HMO Planning Permission: Article 4 and Permitted Development
Do you need planning permission for an HMO? Guide to C4 use, permitted development, Article 4 directions, room sizes and the new NPPF.
PLANNING APPLICATIONSPERMITTED DEVELOPMENT
Andrew Ransome
10/10/202612 min read
Do you need planning permission for an HMO?
Often, no. In England, turning a home into a small HMO for three to six people is usually permitted development.
But that right is switched off in a growing number of areas. And larger HMOs always need permission.
The quick answer:
Small HMO (3 to 6 people): usually no application needed, unless an Article 4 direction or a planning condition has removed the right.
Large HMO (7 or more people): planning permission is needed.
Licensing: this is a separate regime. A licence is not planning permission, and planning permission is not a licence.
This guide reflects the National Planning Policy Framework published in August 2026.
What is an HMO in planning terms?
Planning law sorts residential uses into use classes. Three matter here.
C3 dwellinghouse. A single person or household, or up to six people living together as one household. Think of a family home.
C4 small HMO. Three to six residents, forming more than one household, who share basic amenities. Think of a five-bed shared house.
Sui generis large HMO. More than six residents sharing. Think of an eight-bed HMO.
A few points catch people out:
Count residents, not bedrooms. A couple and one friend in a three-bed house is three residents and two households. That is a C4 HMO.
It must be their main home. C4 borrows its definition from section 254 of the Housing Act 2004. Students count.
Flats can be C4 too. A shared flat with three to six unrelated occupiers is a small HMO.
Seven is the tipping point. Above six residents the use falls outside C4.
The planning definition and the licensing definition are not identical. Check both.
What is permitted development?
Permitted development is planning permission granted nationally, in advance, by the General Permitted Development Order 2015. You do not apply to the council. You simply stay within the limits.
Three things to remember:
Rights come with limits and conditions. Step outside them and you need a full application.
Rights can be removed. A council can withdraw them with an Article 4 direction. A condition on an earlier permission can do the same.
Other rules still apply. Building regulations, HMO licensing, listed building consent and leases are all separate.
HMO permitted development rights: C3 to C4 under Class L
Class L of Part 3 of Schedule 2 to the Order is the key permitted development right for small houses in multiple occupation (HMOs). It allows a change of use:
from a C3 dwellinghouse to a C4 small HMO; and
from a C4 small HMO back to a C3 dwellinghouse.
No prior approval application is required under Class L. However, the right is subject to specific limitations and must not have been withdrawn or restricted in the particular case.
Class L can apply to houses and flats. For the purposes of Part 3, the Order's definition of a dwellinghouse includes a building containing flats and individual flats themselves.
There are important limitations:
No subdivision into separate dwellings. Class L does not permit a change that would result in a building previously used as a single C3 dwellinghouse or C4 HMO being used as two or more separate dwellings of the relevant use class.
Large HMOs are excluded. Class L covers changes between C3 and C4 only. A change to a large HMO, which falls outside Use Class C4 and is generally treated as sui generis, is not authorised by this right.
Some properties are excluded. Certain dwellings created under other permitted development rights are subject to restrictions on subsequent changes of use. The planning history and relevant conditions should therefore be checked.
Article 4 directions may apply. Some councils have withdrawn the right to change a C3 dwellinghouse to a C4 HMO in specified areas. Check the council's current directions before proceeding.
Should you apply for a lawful development certificate?
A lawful development certificate is not a prerequisite for relying on Class L. However, applying to the local planning authority can provide formal confirmation that the existing or proposed use is lawful, provided sufficient evidence is supplied.
It can be particularly useful when letting a property, arranging finance or selling it, as it provides documentary evidence of the planning position. It does not replace any necessary HMO licence or other regulatory approval.
Can you extend an HMO under permitted development?
Yes, in many cases. This is a permitted development right that HMO landlords may overlook.
Householder permitted development rights under Part 1 of Schedule 2 to the General Permitted Development Order 2015 apply to a “dwellinghouse”.
The courts have established that the key test is whether a building provides the facilities needed for day-to-day private domestic existence. In Gravesham Borough Council v Secretary of State for the Environment (1982), the court considered this defining characteristic of a dwellinghouse.
