What is a structural alteration?
A structural alteration changes how a house carries its loads, most often by removing a load-bearing wall and replacing it with a steel beam. It is how kitchens and dining rooms become open-plan, and how extensions are joined to the original house.
How much does a structural alteration cost in County Londonderry?
In County Londonderry, a structural alteration typically costs £3,750–£8,250 for a typical knock-through with steel beam, including VAT at 20% (standard rate). That range is adjusted for Northern Ireland, where domestic building work typically costs around 14% below the national average. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| A typical knock-through with steel beam | £3,750–£8,250 |
| Higher specification | £8,250–£10,500 |
The biggest cost drivers are:
- Agreements with neighbours on shared walls
- Flush or downstand beam
- What sits above the wall
- Span of the opening
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 structural alteration in County Londonderry?
The approval route for County Londonderry is set by planning law in Northern Ireland. In Northern Ireland removing a load-bearing wall needs building control approval 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.
If the answer is not clear-cut, we can apply for formal confirmation before you commit to the build.
What we handle
From survey to sign-off, the job normally involves:
- Making good, plastering and flooring repairs
- Building control application
- Steel beam supply and installation on padstones
- Structural engineer’s calculations and drawings
- Written agreement with neighbours on shared walls
- Temporary propping
How long does it take?
Build time is typically 1 to 2 weeks on site for a typical knock-through. Design and approvals come first and typically take 6 to 12 weeks, depending on the approval route.
Building in County Londonderry
Across Northern Ireland, bungalows and chalet bungalows are common, so loft conversions and rear extensions are popular projects.
Towns we cover in County Londonderry include Derry, Coleraine, Limavady and Magherafelt.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 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
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about structural alterations in County Londonderry
How much does a structural alteration cost in County Londonderry?
In County Londonderry, a structural alteration typically costs £3,750–£8,250 for a typical knock-through with steel beam, including VAT at 20% (standard rate). Your fixed price depends on the survey and drawings.
Do I need building regulations approval?
Yes. Removing a load-bearing wall is building work that needs approval, with calculations for the beam.
Do you build structural alterations in County Londonderry?
Yes. We build structural alterations across County Londonderry, including postcodes BT28, BT45, BT46, BT47 and BT48. Every project starts with a free home visit.
Can the beam be hidden?
Often, by setting it within the ceiling depth. It depends on the joists and span.
Do I need planning permission for a structural alteration in County Londonderry?
In Northern Ireland removing a load-bearing wall needs building control approval from the council.
How long does a knock-through take?
Usually 1 to 2 weeks on site, plus a few days for plastering to dry.