A loft conversion turns unused roof space into a habitable room such as a bedroom, bathroom or office, with a proper staircase, insulation, fire protection and natural light from rooflights or a dormer.
Planning a loft conversion for a home in Portsmouth means making a handful of decisions about materials, layout, finish and timing. We help you work through them at a free survey, then confirm in writing what it will cost for the options you pick. Most projects of this type need 6–10 weeks on site, and we cover every PO1, PO2, PO3 and PO4 address as well as the rest of Hampshire.
- Guide price
- £33,500–£73,000 inc VAT
- Time on site
- 6–10 weeks on site
- Postcodes
- PO1, PO2, PO3, PO4 and PO5
- Planning rules
- England
- Local area
- Hampshire
- Survey
- Free, with a written quote
What should you budget for a loft conversion in Portsmouth?
To help you plan, we show what a loft conversion typically costs in Portsmouth instead of holding figures back for a sales call. The range is £33,500–£73,000 with VAT, using rates in the South East that are about 12% above the national guide. A free survey then fixes your actual price.
| Type of job | What it usually involves | Guide in Portsmouth |
|---|---|---|
| Rooflight conversion | Rooflights in the existing slope, a new floor, staircase and insulation, where head height already works. | £22,500–£39,000 |
| Dormer conversion | A rear dormer adding headroom and floor space, often with a bedroom and shower room. | £36,000–£67,000 |
| Hip-to-gable or mansard | Larger structural changes to the roof for the maximum usable space. | £56,000–£95,000 |
Expect these to shape the final quote:
- Conversion type: rooflight, dormer, hip-to-gable or mansard
- Floor area, existing head height and roof structure
- Steelwork and any strengthening of walls below
- Adding a shower room or en-suite in the roof
What’s included?
- Structural calculations and steel beams where needed
- New floor joists strong enough for a habitable room
- Dormer, hip-to-gable or rooflight structure as agreed
- Insulation to walls, roof slope and floor
- Fire doors, mains-linked smoke alarms and a protected escape route
- Electrics, heating and plumbing by qualified trades, with certificates
Local housing and a loft conversion
Southampton and Portsmouth have dense Victorian terraces, with plenty of post-war rebuilding after wartime bombing. Winchester keeps Georgian and medieval streets, Basingstoke expanded rapidly with 1960s and 1970s estates, and New Forest villages feature cob, thatch and brick. Brick and flint is common on the chalk downs, and new estates ring most towns.
Terraces suit loft rooms and side-return extensions; post-war and expanded-town homes often need window, roofline and cladding renewal. Cottages in the Forest may call for lime repairs and planning-sensitive windows.
With that background in mind, here is how we typically handle a loft conversion for homes in Portsmouth, from the first visit to the finished result.
Permissions for a loft conversion in Portsmouth
As Portsmouth is in England, read the following with that system of planning and building control in mind. We check what applies to your house with the council before you receive a quote.
In England, many loft conversions are permitted development: up to 40 m³ of extra roof space on a terraced house and 50 m³ on a semi-detached or detached house, no dormer on the front roof slope facing a road, nothing higher than the existing roof, and similar-looking materials. Conservation areas, listed buildings and flats need planning permission.
Building Regulations approval is always needed for a loft conversion: floor strength, a proper staircase, insulation, fire-protected escape route and smoke alarms. The Party Wall etc. Act 1996 usually applies on attached houses.
Rules change and every property is different, so we check the planning history and constraints for your address before we quote.
What happens after you get in touch?
Free site survey
We begin by looking at the job in person. During the free survey we discuss options, materials and budget for a loft conversion, and photograph or measure anything the quote needs to reflect.
Quote in writing
You get the price in writing, itemised so you can see where the money goes. As long as the specification stays the same, that is the price you pay for a loft conversion.
Dates and permissions
Before anyone starts, we confirm the programme in writing, check whether consents are required and arrange deliveries. If a skip or scaffolding on the road needs a permit, we apply for it.
The work itself
Work goes ahead as scheduled and you deal with one contact throughout. When the last trade leaves, we clear and clean the site, talk you through what has been done and pass on any certificates and care instructions.
How we work
Common questions
How long will a loft conversion take?
On a typical home, allow 6–10 weeks on site. Larger projects, older buildings and extra work found once things are opened up can extend that, while simpler jobs may be shorter. Your quote includes an estimate of time on site, and your point of contact keeps you updated on the programme as the work progresses.
How much does a loft conversion cost?
A typical dormer loft conversion on a 3-bed semi costs £33,500–£73,000. A simple rooflight conversion costs less, while hip-to-gable and mansard conversions cost more because they change the roof structure. As a rough guide, allow around £800–£1,700 per square metre of new floor plus fixed costs for the staircase, steels and fees. Adding a shower room is the most common extra. We confirm a fixed price after surveying your loft.
Can you combine a loft conversion with other work?
Yes. Because we manage several trades under one contract, we can plan a loft conversion alongside other work on your Portsmouth home, such as new windows with rendering, or a kitchen refit with an extension. Combining jobs can reduce repeat set-up such as scaffolding, skips and access, and every element is listed and priced in the same written quote.
Can we stay at home during a loft conversion?
Most people stay at home during a loft conversion, because much of the work happens from scaffolding outside and the roof is opened up from above. The most disruptive point is near the end, when we break through the ceiling to fit the new staircase, which usually takes a few days. We put up dust screens on the landing and plan noisy work for reasonable hours.
Can I put a bathroom in my loft?
A bathroom or shower room can usually be added in a loft conversion if waste pipes can reach the soil stack with enough fall, or a pumped system can be used. Dormers make this easier because they give standing height for a shower. Water pressure, extraction and the position of the boiler also matter. We plan the bathroom layout at the design stage so pipes are hidden in the structure.
Also covering areas around Portsmouth
If your address falls within PO1, PO2, PO3 and PO4, we cover it. The same goes for neighbouring Southsea, Gosport and Fareham, which we include alongside Portsmouth when arranging surveys and quotes.