If you are buying property in London to convert into HMOs, one of the first things you need to check is whether the borough has an Article 4 Direction in place. It changes everything about how the project works - from the timeline to the level of design input required to the overall viability of the deal.
This guide explains what Article 4 means in practice, which London boroughs currently have these directions in place, and how to navigate the planning system when they do.
What is an Article 4 Direction?
Under normal circumstances, converting a house (C3 use class) into a small HMO (C4 use class, for 3 to 6 people) is classed as permitted development. That means you can make the change without applying for planning permission, in the same way you can build a small rear extension without planning.
An Article 4 Direction is a planning order that removes this specific permitted development right within a defined area. Once an Article 4 is in place, you must apply for full planning permission before changing a property from C3 to C4.
It is important to understand what Article 4 does not do. It does not ban HMO conversions. It does not automatically mean your application will be refused. It simply means the council gets to assess each proposal on its merits - location, design, impact on neighbours, concentration of HMOs in the area - before deciding whether to approve it.
Why do boroughs introduce Article 4 Directions for HMOs?
The usual reason is that a borough has experienced a rapid increase in HMO conversions and wants more control over where they happen. In areas where a large proportion of houses have already been converted, councils are concerned about the impact on the character of the neighbourhood, the strain on parking and waste services, and the reduction in family housing stock.
From a developer's perspective, Article 4 adds time and cost to the project (the planning application typically takes 8 to 12 weeks and costs £258 plus professional fees for drawings and supporting documents). But it also has a secondary effect that works in your favour - it limits new competition. Once planning permission is required, fewer amateur conversions happen, which supports rental values and reduces the oversupply problem.
Which London boroughs have Article 4 Directions for HMOs?
The landscape changes regularly as boroughs introduce new directions or modify existing ones. Here is the position as we understand it in mid-2026. Always verify with the specific borough before exchanging on a property - this table is a starting point, not a guarantee.
Boroughs with borough-wide or significant Article 4 coverage
| Borough | Article 4 scope | Concentration limit |
|---|---|---|
| Newham | Borough-wide | Yes - typically 10% within 50m radius |
| Tower Hamlets | Borough-wide | Yes |
| Haringey | Borough-wide | Yes - 10% threshold |
| Southwark | Borough-wide | Yes |
| Barking & Dagenham | Borough-wide | Yes - 20% within 100m |
| Waltham Forest | Borough-wide | Yes |
| Brent | Significant areas | Yes |
| Redbridge | Borough-wide | Yes |
Boroughs with area-specific or emerging Article 4 coverage
Several boroughs have Article 4 Directions that cover specific wards or neighbourhoods rather than the whole borough. Others have been consulting on new directions or have them in the pipeline. These include Lewisham, Lambeth, Enfield, Ealing, and Greenwich. The trend is clearly towards more boroughs adopting Article 4 for HMOs, not fewer.
Boroughs without Article 4 for HMOs
Some London boroughs have not introduced Article 4 Directions for HMOs. In these areas, small HMO conversions (C3 to C4) can still proceed as permitted development. However, large HMOs (sui generis, 7+ people) always need planning permission regardless of Article 4 status.
Boroughs without Article 4 for HMOs tend to be either less affected by HMO concentration or have other policy tools they use instead. But the absence of Article 4 does not mean planning is irrelevant - you still need to comply with building regulations, HMO licensing, and any other local policies.
How concentration limits work
Many boroughs with Article 4 Directions also apply a concentration test when assessing HMO planning applications. The most common approach is to check what percentage of properties within a certain radius are already HMOs. If the proportion exceeds the threshold - typically 10% to 20% - the application is likely to be refused.
The radius varies by borough. Some use 50 metres from the application site, others use 100 metres. Some count all HMOs (licensed and unlicensed), while others only count those with planning permission or a licence on record.
What this means in practice is that you should check the HMO density around a property before you buy it, not after. Your architect or planning consultant can do this search as part of a feasibility assessment. We do this routinely for developers considering HMO conversions across London and it takes about a day to get a clear picture.
What does a successful HMO planning application look like?
When you do need to apply, these are the things that planning officers typically assess:
- HMO concentration: Is the area already saturated with HMOs? If so, the application will likely be refused regardless of how good the design is.
- Quality of accommodation: Room sizes, natural light, ventilation, outdoor space, communal facilities. The better the quality, the stronger the case.
- Impact on neighbours: Noise, parking, waste, overlooking. Officers want to see that the HMO will not cause demonstrable harm to neighbouring properties.
- Design quality: Does the proposal maintain or enhance the character of the street? Externally, the building should look no different from its neighbours. Internally, the layout should be well thought through.
- Management: Some boroughs want to see a management plan showing how the property will be maintained, how waste will be handled, and who the point of contact is for complaints.
A well-prepared application with proper architectural drawings, a thorough design and access statement, and evidence that the scheme meets all relevant standards has a strong chance of approval - even in boroughs with Article 4. The applications that fail tend to be the ones submitted by developers who did not take the planning process seriously.
What about large HMOs (sui generis)?
If you are planning an HMO for 7 or more occupants, the change of use is classified as sui generis - meaning it falls outside the standard use classes altogether. This always requires planning permission, regardless of Article 4 status.
Sui generis applications are assessed on similar criteria to C4 applications but tend to receive more scrutiny. The council will look closely at room sizes, communal facilities, fire safety provisions, parking impact, and the potential effect on the character of the area.
Many of the HMO projects we work on are sui generis because the developers are maximising bedroom count through extensions and loft conversions. The planning process takes a few weeks longer, but approval rates are reasonable provided the design is sound and the location is appropriate.
Tips for developers working in Article 4 boroughs
- Check before you buy. Run an HMO concentration check around the property. If the area is already at or above the threshold, move on to a different property.
- Budget for planning. An Article 4 application adds roughly £8,000 to £15,000 in professional fees (architect, planning drawings, design and access statement) and 8 to 12 weeks to the timeline. Factor this into your deal analysis.
- Design properly. The difference between approval and refusal often comes down to the quality of the design and the supporting documentation. Invest in a good architect rather than trying to submit the bare minimum.
- Consider pre-application advice. Most boroughs offer a pre-application service where you can get informal feedback from a planning officer before submitting. It costs £250 to £600 and can save you the £258 application fee plus months of wasted time if the scheme is unlikely to succeed.
- Think about the long game. Article 4 is actually good for serious developers. It filters out amateur competition and protects rental values. If you can get planning permission, you have a stronger asset than someone who converted under permitted development in a borough without controls.
For a broader look at HMO conversions including costs, room sizes and design tips, read our complete HMO conversion guide. And if you have a specific property in mind and want to understand the planning position, get in touch - we are happy to take a quick look and tell you where things stand.