An HMO extension adds space to a shared house, usually a ground-floor bedroom with ensuite or a bigger communal kitchen. For a house in London we start with a measured survey, check the council’s written HMO standards for the number of sharers, and then price each item separately.
- Area
- Greater London, England
- Postcodes
- EC1A, EC1M, EC1N and EC1R
- Pricing region
- London
What do extensions for extra rooms in London involve?
- Planning route check and drawings
- Party wall coordination where needed
- Fire separation and detection extended to the new space
- Heating, insulation and glazing
- Kitchen or bedroom fit-out
Which rules apply in London?
Extensions for extra rooms in London must satisfy national law for England, the council’s written HMO standards and, where walls, drainage or fire separation change, the building rules. In short:
- 3–6 unrelated sharers is use class C4; changing from a family house is usually permitted development unless an Article 4 direction applies.
- A conversion can be a material change of use under the building regulations, so confirm with building control before work starts.
- Fire precautions follow a risk assessment; the LACORS Housing – Fire Safety guide (2008) is guidance, not law, but many councils base their standards on it.
- National rules ask for an adequate number of bathrooms, WCs and basins and suitably located kitchens; numeric ratios are set by each council.
How much do extensions for extra rooms cost in London?
| Item | UK typical | Local guide | Per |
|---|---|---|---|
| Single-storey extension, about 15 m² | £35,000 – £60,000 | £44,800 – £76,800 | project |
| Single-storey extension per m² | £1,800 – £4,000 | £2,300 – £5,100 | m² |
Prices in London are shown with our regional adjustment for London (above the UK average). Your quote is itemised and fixed in writing once the scope and specification are agreed.
How long does it take?
Most jobs of this kind take 8–14 weeks. If a council deadline applies in London, tell us at the first call so the programme is built around it.
When do London landlords need it?
Landlords in London most often ask us for this when:
- A kitchen too small for the number of sharers
- Moving to more sharers with consent
Questions about extensions for extra rooms in London
Can I extend an HMO under permitted development?
Some extensions to houses are permitted development, but rules differ for HMOs and by nation and council. We check the address before design.
Do you cover all of London?
Yes. We work across London and the EC1A, EC1M, EC1N and EC1R postcode areas, plus the rest of Greater London. Nearby places we also cover include City of Westminster, Pimlico, Islington.
Does a shared house in London need an HMO licence?
In England, a mandatory licence is needed for 5 or more people from 2 or more households. Smaller HMOs can need a licence where the council runs additional licensing, which is common in towns with many shared houses. Check the council’s website for the address.
How much do extensions for extra rooms cost in London?
Our guide ranges for London are in the table on this page, and the guide-price tool gives a figure for your house. A fixed written quote follows a free site visit.
Extensions for extra rooms near London
- City of Westminster · 1 mi
- Pimlico · 1 mi
- Islington · 2 mi
- Camden Town · 2 mi
- Chelsea · 2 mi
- Chalk Farm · 3 mi
- All of Greater London
Other HMO services in London
- Loft conversions for extra rooms in London
- Communal kitchen refits in London
- Layout changes and room reconfiguration in London
- Large HMO conversions (7+ sharers) in London
- Ensuite installation in London
- House to HMO conversion in London
- Licence condition and schedule-of-works in London
- Student HMO refurbishment in London