a mandatory HMO licence; many councils also require “additional” licences for smaller HMOs - always check locally.

Q. Do I need planning permission to create a small HMO?

A. It depends on the area. If there are no Article 4 Directions in place, a proposed conversion to a small HMO use is often permitted development. In Article 4 areas, however, you will need planning permission even for small HMOs. Larger HMOs always require planning permission.

Q. What gross yields should I expect?

A. As a rule of thumb, HMOs often achieve around ~8% gross, with ~7–10% common in stronger market - but net yields depend on capex, management and bills.

Q. How big is the HMO market?

A. The England and Wales HMO stock is valued at roughly £78 billion, generating £6 billion+ in annual rent. Local policy changes, such as Article 4 Directions for planning permission even for small HMOs, can materially affect local supply.

Q. What are the biggest pitfalls for first-time HMO investors?

A. Buying in an Article 4 area without realising it, under-budgeting for safety upgrades and overestimating achievable rent. Start with regulation, price works before exchange and validate rents with achieved comparables.