In London Borough of Brent v Secretary of State for Levelling Up, Housing and Communities [2022] EWHC 2051 (Admin), the High Court confirmed that a dwellinghouse in use as a small HMO can benefit from householder permitted development rights.
This means a C4 HMO that qualifies as a dwellinghouse may be able to rely on rights including:
Rear extensions (Class A). Single-storey extensions can generally project up to 3 metres beyond the original rear wall of a terraced or semi-detached house, or 4 metres for a detached house. Larger extensions of up to 6 metres or 8 metres respectively may be possible under the prior approval procedure, subject to the relevant conditions.
Side extensions (Class A). These must be single-storey, no more than 4 metres high and no wider than half the width of the original house.
Loft conversions (Class B). Roof enlargements may be possible, subject to the relevant restrictions, including a maximum additional roof volume of 40 cubic metres for a terrace house or 50 cubic metres for other houses.
Rooflights (Class C) and porches (Class D). These may be permitted, subject to their respective limitations and conditions.
Outbuildings (Class E). Buildings within the garden may be permitted where they meet the relevant requirements and are for purposes incidental to the enjoyment of the dwellinghouse. An outbuilding used as additional HMO accommodation would not ordinarily qualify simply because it is in the garden.
What are the exceptions?
Flats and buildings containing flats. These are excluded from the definition of a dwellinghouse for these purposes. Householder permitted development rights therefore do not apply to a flat within a converted house or to a building containing flats.
Large HMOs. A property occupied by more than six residents falls outside Use Class C4.
Designated areas. Restrictions apply in conservation areas and National Landscapes (formerly Areas of Outstanding Natural Beauty). For example, roof enlargements under Class B are not permitted development on Article 2(3) land.
Planning conditions and Article 4 directions. Earlier planning permissions may have removed relevant permitted development rights, and an Article 4 direction may withdraw them in a particular area.
Changes in the number of residents. An extension does not itself authorise a change to a large HMO. If the property is to accommodate more than six residents, that will require planning permission.
The Brent judgment confirms that an otherwise qualifying dwellinghouse can benefit from householder permitted development rights while in C4 use. It also makes clear that the status of the property and the circumstances at the relevant time matter.
The judgment should not be read as a blanket entitlement for every HMO to extend without planning permission.
Before starting work, check the property's planning history, any Article 4 direction, and all applicable limitations and conditions.
Where there is uncertainty, a lawful development certificate can provide formal confirmation of the planning position.
What is an Article 4 direction?
An Article 4 direction is a legal order made by a council. It can remove a specific permitted development right in a defined area.
It means you must apply for planning permission, and the council decides the application against its adopted planning policies.
National policy supports their use for HMOs. Policy DM10 of the NPPF names "small Houses in Multiple Occupation" as an example of an over-concentration of uses that can justify a direction.
DM10 also sets three tests. A direction should be:
necessary to protect local amenity or the wellbeing of the area;
based on robust evidence; and
applied to the smallest area needed to deal with the harm.
How an Article 4 direction affects HMO permitted development
Most HMO directions do one thing. They withdraw the Class L right to change from C3 to C4.
That has knock-on effects worth knowing.
It is not retrospective. An HMO in lawful C4 use before the direction took effect can carry on.
It is usually a one-way valve. The right to go from C4 back to C3 often survives. But if let the house to a single family and you may need permission to return to HMO use.
Large HMOs are unaffected. They needed planning permission anyway.
Extension rights might survive. A direction only removes the rights it names. Read the sealed direction carefully.
Boundaries vary. Some cover a whole borough. Others cover a few streets.
Where are HMO Article 4 directions in force?
Many councils now use them, and the number is rising fast. These examples show the spread. Dates are when the direction took effect.
London - for example, Barking and Dagenham, Newham, Enfield, Barnet, Croydon, Brent, Hounslow, Lewisham, Ealing, Hillingdon, Merton, Harrow, Havering
Kent - for example, Thanet, Dartford, Medway, Swale
Other cities - for example, Southampton, Birmingham, Brighton and Hove
This list is not complete, and it changes monthly. Always check the council's own Article 4 page and map.
What does the NPPF say about HMOs?
The National Planning Policy Framework has coded policies, split between plan-making and decision-making.
There is no stand-alone HMO policy. The only express mention is in DM10, on Article 4 directions. But several national decision-making policies bear directly on HMO applications.
