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 Derry?
In Derry, a structural alteration typically costs £3,750–£8,250 for a typical knock-through with steel beam, 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 Derry. 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:
- Span of the opening
- Agreements with neighbours on shared walls
- Flush or downstand beam
- Floor and ceiling repairs
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 structural alteration in Derry?
Whether you need planning permission depends on your house and its location in Northern Ireland. In Northern Ireland removing a load-bearing wall needs building control approval 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.
At the survey we check your house’s planning history and any restrictions, and tell you which route applies.
What we handle
The work we manage on a structural alteration:
- Fire protection to the steel
- Building control application
- Written agreement with neighbours on shared walls
- Steel beam supply and installation on padstones
- Making good, plastering and flooring repairs
- Temporary propping
How long does it take?
The build itself usually takes 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 Derry
Across Northern Ireland, bungalows and chalet bungalows are common, so loft conversions and rear extensions are popular projects.
Derry sits in County Londonderry. We cover the whole of Derry, including postcodes BT47.
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 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
Build and sign-off
We run the build to a written programme and hand over the completion certificate.
Questions about structural alterations in Derry
How long does a knock-through take?
Usually 1 to 2 weeks on site, plus a few days for plastering to dry.
Do I need planning permission for a structural alteration in Derry?
In Northern Ireland removing a load-bearing wall needs building control approval from the council.
How much does a structural alteration cost in Derry?
In Derry, 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 you build structural alterations in Derry?
Yes. We build structural alterations across Derry, including postcodes BT47. Every project starts with a free home visit.
How do I know if a wall is load-bearing?
Only a survey can confirm it. Walls that carry floor joists, roof loads or walls above are load-bearing. We check on site and the engineer confirms.
Do I need building regulations approval?
Yes. Removing a load-bearing wall is building work that needs approval, with calculations for the beam.