What is a rooflight loft conversion?
A rooflight loft conversion (sometimes called a roof window conversion) keeps the existing roof shape and adds roof windows that sit flush with the slope. The floor is strengthened, a staircase is added and the space is insulated and finished.
How much does a rooflight loft conversion cost in Trowbridge?
In Trowbridge, a rooflight loft conversion typically costs £30,500–£46,000 for a typical rooflight conversion, including VAT at 20% (standard rate). Prices in the South West sit near the national average for this kind of work, and the range for Trowbridge reflects that. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| A typical rooflight conversion | £30,500–£46,000 |
| Higher specification | £46,000–£57,500 |
Your quote will depend mainly on:
- Fire safety upgrades
- Bathroom or not
- Storage and finishes
- Floor and roof strengthening
A guide range is only a starting point: the guide price tool gives an instant figure for your size, and a free survey turns it into a fixed quote.
Do you need planning permission for a rooflight loft conversion in Trowbridge?
The approval route for Trowbridge is set by planning law in England. In England roof windows are permitted development if they project no more than 15 centimetres from the roof slope and side-facing windows are obscure-glazed. Listed buildings need consent.
Building regulations approval comes from the council’s building control service or a registered building control approver. The work is inspected at key stages, such as foundations, drainage and insulation, and a completion certificate is issued at the end.
At the survey we check your house’s planning history and any restrictions, and tell you which route applies.
What we handle
On a typical rooflight loft conversion we handle:
- Floor joists and any steel beams
- Building control sign-off
- Electrics, heating and plastering
- Head-height survey
- Insulation between and under rafters
- Staircase and fire-safe escape route
How long does it take?
The build itself usually takes 4 to 6 weeks on site. Design and approvals come first and typically take 6 to 12 weeks, depending on the approval route.
Building in Trowbridge
In parts of the South West, protected landscapes and conservation areas shape what can be built, so materials and roof forms are chosen carefully.
From BA14 outwards, we take on projects throughout Trowbridge and the surrounding parts of Wiltshire.
How it works
- 01
Survey and brief
We visit, discuss your ideas and budget, and survey the property or site at no cost.
- 02
Design and pricing
Design options, then a fixed quote based on the chosen drawings and specification.
- 03
Approvals
Planning or permitted development confirmation, building regulations and any party wall matters.
- 04
Build and sign-off
We run the build to a written programme and hand over the completion certificate.
Questions about rooflight loft conversions in Trowbridge
Is it cheaper than a dormer?
Yes, usually, because the roof shape stays the same. But you gain less full-height floor space.
Can I have a bathroom?
Yes, where there is enough head height at the shower or bath position.
How much head height do I need?
Around 2.2 metres or more from the top of the ceiling joists to the ridge is a good starting point. Insulation and new floor joists reduce the height.
How much does a rooflight loft conversion cost in Trowbridge?
In Trowbridge, a rooflight loft conversion typically costs £30,500–£46,000 for a typical rooflight conversion, including VAT at 20% (standard rate). Your fixed price depends on the survey and drawings.
Do you build rooflight loft conversions in Trowbridge?
Yes. We build rooflight loft conversions across Trowbridge, including postcodes BA14. Every project starts with a free home visit.