Extension Loft Price Index
For rooflight, the median published figure in the Extension Loft Price Index is 32,500 GBP across 6 figures from the sources' own pages (range 18,000 to 55,000 GBP), read 12 October 2026.
- 47,500 to 23,750
- 523,750 to 40,000
- 1740,000 to 56,250
- 456,250 to 72,500
- 272,500 to 88,750
- 288,750 to 105,000
Bands
| Bucket | Value |
|---|---|
| 7,500 to 23,750 | 4 figures |
| 23,750 to 40,000 | 5 figures |
| 40,000 to 56,250 | 17 figures |
| 56,250 to 72,500 | 4 figures |
| 72,500 to 88,750 | 2 figures |
| 88,750 to 105,000 | 2 figures |
25 of the 32 named sources read in full publish a figure; 7 publish none, read 12 October 2026.
By type
| Breakdown | Median | Range | Sources |
|---|---|---|---|
| typeconservatory | 27,000GBP | 27,000 to 27,000GBP | 1 |
| typedormer | 42,500GBP | 30,000 to 55,000GBP | 6 |
| typehip-to-gable | 55,000GBP | 45,000 to 55,000GBP | 3 |
| typerooflight | 32,500GBP | 18,000 to 55,000GBP | 6 |
| typeL-shaped dormer | 62,500GBP | 60,000 to 65,000GBP | 2 |
| typemansard | 50,000GBP | 45,000 to 60,000GBP | 5 |
| typesingle-storey extension | 55,000GBP | 55,000 to 55,000GBP | 1 |
| typekitchen extension | 71,400GBP | 50,000 to 75,000GBP | 3 |
| typedouble-storey extension | 102,500GBP | 100,000 to 105,000GBP | 2 |
| typegarage conversion | 10,000GBP | 7,500 to 20,000GBP | 3 |
Every figure, with its source
One row per published figure: the figure as the source's own page publishes it, the page, and the day it was read. A figure that is not on a page we read is not on this one.
The sentence each figure was read from (34)
- JD Building London extension costs, read 2026-10-12:
Our analysis suggests that the estimated cost of 2 storey extension London 2026 projects starts at approximately £105,000.
- Arkiplan two-storey extension cost, read 2026-10-12:
Planning and regulations: Permits, structural engineering, and building control add time and expense. If you’re considering a two storey side extension, note that these tend to have specific costs related to the footprint and integration with your existing structure, often falling between £100,000 and £140,000 depending on size and finish.
- Resi construction and extension cost guide, read 2026-10-12:
Building an extension or conversion in the UK typically costs between £75,000 and £150,000, depending on size, quality, and location, with prices often around £1500 per square metre for new builds and £800 for refurbishments, excluding VAT.
- Mayfair Studio kitchen extension London, read 2026-10-12:
Kitchen extensions cost £75k-120k in London (structure + kitchen + fees).
- Beams kitchen extension cost, read 2026-10-12:
KitchensPlanning and budgeting A kitchen extension costs £71,400 to £103,000 including VAT across most of the UK for a 20 square metre single-storey build, or £90,400 to £144,000 in London.
- Lawsons Lofts loft conversion costs, read 2026-10-12:
From £65,000 L Shaped Dormer
- Touchstone Lofts pricing, read 2026-10-12:
L-shaped dormer loft conversions – from £60,000
- Touchstone Lofts pricing, read 2026-10-12:
Mansard dormer loft conversions – from £60,000
- Touchstone Lofts pricing, read 2026-10-12:
Hip to gable loft conversions – from £55,000
- Advance Architecture London loft conversion price guide, read 2026-10-12:
Architect-led budgets: Provide a holistic view including design, structural engineering, and planning compliance. 2026 Minimums: Expect a £55,000 entry point for a simple Velux conversion in most London boroughs.
- Build Team extension cost, read 2026-10-12:
A small extension of 10 to 15 m² costs from around £55,000 to £95,000 all-in in 2026, depending on specification and glazing.
- Lawsons Lofts loft conversion costs, read 2026-10-12:
From £55,000 Hip to Gable
- Excellence Living Bristol loft conversion cost, read 2026-10-12:
Loft conversion cost starts from £40,000 for a rooflight conversion and £55,000 for a dormer or hip to gable conversion.
- Loft Conversion UK mansard page, read 2026-10-12:
A mansard loft conversion is the most expensive type of loft conversion with costs across the UK ranging from £55,000 to £95,000 on average in 2026.
- Touchstone Lofts pricing, read 2026-10-12:
Dormer loft conversions – from £50,000
- Home Conversion Scotland loft conversion Glasgow, read 2026-10-12:
The cost for Mansard loft conversions varies from as high as £50,000 to £70,000.
- NGC Build kitchen extension cost London, read 2026-10-12:
A 20m² extension in London could cost between £50,000 and £90,000, while a 40m² project might run from £100,000 to £180,000.
- SPS Roofing mansard loft conversion cost, read 2026-10-12:
The larger the loft, the more materials and labor will be required, and the higher the cost will be. On average, the cost of a mansard loft conversion is around £50,000.
