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 Coleraine?
In Coleraine, 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 Coleraine. 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 |
Your quote will depend mainly on:
- Scaffolding on busy streets
- Front, rear or both
- Number of dormers and lead work
- Agreements with neighbours on shared walls
Your exact price depends on the survey and drawings. The guide price tool gives a quick range in the meantime.
Do you need planning permission for a mansard loft conversion in Coleraine?
Approvals for a mansard loft conversion in Coleraine follow the rules for Northern Ireland. In Northern Ireland a mansard needs planning permission from the council.
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.
At the survey we check your house’s planning history and any restrictions, and tell you which route applies.
What we handle
What we take care of:
- Insulation, electrics, plumbing and plastering
- Written agreement with neighbours on shared walls
- New roof structure, slate or tile covering and lead work
- Planning drawings and application
- Structural design and calculations
- Building control sign-off
How long does it take?
Expect 9 to 12 weeks on site, after planning approval. Before that, surveys, drawings and approvals usually take 3 to 4 months, longer if the council asks for changes.
Building in Coleraine
Northern Ireland has many detached and semi-detached homes on generous plots, which suits single-storey rear extensions and garage conversions.
If your home is in Coleraine or close by in Limavady, Ballymena and Magherafelt, 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
Design and pricing
Design options, then a fixed quote based on the chosen drawings and specification.
- 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 mansard loft conversions in Coleraine
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.
What roof covering is used?
Natural slate is traditional; some councils accept other materials. We follow local guidance.
Who approves a mansard loft conversion in Coleraine?
Planning matters in Coleraine go to the council covering your address, and the work needs building control approval. We prepare and submit the applications for you.
Can I stay at home?
Usually. The new roof is built under a temporary cover so the house stays dry.
How much does a mansard loft conversion cost in Coleraine?
In Coleraine, 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.
Do I need planning permission for a mansard loft conversion in Coleraine?
In Northern Ireland a mansard needs planning permission from the council.