Extensions

A plain-English comparison of the main ways UK homeowners pay for an extension or loft conversion in 2026, with current rates, costs and risks.

What a side extension on a semi-detached or detached house costs in 2026, from single storey kitchen and utility extensions to two storey builds over a garage.

What it costs to extend at the back of your house in 2026, priced by depth and width, with the planning route, steelwork, drains and party wall costs each option brings.

A 2026 guide to lean-to conservatory prices in the UK, from small 2.5m × 2m kits to 4m × 3.5m solid-roof builds, with planning and building regs explained.

What it costs to replace a conservatory roof in 2026, from a like-for-like polycarbonate swap to a lightweight tiled roof, with size, style and regional prices.

What it costs to convert an existing cellar or dig a new basement in 2026, including waterproofing, underpinning, party wall and London planning rules.

What a front porch costs in the UK in 2026, from a simple canopy to a brick-built porch, plus the permitted development and building regulations rules.

What a flat roof extension costs in 2026, plus how EPDM, GRP and felt roofs compare on price and lifespan.

What a wrap around (L-shaped) extension costs in 2026, with prices by size, spec and region, a full fee breakdown and the planning rules that usually apply.

How much a side return or side infill extension costs in 2026, with London and regional prices, steel and glazing costs, party wall fees and planning rules.