Tools · Cost index
Cost build-ups
A price is an argument, not a fact. These four take the jobs people price most often and set out what is actually in the number: materials, trade labour, and the fees and prelims that quotes leave for later. Every line carries the guide the figure came from, so you can check any of it.
Loft Conversion: Materials & Labour Build-Up
£45,000–£65,000
Rear dormer conversion on a 3-bed semi, one bedroom + en-suite, ~25 m² of floor
Ground Floor Extension: Materials & Labour Build-Up
£36,000–£56,000
Single-storey rear extension, 20 m² (5 m × 4 m), open-plan kitchen-diner with bifolds
Double Storey Extension: Materials & Labour Build-Up
£80,000–£120,000
Two-storey rear extension, 25 m² footprint (50 m² total), kitchen-diner below, bedroom + bathroom above
Internal Renovation: Materials & Labour Build-Up
£62,000–£122,000
Mid-spec refurbishment of a 3-bed, 90 m² house, rewire, replumb, new kitchen & bathroom, replaster & redecorate throughout
Figures are 2026 UK typical ranges, outside London unless a line says otherwise, and each page will re-price itself for your city. For a single item rather than a whole job, the cost index lists 81 of them; to put your own numbers against these, use the estimate builder.