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.
Looking for a loft conversion in South Glamorgan? We organise the whole job, bringing in the trades it needs under one agreement, and you have a single contact. We cover Cardiff, Barry, Penarth and Llantwit Major, along with villages and suburbs nearby. The rules in Wales decide what consents are needed, and our guide range of £27,500–£60,000 including VAT gives you a realistic starting point for a budget.
- Guide price
- £27,500–£60,000 inc VAT
- Time on site
- 6–10 weeks on site
- Planning rules
- Wales
- Price level
- About 8% below the national guide
- Towns listed
- 4
- Survey
- Free, with a written quote
How much does a loft conversion cost in South Glamorgan?
The table below shows guide prices for a loft conversion in South Glamorgan. They are based on rates in Wales, which run about 8% below the national guide, giving an overall range of £27,500–£60,000. All figures include VAT and are firmed up after a free site survey.
| Type of job | What it usually involves | Guide in South Glamorgan |
|---|---|---|
| Rooflight conversion | Rooflights in the existing slope, a new floor, staircase and insulation, where head height already works. | £18,500–£32,000 |
| Dormer conversion | A rear dormer adding headroom and floor space, often with a bedroom and shower room. | £29,500–£55,000 |
| Hip-to-gable or mansard | Larger structural changes to the roof for the maximum usable space. | £46,000–£78,000 |
Your price depends mostly on:
- Conversion type: rooflight, dormer, hip-to-gable or mansard
- Floor area, existing head height and roof structure
- Adding a shower room or en-suite in the roof
- Staircase layout, fire doors and the level of finishes
What do you get?
- Structural calculations and steel beams where needed
- New floor joists strong enough for a habitable room
- Staircase designed to fit your landing and meet regulations
- Fire doors, mains-linked smoke alarms and a protected escape route
- Electrics, heating and plumbing by qualified trades, with certificates
- Plastering, internal doors and building control sign-off
Housing across South Glamorgan
Cardiff has large areas of bay-fronted Victorian and Edwardian terraces in districts such as Roath, Canton and Cathays, plus interwar suburbs, post-war estates and modern flats around Cardiff Bay. Penarth has Victorian villas, Barry mixes terraces with newer estates, and Vale of Glamorgan villages are often built of local limestone.
Terraces commonly suit loft conversions, side-return and rear extensions, and bay window renewal. Suburban semis take side extensions and driveways, and stone village homes need lime-based repairs.
Mild but wet, with coastal exposure along the Severn estuary and Bristol Channel affecting render, roofline and windows.
Do you need permission in South Glamorgan?
The notes below cover Wales, which is where South Glamorgan sits. Rules change and every property is different, so we speak to the council before pricing your job.
In Wales, loft conversions and dormers can be permitted development within volume and position limits (for example, dormers on rear-facing slopes and set back from the eaves). Conservation areas and listed buildings need planning permission.
Building Regulations approval is needed in Wales, and the Party Wall etc. Act 1996 applies to work on shared walls.
Rules change and every property is different, so we check the planning history and constraints for your address before we quote.
The four stages
A visit to your home
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.
Your fixed price
After the survey we send a quote for a loft conversion that fixes the price for the scope we've agreed. If you want to change materials or scope, we revise it in writing before anything is booked.
Plan and prepare
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.
Finish and handover
The work is carried out to the agreed specification, with floors and furniture protected and the site kept tidy. At the end we clean up, walk through the finished job with you and hand over any certificates.
What you can expect from us
Questions about a loft conversion in South Glamorgan
Do you cover Cardiff, Barry and Penarth?
Yes. As well as South Glamorgan, we cover Cardiff, Barry and Penarth and the rest of South Glamorgan. Our coverage is UK-wide, so the process is the same wherever you are: a free site survey, a quote in writing that fixes the price for the agreed scope, and one point of contact while the work is planned and carried out.
What fire safety measures does a loft conversion need?
A loft conversion needs a safe way out in a fire, because the new room is high above the ground. This usually means a protected stair route down to an exit, with fire doors onto the stairway, mains-linked smoke alarms on each floor and sometimes an escape window. The exact approach depends on your house layout. Building control checks these measures before signing off the work.
Do I need planning permission for a loft conversion?
Whether a loft conversion needs planning permission depends on its size and design, your home's location, whether it is listed or in a conservation area, and which UK nation you live in. In England, many conversions fall under permitted development if the added volume is within 40m³ for terraced houses or 50m³ for other houses and nothing extends beyond the front roof slope. We check what applies before quoting.
Who do I deal with during the job?
One point of contact manages your project from survey to handover. They schedule the trades working under our contract, keep you updated on progress, and are the person to call with any question. You don't need to coordinate builders, electricians or decorators separately, because that is part of what we do.
Does the Party Wall Act apply to a loft conversion?
The Party Wall etc. Act 1996 applies in England and Wales only, and loft conversions on terraced and semi-detached houses often fall within it, because steel beams are usually set into the shared wall. You must serve notice on the neighbour before work starts, and they can agree or appoint a surveyor. Scotland and Northern Ireland have no equivalent Act. We tell you during the survey whether notices are likely.
Towns in South Glamorgan
Below is our list of South Glamorgan towns for a loft conversion. If yours isn't shown, we may still cover it, so it is worth asking us directly.