What is a dormer loft conversion?

A dormer loft conversion adds a box-shaped structure to the rear roof slope, creating vertical walls and full headroom across most of the new room. It is the most common loft conversion in the UK because it works on terraced, semi-detached and detached houses.
How much does a dormer loft conversion cost in Strabane?
In Strabane, a dormer loft conversion typically costs £41,500–£58,500 for a typical rear dormer with en-suite, including VAT at 20% (standard rate). We start from a UK-wide guide and adjust it for Northern Ireland, where labour and materials are typically about 14% below average. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| A typical rear dormer with en-suite | £41,500–£58,500 |
| Higher specification | £58,500–£73,000 |
The main things that change the cost:
- Built-in storage and finishes
- Fire safety upgrades to the existing house
- Scaffolding and access
- Staircase position
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 dormer loft conversion in Strabane?
Here is how the rules work for a dormer loft conversion in Northern Ireland. In Northern Ireland a rear dormer can be permitted development if it does not face a road, sits no higher than the ridge and is set back at least 0.5 metres from the ridge, eaves, party wall and verges. Roof enlargements are not permitted development in conservation areas.
Northern Ireland has no Party Wall Act. Work on shared walls relies on agreement with the neighbour and common law, so we agree the arrangements in writing before work starts.
If the answer is not clear-cut, we can apply for formal confirmation before you commit to the build.
What we handle
The work we manage on a dormer loft conversion:
- Written agreement with neighbours on shared walls
- Building control completion certificate
- New staircase and fire-safe escape route
- Drawings and structural calculations
- Insulation, plastering, electrics and plumbing
- Steel beams and new floor joists
How long does it take?
Expect 6 to 9 weeks on site. Design and approvals come first and typically take 6 to 12 weeks, depending on the approval route.
Building in Strabane
Northern Ireland has many detached and semi-detached homes on generous plots, which suits single-storey rear extensions and garage conversions.
Projects in Strabane (BT82) are surveyed in person before we quote, so the price reflects your actual property.
How it works
- 01
Survey and brief
We visit, discuss your ideas and budget, and survey the property or site at no cost.
- 02
Drawings and written quote
We prepare the design and give you a written, itemised quote with inclusions and exclusions.
- 03
Approvals in place
We handle planning, building control and neighbour notices before work starts.
- 04
Build and handover
Work follows the agreed programme, with inspections along the way and a completion certificate at the end.
Questions about dormer loft conversions in Strabane
How much head height do I need?
Ideally at least 2.2 metres from the top of the ceiling joists to the underside of the ridge. Less can still work with a dormer, but we check this at the survey.
How long does it take?
Usually 6 to 9 weeks on site.
How much does a dormer loft conversion cost in Strabane?
In Strabane, a dormer loft conversion typically costs £41,500–£58,500 for a typical rear dormer with en-suite, including VAT at 20% (standard rate). Your fixed price depends on the survey and drawings.
Who approves a dormer loft conversion in Strabane?
Planning matters in Strabane go to the council covering your address, and the work needs building control approval. We prepare and submit the applications for you.
Do I need planning permission for a dormer loft conversion in Strabane?
In Northern Ireland a rear dormer can be permitted development if it does not face a road, sits no higher than the ridge and is set back at least 0.5 metres from the ridge, eaves, party wall and verges. Roof enlargements are not permitted development in conservation areas.
What fire safety is required?
Building regulations require a safe escape route. Converting a two-storey house to three storeys usually means a protected stairway with fire doors to habitable rooms and mains-wired smoke alarms.
