An HMO extension adds space to a shared house, usually a ground-floor bedroom with ensuite or a bigger communal kitchen. Landlords in Portsmouth (PO1, PO4 and PO5) usually come to us with a council letter, a fire risk assessment or a house they have just bought. We price from whichever you have. With students as well as working sharers renting in Portsmouth, we plan bigger jobs for the gap between academic-year tenancies where we can.
- Area
- Hampshire, England
- Postcodes
- PO1, PO4 and PO5
- Location
- 15 miles south-east of Southampton
- Council
- Portsmouth City Council
- Pricing region
- South East
What do extensions for extra rooms in Portsmouth involve?
- Party wall coordination where needed
- Fire separation and detection extended to the new space
- Foundations, structure and roof
- Planning route check and drawings
- Ensuite drainage and extraction
Which rules apply in Portsmouth?
The rules below are the England-wide position for this kind of work. Councils add their own standards and schemes on top, so we always check the address in Portsmouth before we price.
- 7 or more sharers is a sui generis large HMO and normally needs planning permission.
- A conversion can be a material change of use under the building regulations, so confirm with building control before work starts.
- The Fire Safety Order 2005 applies to the common parts of HMOs, enforced by the fire and rescue authority.
- National rules ask for an adequate number of bathrooms, WCs and basins and suitably located kitchens; numeric ratios are set by each council.
Portsmouth City Council: local HMO schemes
| Article 4 (HMO) | In force across the council area Covers the whole city; in force since November 2011. |
|---|---|
| Additional licensing | In force across the council area City-wide additional HMO licensing 1 Sep 2023-31 Aug 2028. |
| Selective licensing | No scheme found |
Schemes change. Check the council’s current pages for the exact address in Portsmouth before you buy or start work. Source: Portsmouth City Council HMO licensing page, checked 2026-10-31.
How much do extensions for extra rooms cost in Portsmouth?
| Item | UK typical | Local guide | Per |
|---|---|---|---|
| Single-storey extension, about 15 m² | £35,000 – £60,000 | £39,200 – £67,200 | project |
| Single-storey extension per m² | £1,800 – £4,000 | £2,000 – £4,500 | m² |
Prices in Portsmouth are shown with our regional adjustment for South East (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 Portsmouth, tell us at the first call so the programme is built around it.
If the house is let to students, we work backwards from the next tenancy start date in Portsmouth.
When do Portsmouth landlords need it?
Typical reasons for this work in Portsmouth:
- A kitchen too small for the number of sharers
- Adding a ground-floor room
Questions about extensions for extra rooms in Portsmouth
Will the extension affect neighbours?
Possibly, if it is on or near a boundary. Party wall procedures may apply in England and Wales.
Which postcodes in Portsmouth do you work in?
All of them, including PO1, PO4 and PO5, and the surrounding parts of Hampshire.
Which council covers HMOs in Portsmouth?
Portsmouth is covered by Portsmouth City Council. We read the council’s written HMO standards before pricing, and you should check the licence position for the exact address.
How much do extensions for extra rooms cost in Portsmouth?
Our guide ranges for South East 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 Portsmouth
- Gosport · 2 mi
- Fareham · 5 mi
- Ryde · 6 mi
- Havant · 6 mi
- Waterlooville · 6 mi
- Cowes · 9 mi
- All of Hampshire
Other HMO services in Portsmouth
- Loft conversions for extra rooms in Portsmouth
- Communal kitchen refits in Portsmouth
- Layout changes and room reconfiguration in Portsmouth
- Large HMO conversions (7+ sharers) in Portsmouth
- Ensuite installation in Portsmouth
- House to HMO conversion in Portsmouth
- Professional and co-living HMO refurbs in Portsmouth
- Small HMO conversions (3–6 sharers) in Portsmouth