Single Storey Extension Cost in Lancashire: 2025 Price Guide

Single storey extensions are one of the most popular home improvement projects in east and central Lancashire — and one of the most searched for. This guide gives you realistic cost figures for 2025, explains what affects the price, and tells you what to look for in a quote.

Typical Single Storey Extension Costs in Lancashire (2025)

Extension costs are usually quoted per square metre of internal floor area. Current rates for a single storey rear extension in east Lancashire:

- **Standard specification:** £1,800–£2,400 per m² - **Mid-range specification:** £2,400–£3,000 per m² - **High specification:** £3,000–£3,800 per m²

For a typical 20 m² kitchen extension:

| Specification | Estimated Total | |---|---| | Standard | £36,000–£48,000 | | Mid-range | £48,000–£60,000 | | High spec | £60,000–£76,000 |

For a smaller 12 m² utility room or dining room:

| Specification | Estimated Total | |---|---| | Standard | £21,600–£28,800 | | Mid-range | £28,800–£36,000 |

These figures include structural work, roofing, insulation, internal plastering, electrics, and an externally rendered finish that matches your existing property.

What Affects the Cost?

Size and shape Larger extensions cost more overall but less per m², since the fixed costs (foundations, structural calculations, scaffolding) are spread across a larger floor area. L-shaped or complex-plan extensions cost more per m² than simple rectangular designs.

Specification The biggest variable in cost is what goes inside: flooring, windows, doors, rooflights, kitchen fittings (if a kitchen extension), and the level of internal finish. A basic shell-and-plaster finish is much less expensive than a fully fitted kitchen with underfloor heating and Velux rooflights.

Ground conditions Poor ground conditions — particularly in older Lancashire towns where made ground, former industrial use, or high water tables are common — can require deeper or more expensive foundations. This is assessed at the survey stage.

Planning and structural engineering fees Planning applications (where required) cost around £250 for the application fee. Structural engineer's drawings typically add £800–£1,500 depending on complexity. We coordinate both on your behalf.

VAT Extensions are subject to full 20% VAT. This is a meaningful addition — always confirm whether quotes include VAT before comparing them.

What's Included in a Cooke Rendering Quote

Our extension quotes include:

- Full structural and building work (foundations, blockwork, roofing, insulation) - External rendered finish matching the existing property - Internal plaster skim ready for decorating - Electrics first and second fix (light points and sockets) - All relevant building regulation submissions and inspections - Site management and clean-up

What isn't included as standard: kitchen or bathroom fitting, floor finishes, internal decoration, and bespoke glazing. We can include these by arrangement.

Permitted Development vs Planning Permission

Many single storey rear extensions can be built under Permitted Development rights — meaning no formal planning application is required. Broadly, you can extend:

- Up to 4 metres from the rear wall (3 metres for terraced/semi-detached) without prior approval - Up to 8 metres (6 metres for terraced/semi-detached) under the Prior Approval notification process - Up to 4 metres in height at the ridge

The actual rules are more detailed and depend on your specific property. We assess Permitted Development eligibility at survey stage and manage any notifications or applications on your behalf.

Is an Extension Worth It?

In most cases, yes. In Lancashire's current property market, a well-executed single storey extension typically adds more to property value than it costs to build. A 20 m² extension in a mid-range area of Burnley or Accrington can add £40,000–£60,000 in value — more than the construction cost in most scenarios.

Beyond value, the quality-of-life improvement is significant. If your family has outgrown your home but the cost and disruption of moving is daunting, extending is almost always the more cost-effective choice.

Call 07900 926987 to arrange a free site visit and detailed quote for your extension project.