A loft conversion is one of the most popular ways to add a bedroom or home office without losing garden space. This guide explains the main types, what they typically cost, and what to check before you start.
Costs below are typical UK ranges for the building work and will vary with region, property type and specification. They are guides rather than quotes.
First: is your loft suitable?
Most conversions need enough height at the highest point, commonly around 2.2 metres from floor to ridge, and a roof structure that can be adapted. Things that affect suitability include:
- the roof type and pitch (steeper roofs give more headroom)
- the existing structure: older cut roofs and modern trussed roofs are converted differently
- water tanks, chimneys and pipework that may need moving
- staircase position: you need room for a safe stair that meets building regulations
- fire escape requirements for the new floor
A survey by a builder or structural engineer will confirm whether your loft is a good candidate.
The main types of loft conversion
Rooflight (Velux) conversion
Rooflight windows are fitted into the existing roof slope with no change to the roof shape. This is the simplest and usually cheapest option, but it needs plenty of existing headroom. Typical cost: roughly £20,000–£40,000.
Dormer conversion
A box-shaped extension projects from the roof slope to create more floor area and standing room. It is the most common choice for terraced and semi-detached houses. Typical cost: roughly £35,000–£60,000.
Hip-to-gable conversion
On a house with a sloping side roof (a hip), the side is built up vertically into a gable wall to gain floor space. It suits detached and semi-detached homes and is often combined with a rear dormer. Typical cost: roughly £40,000–£70,000.
Mansard conversion
A mansard changes the roof shape to a near-vertical rear slope, giving the most space. It usually needs planning permission and is common in terraced streets. Typical cost: roughly £50,000–£80,000 or more.
Planning permission
Many loft conversions can be done under permitted development, with limits on the volume added to the roof (commonly 40 m³ for terraced and 50 m³ for other houses), no extension beyond the front roof slope, restrictions on materials, balconies and side windows, and tighter rules in conservation areas. Flats and some designated areas need permission, and Welsh rules can differ from English ones, so confirm with Newport City Council. See our full guide to planning permission for extensions.
Building regulations always apply
Even when planning is not needed, a loft conversion must comply with building regulations, covering:
- structural strength of floor and roof alterations
- fire safety: protected escape route, fire doors and interlinked smoke alarms
- insulation and ventilation
- stairs, headroom and electrics
See building regulations for house extensions.
Party walls
If you live in a semi-detached or terraced house, work to the shared wall (for example, steel beams resting on it) usually falls under the Party Wall etc. Act 1996. Read our party wall guide.
How long does it take?
A typical loft conversion takes around 6–10 weeks on site once design, approvals and any scaffolding are in place, although complex conversions take longer.
Loft conversion or extension?
If your loft is unsuitable or you want a larger family space, a ground-floor extension may suit better. Our house extension cost guide compares the numbers.
Planning a loft conversion in Newport?
Abron Contracting can assess your roof, explain the options and provide a written quotation. Contact us or call 01633379170.
Frequently asked questions
How much does a loft conversion cost in the UK?
Typical ranges are roughly £20,000–£40,000 for a rooflight conversion, £35,000–£60,000 for a dormer, £40,000–£70,000 for hip-to-gable and £50,000–£80,000 or more for a mansard. Your price depends on size, specification and location.
Do I need planning permission for a loft conversion?
Often not for rooflight and many dormer conversions that stay within permitted development limits, but you should confirm for your property, especially in conservation areas, flats and Wales.
How much headroom do I need?
Builders generally look for about 2.2 metres at the highest point, but lower roofs can sometimes be converted with a dormer or by altering the roof structure.
Does a loft conversion add value?
It can, particularly when it adds a bedroom and bathroom. The effect varies by area, so ask a local estate agent.
How long does a loft conversion take?
Around 6–10 weeks on site for a typical conversion, plus time for design and approvals beforehand.
