Home Extension Cost London 2026: How Much Does a Home Extension Cost?
- LCCL Construction
- 5 days ago
- 3 min read
The cost of a home extension in London depends on the type of extension, the size, the specification of finishes and the location within London. This guide gives you accurate 2026 home extension costs across all four extension types so you can budget realistically before starting your project. LCCL Construction has delivered hundreds of home extensions across London and Hertfordshire and provides fully transparent pricing as part of our complete design and build service.
Home Extension Cost by Type in London in 2026
Rear home extension cost: £35,000 to £75,000. The most popular extension type. Extends the ground floor at the back of the property. See our full rear extension guide.
Side return extension cost: £35,000 to £75,000. Fills the narrow side alley alongside a rear extension. See our full side return extension guide.
Wraparound extension cost: £60,000 to £110,000. Combines rear and side return for maximum ground floor space. See our full wraparound extension guide.
Double storey extension cost: £85,000 to £165,000. Adds space on both ground and first floors. See our full double storey extension guide.
What Is Included in a Home Extension Cost in London?
LCCL Construction's home extension costs include the full design and build service: measured building survey, architectural design, planning permission application where required, building regulations, structural engineer calculations, party wall notices and agreements where required, all construction works including groundworks, foundations, superstructure, roof, first and second fix, insulation, electrics, plumbing, plastering and finish. Kitchen units, appliances and bathroom fittings are typically supplied by the client on second fix.
What Factors Affect Home Extension Cost in London?
The key factors are: type of extension, size in square metres, number of rooms and bathrooms, specification of windows glazing and doors including bifolds or sliding doors, whether planning permission is required, complexity of groundworks and structural steelwork, location within London and quality of finishes. Premium London postcodes typically cost 10-20 per cent more than outer London due to higher labour costs and planning complexity.
Home Extension Cost Per Square Metre in London
Home extension costs in London typically range from £2,200 to £3,800 per square metre. A standard rear extension creating 20 square metres at £2,500 per square metre costs approximately £50,000. A premium wraparound in Central London creating 35 square metres at £3,500 per square metre costs approximately £122,500. Extensions are subject to 20 per cent VAT — unlike new build construction which is zero rated.
How Much Value Does a Home Extension Add?
A well-designed home extension in London typically adds 150 to 250 per cent of the construction cost in property value. A wraparound costing £80,000 typically adds £120,000 to £200,000 in value. See our full guide on how much value an extension adds.
Frequently Asked Questions About Home Extension Costs in London
How much does a home extension cost in London in 2026?
From £35,000 for a small rear extension to £165,000 for a large double storey. A typical wraparound costs £60,000 to £110,000.
Does the cost include planning permission?
Yes — LCCL Construction includes all planning permission costs and professional fees in the design and build estimate.
What is the cheapest type of home extension?
A single storey rear extension is the most cost effective way to add ground floor space starting from £35,000.
To get a free detailed estimate call LCCL Construction on 020 8037 7332 or get an instant quote online.