- Lawsons Lofts loft conversion costs, read 2026-10-12:
From £45,000 Rear Dormer
- Extension Architecture mansard cost guide, read 2026-10-12:
In general, a Mansard loft conversion costs between £45,000 to £70,000 and you can use our house extension cost calculator for estimated prices.
- All Well Property Services hip-to-gable cost, read 2026-10-12:
A hip to gable loft conversion cost in 2026 usually falls in the £45,000 to £75,000+ range, and London projects often land toward the higher end because labour, access, compliance, and period-property detailing all push prices up.
- The Page loft conversion cost London, read 2026-10-12:
In London, the average cost of a loft conversion is about £45,000.
- Touchstone Lofts pricing, read 2026-10-12:
Rooflight loft conversions – from £40,000
- Signature Build Properties loft conversion cost, read 2026-10-12:
Before we look at London-specific prices, here is the UK-wide picture for 2026. Overall, the average loft conversion in the UK costs between £40,000 and £75,000 for a standard dormer on a three-bedroom terraced house.
- Excellence Living Bristol loft conversion cost, read 2026-10-12:
A loft conversion cost with Excellence Living starts from £40,000 for a rooflight conversion, rising to £55,000 for a dormer loft conversion and £55,000 for a gable loft conversion.
- Force One Homes loft extension cost guide, read 2026-10-12:
The dormer loft conversion price usually ranges from £35,000–£60,000, depending on size and finish.
- LCCL Construction loft conversion cost, read 2026-10-12:
The next most affordable is a dormer from £30,000.
- Everest conservatory cost, read 2026-10-12:
The average cost of a conservatory is from £27,000.
- Alstruct loft conversion cost London, read 2026-10-12:
A Velux (rooflight) conversion starts from £25,000–£45,000; a dormer from £45,000–£75,000; and a Mansard from £60,000–£100,000+.
- Signature Build Properties loft conversion cost, read 2026-10-12:
A simple Velux conversion can start from around £25,000 in less expensive parts of the country.
- Corsol Conversions garage conversion cost, read 2026-10-12:
A double garage conversion may range from £20,000 to £45,000 or more, especially if structural changes or plumbing are required.
- LCCL Construction loft conversion cost, read 2026-10-12:
A Velux or rooflight conversion is the cheapest, starting from £18,000.
- The Conversion Guy garage conversion cost, read 2026-10-12:
A single garage conversion typically ranges from £10,000 to £20,000, but the final figure depends in part on the garage type; an integral garage, built into the main house rather than attached or detached, is often one of the more straightforward options and a practical way to reclaim valuable living space.
- North East Garage Conversions average cost, read 2026-10-12:
Integral Garage - From £7,500
Read in full, publishes no figure
7 named sources were read in full on the dates shown and print no usable figure. They are counted, never filled in.
- CSW Lofts (Bristol) loft conversion costs, read 2026-10-12: every candidate on the page was refused
- Moduloft modular loft conversion (Manchester), read 2026-10-12: read in full and no accepted figure on the page
- Lilly Lewarne Architects double storey extension cost, read 2026-10-12: every candidate on the page was refused
- Studio Colab London house extension cost, read 2026-10-12: every candidate on the page was refused
- RED Builders refurbishment costs (London, Surrey, Essex, Kent, Herts), read 2026-10-12: every candidate on the page was refused
- MyBuilder loft conversion price guide, read 2026-10-12: every candidate on the page was refused
- Federation of Master Builders single-storey extension costs, read 2026-09-12: every candidate on the page was refused
Methodology
Every row is a verbatim sentence read from the named source's own page through our fetch service on the date shown, hash-pinned to the stored read (the sha of the page's visible text; the raw page is mirrored to R2).
25 of the 32 named sources that could be read published a usable figure; 7 published none and are recorded as not published, never filled in; 6 could not be read (blocked, dead or unreachable) and count nowhere.
The headline figures (median, minimum, maximum, quartiles) are over ONE figure per source for each breakdown it prices, in GBP (a source's median where its page yielded several accepted sentences for one breakdown), so a page that gives figures for several breakdowns gives one for each and N counts 34 figures, never sentences; 261 candidate sentence(s) were refused by a reviewer with the reason recorded.
The fuller derivation this dataset is chartered to grow into (not yet what the figures above are; they are each source's own published figure as read): the median, minimum and maximum published price per conversion or extension TYPE (rooflight, dormer, hip-to-gable, mansard, L-shaped, modular; single-storey, double-storey, side-return, wrap-around, kitchen, orangery, conservatory, garage) and per region, computed across every GB firm that publishes one - plus the two things no single builder can state: the SHARE of firms that publish a price at all against those that quote only after a survey, and the spread between the cheapest and dearest published price for the same type in the same region.
Re-read monthly, so a type's price movement and a firm's repricing are themselves the figure.
261 candidate sentences on these pages were refused by a reviewer; each refusal and its reason is recorded in the review ledger.
