What is a mansard loft conversion?

A mansard loft conversion rebuilds the roof with a nearly vertical slope (about 72 degrees) and a flat top, effectively adding a new storey. Small dormer windows sit within the steep slope. Mansards are common on period terraces in towns and cities.
How much does a mansard loft conversion cost in Newry?
In Newry, a mansard loft conversion typically costs £56,000–£81,500 for a typical rear mansard, including VAT at 20% (standard rate). Prices across Northern Ireland are typically 14% below the UK average for this kind of work, which is reflected in the range for Newry. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| A typical rear mansard | £56,000–£81,500 |
| Higher specification | £81,500–£102,000 |
The biggest cost drivers are:
- Scaffolding on busy streets
- Agreements with neighbours on shared walls
- Roof covering: natural slate costs more
- Number of dormers and lead work
For a figure based on your own measurements, try the guide price tool, then book a free home visit for a fixed quote.
Do you need planning permission for a mansard loft conversion in Newry?
Before anything is built in Newry, we confirm which approvals apply in Northern Ireland. In Northern Ireland a mansard needs planning permission from the council.
In Northern Ireland building control approval comes from the council, usually through a full plans application or a building notice, with inspections during the work and a completion certificate at the end.
Our first visit includes a check of your planning history, so you know the route before paying for drawings.
What we handle
On a typical mansard loft conversion we handle:
- Planning drawings and application
- Structural design and calculations
- Dormer windows
- Staircase and fire-safe escape route
- Insulation, electrics, plumbing and plastering
- Written agreement with neighbours on shared walls
How long does it take?
Expect 9 to 12 weeks on site, after planning approval. Design and approvals come first and typically take 3 to 4 months, depending on the approval route.
Building in Newry
Across Northern Ireland, bungalows and chalet bungalows are common, so loft conversions and rear extensions are popular projects.
If your home is in Newry or close by in Banbridge, Portadown and Armagh, a free home visit is the first step.
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
Planning or permitted development confirmation, building regulations and any party wall matters.
- 04
Build and handover
Work follows the agreed programme, with inspections along the way and a completion certificate at the end.
Questions about mansard loft conversions in Newry
What roof covering is used?
Natural slate is traditional; some councils accept other materials. We follow local guidance.
How much does a mansard loft conversion cost in Newry?
In Newry, a mansard loft conversion typically costs £56,000–£81,500 for a typical rear mansard, including VAT at 20% (standard rate). Your fixed price depends on the survey and drawings.
Why choose a mansard over a dormer?
A mansard gives more usable floor space and a neater appearance from the street, but costs more and needs planning permission.
How long does a mansard loft conversion take in Newry?
Typically 9 to 12 weeks on site, after planning approval. Design and approvals beforehand usually take 3 to 4 months.
Can I stay at home?
Usually. The new roof is built under a temporary cover so the house stays dry.
Do I need planning permission for a mansard loft conversion in Newry?
In Northern Ireland a mansard needs planning permission from the council.
