St Albans, Hertfordshire
Single Storey Extension in St Albans
A single storey rear or side extension is one of the most popular home improvements in the UK, adding valuable living space without the complexity of multi-level construction.
Estimated Cost
£35,000 – £55,000
Based on 20m² at local rates
8–14 weeks typical duration
Planning permission: Usually not required
Cost Breakdown for Single Storey Extension
Estimated costs for a typical 20m² single storey project, adjusted for local labour and material rates.
| Category | Low Estimate | High Estimate |
|---|---|---|
| Foundations & Groundworks | £4,200 | £6,600 |
| Structural Walls | £5,250 | £8,250 |
| Roof Structure & Covering | £3,500 | £5,500 |
| Windows & Doors | £2,800 | £4,400 |
| Plumbing & Drainage | £2,800 | £4,400 |
| Electrical Installation | £2,100 | £3,300 |
| Plastering & Rendering | £2,100 | £3,300 |
| Flooring | £1,750 | £2,750 |
| Kitchen/Bathroom Fitting | £3,500 | £5,500 |
| Decoration & Finishing | £1,750 | £2,750 |
| Professional Fees | £3,500 | £5,500 |
| Contingency (10%) | £1,750 | £2,750 |
| Total Estimated Cost | £35,000 | £55,000 |
* Costs are estimates based on regional averages and may vary depending on specification, access, and site conditions. Prices include VAT at 20%.
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