Definition of a Large HMO
Legally, a Large HMO is a property rented out to 5 or more tenants forming 2 or more households. A household typically refers to individuals who are related (family members) or living as a couple.
What is a Sui Generis HMO?
A Sui Generis HMO refers to an HMO that falls into its own planning category in UK planning law. The term Sui Generis, Latin for “of its own kind,” is used to describe properties that do not fall into standard planning categories.
A Sui Generis use class applies to Large HMOs with 7 or more unrelated occupants sharing facilities and requires special planning permission. If you operate a Large HMO with 7+ tenants, or are planning to, you will need to ensure you understand how to do a Sui Generis planning application. We have a guide which goes into more detail on this.
Sui Generis: What you need to know >
This means that all Sui Generis HMOs are Large HMOs, but not all Large HMOs are Sui Generis.
Some Large HMOs fit into the C4 use class. The C4 use class is used for HMOs between 3-6 occupants. However, when it comes to what is considered a legal Large HMO for licensing purposes, it is 5+ tenants. The difference between Sui Generis and Large HMO can sometimes be confusing, so it’s important to understand the differences.
Mandatory HMO Licence for Large HMOs
In the UK, the Mandatory Licence for Large Houses in Multiple Occupation (HMOs) is a requirement under the Housing Act 2004 for Large HMOs – i.e. any HMO that has 5 occupants or more. This ensures that the property meets specific standards to protect tenants, as larger shared properties can be more susceptible to poorer living standards if not properly regulated.
The Mandatory Licence for Large HMOs reviews areas such as whether the property is safe for occupants when it comes to fire safety, gas safety, and adequate facilities (e.g. appliances, furniture etc.). This includes checking for things like smoke alarms and a gas safety certificate. A mandatory HMO licence typically lasts up to 5 years but may vary depending on the council.
In addition, the licence ensures the property is not too overcrowded and has adequate living space for tenants, enforced through minimum room size requirements. You as a landlord may also have background checks conducted, looking at things such as criminal history or checking for any previous housing related offences.
For more details, you can read our full guide on HMO Licensing >
Room Size Requirements for Large HMOs
Bathroom Requirements for Large HMOs
For large HMOs over 5 tenants, you will need separate toilets from the main bathroom so that your occupants don’t have any trouble with showers being occupied when they need to use the toilet, or vice versa. If you have ensuite bathrooms to some of your bedrooms, you can subtract those occupiers and bathrooms before you calculate how many communal bathrooms you need.
In terms of the number of bathrooms required, this depends on the occupancy of your Large HMO. Below is a table illustrating Large HMO bathroom requirements:
| Occupancy | Number of HMO Bathrooms Required |
| 5 tenants | 1 toilet with a wash basin in addition to a main bathroom or bathrooms |
| 6-10 tenants | 2 toilets with 2 bathrooms, one of which can be within one of the main bathrooms |
For more information on bathroom sizes for HMOs, read our Bathroom Size Requirements Guide >
Kitchen Requirements for Large HMOs
In a Large HMO, the kitchen must be large enough to comfortably accommodate all occupants sharing the space. To ensure suitability, there are established regulations governing the required kitchen size.
| Occupancy | Minimum Kitchen Size for HMO |
| 5 tenants | 7m2 |
| From 6-10 tenants | Between 8m2 – 10m2 |
| More than 10 tenants | Second kitchen required |
There are also rules regarding worktop sizes, facilities and more. For more information, read our full article on HMO room size requirements >
Bedroom Requirements for Large HMOs
Bedroom requirements for HMOs are on a tenant by tenant basis, and the minimum room sizes apply to all HMOs whether they are Large HMOs or regular HMOs. In general, the minimum room size for one adult occupant is 6.52 square metres and for two occupants is 10.22 square metres. Again, more details on bedroom size requirements are covered in our article.
Are Large HMOs a good investment option?
Pros of Large HMOs
For landlords, Large HMOs often yield higher rental income compared to renting a property as a single unit. Because the rental income is derived from multiple tenants, it reduces the risk of a total vacancy affecting your income, so it can be a worthwhile investment.
Other benefits of investing in Large HMOs is demand, particularly in cities with high student populations or working professionals who will be looking for comfortable but affordable housing. Given that there are housing shortages in many cities, HMOs are in demand and, therefore, can be an excellent investment choice. There is also overall property value, given that Large HMOs often involve property conversion or improvement, this means investors can add value and generate more equity growth. Costs like utilities, maintenance, and management can also be spread across more tenants, maximising profitability.
Cons of Large HMOs
As detailed in this article, there is more management and effort involved when it comes to investing in Large HMOs, given the licensing requirements and need to secure planning approval in some cases. In addition, the initial investment in a Large HMO can be considerably higher than a standard HMO, particularly if there is a need to convert the property before it can be occupied.
Other downsides of Large HMOs include more intensive management, given that there will be occupants to manage in a property, more individual rent to collect and more overall use of facilities and services in the property, overall management and maintenance can be more challenging when compared to standard HMOs. Large HMOs can also face resistance from neighbours and councils due to concerns over noise, parking, and anti-social behaviour.
Other considerations for Large HMO investment
When it comes to investing in Large HMOs, there are some key things that need to be considered once all the pros and cons have been taken into account.
Location
Consider the location for your Large HMO. Cities with strong student, professional, or transient populations are good, as well as areas with good transport links and amenities.
Cost vs Return
You should consider the total cost of the property purchase, licence, conversion costs and ongoing management compared with your total expected retinal income to ensure a strong rental yield. An HMO feasibility checker can help you calculate this.
Article 4
If you are looking to invest in a Large HMO in a city, it’s best to check on whether there are Article 4 directions in place before you look to invest. We have a full guide on Article 4 Directions >
Finance
If you are looking to finance a Large HMO, you will want to ensure you are obtaining a finance option that is most suitable for a Large HMO. Lenders offer specific HMO mortgages, so ensure you’re clued up on HMO financing >.
Large HMO mortgage
The main difference between a standard HMO mortgage and a large HMO (Sui Generis) mortgage is that a mandatory HMO licence is always required to obtain a large HMO mortgage. Large HMOs also tend to face stricter lending criteria due to their size and complexity.
Conclusion
Large HMOs can be a highly lucrative property investment option, offering stable, high income potential, particularly in high demand areas. However, they do tend to be more suited to investors who already have experience in property investment or are willing to hire professionals to help with management, given the higher management and regulatory requirements involved with Large HMO investing.
If these align with your goals and resources, Large HMOs can indeed be a rewarding investment.
