What is a basement conversion?
A basement conversion turns an existing cellar into living space, or excavates a new basement under the house or garden. Waterproofing, structural support and daylight are the main design challenges.
How much does a basement conversion cost in Omagh?
In Omagh, a basement conversion typically costs £1,650–£2,750 per m² for converting an existing cellar, including VAT at 20% (standard rate). For a typical 30 m² project that is roughly £49,500–£82,500. Building costs in Northern Ireland run about 14% below the UK average, and the figures for Omagh are adjusted to reflect that. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (21 m²) | £34,500–£58,000 |
| Typical project (30 m²) | £49,500–£82,500 |
| Larger project (42 m²) | £69,500–£115,500 |
| Rate per m² | £1,650–£2,750 |
The main things that change the cost:
- Ground water and access
- Existing cellar or new excavation
- Floor lowering and underpinning
- Agreements with neighbours on shared walls
Use the guide price tool to see how size and specification change the figure, then ask for a written, itemised quote.
Do you need planning permission for a basement conversion in Omagh?
Here is how the rules work for a basement conversion in Northern Ireland. In Northern Ireland converting an existing cellar usually does not need planning permission; new excavation and external changes may.
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.
Our first visit includes a check of your planning history, so you know the route before paying for drawings.
What we handle
The work we manage on a basement conversion:
- Lightwells and windows
- Electrics, heating and plastering
- Building control sign-off
- Waterproofing design (tanking or cavity drain membrane)
- Insulation, ventilation and drainage pumps
- Structural and ground survey
How long does it take?
The build itself usually takes 8 to 16 weeks for a cellar conversion; longer for new excavation. Design and approvals come first and typically take 3 to 5 months, depending on the approval route.
Building in Omagh
Across Northern Ireland, bungalows and chalet bungalows are common, so loft conversions and rear extensions are popular projects.
Projects in Omagh (BT78 and BT79) are surveyed in person before we quote, so the price reflects your actual property.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 02
Design and fixed quote
Drawings, structural calculations and an itemised, fixed price for the agreed specification.
- 03
Permissions sorted
Applications, building control and neighbour arrangements, all before the start date.
- 04
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about basement conversions in Omagh
Do I need planning permission for a basement conversion in Omagh?
In Northern Ireland converting an existing cellar usually does not need planning permission; new excavation and external changes may.
Is new excavation worth it?
It can be in high-value areas, but costs are high. We give a feasibility view before design starts.
How much does a basement conversion cost in Omagh?
In Omagh, a basement conversion typically costs £1,650–£2,750 per m² for converting an existing cellar, including VAT at 20% (standard rate). A typical 30 m² project comes to roughly £49,500–£82,500. Your fixed price depends on the survey and drawings.
How do you keep a basement dry?
With a waterproofing system designed to BS 8102, typically a cavity drain membrane with a sump pump, or a tanking system.
How long does a basement conversion take in Omagh?
Typically 8 to 16 weeks for a cellar conversion; longer for new excavation. Design and approvals beforehand usually take 3 to 5 months.
Can a basement be a bedroom?
Yes, with a suitable escape route such as a lightwell window or protected stair.