S3 and S4: the presumption. Development within settlements should be approved unless the benefits are substantially outweighed by adverse effects. Most HMOs are in towns, so the starting point favours approval.
HO7: housing need. Substantial weight goes to homes that meet evidenced local needs. Renters and students are named groups whose needs plans should assess.
L2 and L3: effective use of land. Substantial weight goes to better use of underused buildings, and density should rise within settlements. An HMO houses more people in the same building.
P3: living conditions. Development should give healthy living conditions and avoid unacceptable noise or loss of light for neighbours. This is a common ground for refusal.
DP3: design. Proposals should respond to context and meet explicit local design standards. Room size and amenity standards in the local plan carry real force.
TR4 and TR6: parking and highways. Parking should suit the location. A parking objection will need evidence to overcome it.
DM7: other regimes. Planning should not duplicate other regulatory controls. Licensing handles management. Planning handles land use.
DM8: unauthorised development. An intentional breach counts heavily against retrospective permission. Converting first and applying later is now riskier.
Applications are decided in line with the development plan unless material considerations indicate otherwise.
How councils assess an HMO planning application
Most HMO decisions turn on the same handful of issues.
Concentration. How many HMOs are already nearby, measured against the local threshold.
Character. Whether the street is still a mixed and balanced community.
Living conditions for occupiers. Bedroom sizes, communal space, light, outlook and outdoor space.
Living conditions for neighbours. Noise, disturbance and comings and goings.
Parking and cycle storage. Judged against local standards and on-street capacity.
Bins. Enough storage, out of sight, with a route to the kerb.
Loss of a family home. Often decisive in London and the South East.
Need is the issue applicants most often under-evidence. In Goodman v SSHCLG [2019], the High Court looked at how an inspector dealt with evidence of need for HMOs. The lesson is practical. A decision-maker must form a view on the strength of your evidence. So give them something solid to weigh.
In this case, evidence from local letting agents was not considered sufficient to demonstrate the identified need required by local planning policy. The judgment illustrates the difference between showing that there may be demand for HMO accommodation and providing persuasive evidence of a specific local need. Applicants should therefore consider including local housing data, evidence of demand from prospective tenants, information about the availability of existing HMO accommodation and any relevant shortfall in shared housing provision. The strength of the evidence will depend on the wording of the policy and the circumstances of the proposal.
A strong application usually includes:
scaled floor plans with every room size marked;
a street-by-street count of existing HMOs within the policy radius;
evidence of local demand for shared housing;
a short management plan;
a parking survey, where parking is tight; and
bin and cycle store details.
Expect conditions. An occupancy cap, bin storage and cycle parking are standard.
HMO room sizes: the legal minimum and what planners expect
Room sizes come from two places. Licensing sets a legal minimum. Planning policy and local HMO standards may expect more.
Licensing minimums
In England, mandatory HMO licensing generally applies where five or more people from two or more separate households live in an HMO, subject to specific exemptions. Since 1 October 2018, the rules have applied regardless of the number of storeys. Many councils also license smaller HMOs through additional licensing schemes.
For HMOs requiring a licence under Part 2 of the Housing Act 2004, the licence must include these minimum sleeping room sizes:
One person aged over 10: 6.51 sqm.
Two people aged over 10: 10.22 sqm.
One child aged under 10: 4.64 sqm.
The detail matters:
A room smaller than 4.64 sqm cannot be used for sleeping accommodation.
Floor area beneath a ceiling lower than 1.5 metres does not count.
A generous lounge cannot compensate for a bedroom that falls below the statutory minimum.
Licences must also require compliance with the council's household waste storage and disposal scheme, where one exists.
Government guidance is clear. These are statutory minimums, not optimal room sizes. Councils can impose higher standards through licence conditions, but cannot set lower minimums.
Planning standards
Planning policies and local HMO standards can go further. For example:
Birmingham: its development management standards specify bedrooms of at least 7.5 sqm for single occupancy and 11.5 sqm for double occupancy.
Essex: the Essex HMO Amenity Standards specify 8.5 sqm for a single-occupancy bedroom where the kitchen is shared but there is no shared living room.
Communal space: local standards may also set minimum kitchen, lounge and dining areas according to the number of occupiers.