Sources (38)
- Touchstone Lofts pricing(the publisher's own terms; quoted for reporting and comment)
- LCCL Construction loft conversion cost(the publisher's own terms; quoted for reporting and comment)
- Advance Architecture London loft conversion price guide(the publisher's own terms; quoted for reporting and comment)
- Alstruct loft conversion cost London(the publisher's own terms; quoted for reporting and comment)
- Signature Build Properties loft conversion cost(the publisher's own terms; quoted for reporting and comment)
- Build Team extension cost(the publisher's own terms; quoted for reporting and comment)
- Resi construction and extension cost guide(the publisher's own terms; quoted for reporting and comment)
- Lawsons Lofts loft conversion costs(the publisher's own terms; quoted for reporting and comment)
- Excellence Living Bristol loft conversion cost(the publisher's own terms; quoted for reporting and comment)
- CSW Lofts (Bristol) loft conversion costs(the publisher's own terms; quoted for reporting and comment)
- Home Conversion Scotland loft conversion Glasgow(the publisher's own terms; quoted for reporting and comment)
- Everest conservatory cost(the publisher's own terms; quoted for reporting and comment)
- Moduloft modular loft conversion (Manchester)(the publisher's own terms; quoted for reporting and comment)
- Extension Architecture mansard cost guide(the publisher's own terms; quoted for reporting and comment)
- All Well Property Services hip-to-gable cost(the publisher's own terms; quoted for reporting and comment)
- Mayfair Studio kitchen extension London(the publisher's own terms; quoted for reporting and comment)
- NGC Build kitchen extension cost London(the publisher's own terms; quoted for reporting and comment)
- JD Building London extension costs(the publisher's own terms; quoted for reporting and comment)
- Beams kitchen extension cost(the publisher's own terms; quoted for reporting and comment)
- North East Garage Conversions average cost(the publisher's own terms; quoted for reporting and comment)
- Corsol Conversions garage conversion cost(the publisher's own terms; quoted for reporting and comment)
- The Conversion Guy garage conversion cost(the publisher's own terms; quoted for reporting and comment)
- Force One Homes loft extension cost guide(the publisher's own terms; quoted for reporting and comment)
- Arkiplan two-storey extension cost(the publisher's own terms; quoted for reporting and comment)
- Lilly Lewarne Architects double storey extension cost(the publisher's own terms; quoted for reporting and comment)
- The Page loft conversion cost London(the publisher's own terms; quoted for reporting and comment)
- Studio Colab London house extension cost(the publisher's own terms; quoted for reporting and comment)
- Loft Conversion UK mansard page(the publisher's own terms; quoted for reporting and comment)
- SPS Roofing mansard loft conversion cost(the publisher's own terms; quoted for reporting and comment)
- RED Builders refurbishment costs (London, Surrey, Essex, Kent, Herts)(the publisher's own terms; quoted for reporting and comment)
- Simply Loft loft conversion costs(the publisher's own terms; quoted for reporting and comment)
- Absolute Lofts loft conversion cost(the publisher's own terms; quoted for reporting and comment)
- Simply Extend costs(the publisher's own terms; quoted for reporting and comment)
- Luxury London Lofts costs 2026(the publisher's own terms; quoted for reporting and comment)
- MyBuilder loft conversion price guide(the publisher's own terms; quoted for reporting and comment)
- Federation of Master Builders single-storey extension costs(the publisher's own terms; quoted for reporting and comment)
- google.com(the publisher's own terms; quoted for reporting and comment)
- find-and-update.company-information.service.gov.uk(the publisher's own terms; quoted for reporting and comment)
Cite or embed this figure
Cite or embed this figure
For rooflight, the median published figure in the Extension Loft Price Index is 32,500 GBP across 6 figures from the sources' own pages (range 18,000 to 55,000 GBP), read 12 October 2026.
25 of the 32 named sources read in full publish a figure; 7 publish none, read 12 October 2026.
Extension Loft Price Index, type conservatory: median 27,000 GBP across 1 source, read 12 October 2026.
Extension Loft Price Index, type dormer: median 42,500 GBP across 6 sources, read 12 October 2026.
Extension Loft Price Index, type hip-to-gable: median 55,000 GBP across 3 sources, read 12 October 2026.
Extension Loft Price Index, type rooflight: median 32,500 GBP across 6 sources, read 12 October 2026.
Extension Loft Price Index, type L-shaped dormer: median 62,500 GBP across 2 sources, read 12 October 2026.
Extension Loft Price Index, type mansard: median 50,000 GBP across 5 sources, read 12 October 2026.
Extension Loft Price Index, type single-storey extension: median 55,000 GBP across 1 source, read 12 October 2026.
Extension Loft Price Index, type kitchen extension: median 71,400 GBP across 3 sources, read 12 October 2026.
Extension Loft Price Index, type double-storey extension: median 102,500 GBP across 2 sources, read 12 October 2026.
Extension Loft Price Index, type garage conversion: median 10,000 GBP across 3 sources, read 12 October 2026.
Cite as: "Roofing Quotes UK Extension Loft Price Index", updated 2026-10-19, https://roofingquotesuk.com/datasets/extension-loft-price-index/.
Download the CSV (34 rows, computed 2026-10-19)