How UK Home Renovation Costs Are Estimated

Summary

Estimating the cost of a UK home renovation depends on which projects you’re planning (kitchen, bathroom, loft conversion, extension, etc.), the quality of finishes you want, and where in the country you live. The calculator combines per-square-metre rates with fixed costs for each project type, then adjusts for quality level and regional labour costs.

It also estimates how much value each renovation adds to your property, helping you decide whether the investment makes financial sense — or whether it’s purely about lifestyle improvement.

How it works

Each renovation project has two cost components:

1. Variable cost — a per-square-metre rate for the build itself (materials, labour, finishes)
2. Fixed cost — one-off costs that don’t scale with room size (plumbing connections, appliances, building regulations, planning fees)

The total cost for each project is:

A contingency buffer (typically 10–15%) is then added to the total of all projects.

Quality levels

Regional multipliers

Based on UK labour rate data — London tradespeople charge 25–30% more than the national average, while Northern regions are 15–20% below average.

Value-add estimates

Each renovation type adds a percentage of the property’s current value. These are industry-wide averages — actual uplift depends on local market conditions, build quality, and the property’s current condition.

Worked example

Inputs explained

• Property value — current market value of the property, used to calculate value-add percentages
• Project toggles — enable/disable individual renovation projects (kitchen, bathroom, loft, extension, garage, boiler, glazing, redecoration)
• Project size — floor area in square metres for area-based projects; fixed-cost projects (boiler, glazing) don’t have a size input
• Quality level — budget, standard, or premium finishes
• Region — UK region, which adjusts costs based on local labour rates
• Contingency — percentage buffer for unexpected costs (recommended 10–15%)

Outputs explained

• Total renovation cost — sum of all project costs plus contingency buffer
• Cost breakdown — individual cost for each enabled project, sorted by cost
• Value added — estimated increase in property value from each renovation
• New property value — current value plus total value added
• ROI — return on investment: (value added - total cost) / total cost x 100
• Monthly cost — total cost divided by 12 months
• Verdict — colour-coded assessment based on overall ROI: excellent (20%+), good (0%+), caution (-30%+), poor (below -30%)

Assumptions & limitations

• Costs are UK 2025/26 averages derived from multiple industry sources (HomeOwners Alliance, Checkatrade, FMB, Beams Renovation). Actual quotes may vary significantly.
• The calculator uses a blended cost model (per-m² variable cost plus fixed cost) rather than pure per-m² pricing. This better reflects reality: a tiny bathroom still needs a toilet, sink, and plumbing regardless of size.
• Value-add percentages are national averages. Actual property value uplift depends heavily on local market conditions, the quality of work, and the property’s current condition.
• Loft conversion costs model a Velux/rooflight-type conversion. Dormer, hip-to-gable, and mansard conversions are significantly more expensive (£45k–£80k+ for 25m²).
• Extension costs model a single-storey rear extension including structural build. Professional fees (architect, structural engineer) are included in the fixed cost component.
• The calculator does not account for planning permission fees (£528 from April 2025) or building regulations fees (£200–£900), which are additional.
• No VAT modelling — costs are shown inclusive. Some energy-efficiency works may qualify for 0% or 5% VAT.

Verification