These examples are not universal rules. Local standards differ, and their status varies: some form part of planning policy, while others are housing or licensing standards that may also be material considerations in planning decisions.
Design to the applicable local standard, not simply the national licensing minimum.
A scheme that meets the statutory bedroom size requirements can still be refused planning permission if the overall accommodation would provide an unacceptable standard of living conditions.
Coordinate planning and licensing
Planning permission and an HMO licence are separate requirements. Securing one does not automatically secure the other.
Councils may check planning status before issuing a licence and, where possible, to process the two consents in parallel. Check the relevant council's planning policies, HMO guidance and licensing conditions before finalising a layout.
The Benefits of HMOs
HMOs often attract objections during planning applications. But they also do a job no other housing does. The benefits may include:
Lower-cost homes. A room costs less than a flat. Government guidance calls HMOs a vital part of the private rented sector.
Homes for people the market overlooks. Students, young professionals, key workers and people between homes all rely on them.
Better use of existing buildings. More people are housed without building on new land.
Support for local employers. Hospitals, universities and town centre businesses need nearby homes for staff.
Flexibility. Shared homes suit people moving for work or study.
Investment in older stock. Conversion often brings large or tired houses back into good repair.
Sustainable locations. HMOs cluster near centres and transport, where car use is lower.
The NPPF gives substantial weight to homes that meet evidenced needs, and to better use of underused buildings.
Is your existing HMO lawful?
An HMO is lawful in planning terms if one of three things is true.
It was created under Class L. The C4 use began before any Article 4 direction took effect.
It has planning permission. Check the conditions, especially any occupancy cap.
It is immune from enforcement. The use has continued, without a break, for ten years.
You can prove any of these with a lawful development certificate. The test is the balance of probabilities. Useful evidence includes:
tenancy agreements and deposit records;
council tax and HMO licence records;
utility bills and letting agent statements; and
dated photographs and sworn statements.
Two traps are worth flagging.
Losing the use. A short void does not end a lawful HMO use. A let to a single family might. In an Article 4 area you would then need permission to go back.
Self-contained rooms. Adding en-suites is fine. Adding full kitchens to every room risks creating separate flats. In Welwyn Hatfield BC v SSLUHC [2022], a house with four self-contained bedsits stayed a single C4 HMO. The shared kitchen, lounge and garden were the reason. Keep real communal space.
Ignoring an enforcement notice is n offence. As is pperating without a required HMO licence. And under NPPF policy DM8, an intentional breach now weighs heavily against a retrospective application.
HMO planning FAQs
Do I need planning permission to turn my house into an HMO?
Not usually, for three to six residents. That change is permitted development under Class L. You do need permission if an Article 4 direction applies, if a condition removes the right, or if there will be seven or more residents.
What is the difference between C3 and C4?
C3 is a home occupied by a single person or household.
C4 is a home shared by three to six people from more than one household.
More than six sharers is a large HMO, which sits outside the use classes.
Can I get planning permission for an HMO in an Article 4 area?
Yes. A direction removes the automatic right, not the possibility. Applications succeed where they meet the local HMO policy, typically on concentration, living conditions and parking.
Does an HMO licence mean I have planning permission?
No. Licensing and planning are separate. You can hold a licence and still be in breach of planning control.
Can I extend an HMO without planning permission?
Sometimes. A small HMO that is a house can usually use householder permitted development rights for rear extensions and loft conversions. Flats cannot.
What are the minimum room sizes for an HMO?
Under mandatory licensing, 6.51 sqm for one adult and 10.22 sqm for two. Many councils require more through licensing standards or planning policy.
How long before an unauthorised HMO becomes lawful?
Ten years of continuous use. A lawful development certificate confirms the position.
Get advice on an HMO scheme
If you are weighing up an HMO purchase, conversion or application, have the current policy position checked before you commit.
Get in touch at me to talk through your site and explore the planning position.
Andrew Ransome MRTPI - Email: andrew@andrewransome.co.uk
About me
Andrew Ransome is a Planning Director and a Chartered Member of the Royal Town Planning Institute (RTPI), with more than two decades of experience in town planning.
He specialises in delivering strategic planning solutions for complex developments across both rural and urban environments, helping clients navigate planning challenges and unlock development opportunities. Connect with Andrew on Linkedin.
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