Extensions & Conversions

Single-storey extensions typically cost £1,500-£2,500 per m². A loft conversion ranges from £20,000-£60,000 depending on type.

Many extensions fall under permitted development. Loft conversions and larger extensions usually require planning permission.

A single-storey extension takes 3-4 months. Loft conversions take 6-8 weeks. Double-storey extensions take 4-6 months.

If your extension is built on or near a shared boundary wall, you must serve a Party Wall Notice to your neighbours under the Party Wall Act 1996. This typically costs £700-£1,000 per neighbour for a surveyor.

Velux/rooflight conversions are cheapest (£20,000-£35,000) but offer less headroom. Dormer conversions (£30,000-£50,000) add more space. Mansard conversions (£45,000-£65,000) maximise space but usually require planning permission.

A well-designed extension can add 10-20% to your property value. Loft conversions typically add 10-15%, single-storey extensions 5-10%, and double-storey extensions 15-20%. The added value usually exceeds the build cost.

Yes, all extensions and conversions require Building Regulations approval. This covers structural integrity, fire safety, insulation, ventilation, and drainage. Your builder or architect can manage the application process.

Usually yes, though there will be disruption. Single-storey rear extensions have minimal impact on daily life. Loft conversions may temporarily affect upstairs rooms. Your builder can advise on the best approach to minimise disruption.