Method

How Estiquote estimates work

Every Estiquote range comes from one published cost model. The website calculator and the iPhone app use the same 2026 prices. For now the website has more detailed fees for Scotland, Wales and Northern Ireland, and prices a few projects the app does not yet cover.

Model version 2026-Q3 · Reviewed 25 September 2026 · Next review December 2026 · Updated 22 October 2026

1. A base range for each project

For each project type and finish we set a planning range for a typical UK home outside London. We build it from published 2026 cost guides, prefer sources that state their basis and date, and cross-check at least two where we can. Where a source copies another, we count it once.

2. Size

Extensions, renovations and new builds are priced per square metre, with a small uplift for very small extensions because fixed costs do not shrink. Loft conversions are priced for about 30 m² and scale less than proportionally. Kitchens use small, medium and large; rewires, roofs and heat pumps use property size.

3. Region

We apply a regional factor from 0.82 (Northern Ireland) to 1.35 (London). No complete public set of factors exists, so ours is a synthesis of published regional comparisons, which we name below. Kitchens, bathrooms, boilers and windows use only part of the factor, because fitted products cost much the same across the UK.

4. VAT

Work on existing homes is standard-rated at 20%; new homes are zero-rated; homes empty for two years or more can qualify for 5%; heat pumps are zero-rated until 31 March 2027 (VAT Notice 708, Notice 708/6). Prices show VAT by default; trades can switch it off.

5. Fees and contingency

Design, engineering, building control, planning and party wall fees are shown separately, from published guides and our own survey of 91 councils. The planning figure is the England householder fee of £548 from 1 April 2026. We add a 15% contingency as a planning allowance, not a cost.

6. Updates

We review the model every quarter and date every change. Building costs rose by about 3% in the year to mid-2026 (BCIS), so older figures age quickly.

Assumptions

Figures are planning ranges built from published 2026 UK cost guides and industry indices, not quotes.
Extension, loft, garage, renovation and knock-through figures are treated as excluding VAT; kitchen, bathroom, rewire, roof, boiler and window figures are treated as prices paid, which include VAT.
Regional factors are Estiquote's synthesis of published regional comparisons (FMB, Checkatrade, Build It, Homebuilding & Renovating, MyJobQuote, NI Trades); no complete public set exists.
Material-heavy projects (kitchens, bathrooms, boilers, windows) apply only part of the regional factor, because fitted products cost much the same across the UK.
Extensions smaller than the stated threshold carry a small-size uplift, because fixed costs do not shrink with floor area.
Loft conversion totals are for about 30 m² of new floor area and scale less than proportionally with size.
Contingency of 15% is a planning allowance, not a cost.

Limits

These are planning ranges, not quotes or surveys. They do not know your site, your access, your ground or your design. Always get at least three detailed written quotes.

Sources

Download the full model: uk-rates.json.