Key findings
- Great Britain has an estimated 8.5 million solid-walled homes, and 89% of them (7.6 million) have no solid wall insulation (DESNZ, end of 2025).
- The National Audit Office estimates that 98% of external wall insulation jobs under ECO4 and the Great British Insulation Scheme had major issues needing remediation, affecting an estimated 22,000 to 23,000 homes.
- Installed wall insulation in homes is zero-rated for VAT until 31 March 2027, then 5%. Render on its own is not an energy-saving material.
- In the South East, the share of homes failing the Decent Homes Standard rose from 11% to 17% between 2022 and 2024.
- Guildford borough has 40 conservation areas and Rushmoor (Farnborough and Aldershot) has 9. Rendering a house in one needs planning permission. The national householder fee is £548 from 1 April 2026.
- Two national cost guides published in August and September 2026 agree on silicone render at £60 to £100 per m². Applying the published 15% to 30% South East uplift gives £69 to £130 per m².
- About 90% of the year's air frosts fall between November and March at the nearest published South East station, which is why render systems with a 5°C minimum are best applied from spring to autumn.
Wall types and insulation
Solid walls are where render, external wall insulation and lime work matter most. Official estimates show almost nine in ten solid-walled homes are still uninsulated, against about seven in ten cavity-walled homes that have been filled. The pace of change is slow: about 29,600 homes gained solid wall insulation in the year to December 2025.
| Statistic | Figure | Area and period | Source |
|---|---|---|---|
| Homes with solid walls | 8.5 million | Great Britain End of December 2025 | [1] Official estimate |
| Solid-walled homes with solid wall insulation | 909,000 (11%) | Great Britain End of December 2025 | [1] Official estimate |
| Solid-walled homes without solid wall insulation | 7.6 million (89%) | Great Britain End of December 2025 | [1] Official estimate |
| Increase in homes with solid wall insulation over the yearAll assumed to be retrofit | About 29,600 (+3.4%) | Great Britain Year to December 2025 | [1] Official estimate |
| Homes with cavity walls | 21.8 million | Great Britain End of December 2025 | [1] Official estimate |
| Cavity-walled homes with cavity wall insulation | 15.4 million (71%) | Great Britain End of December 2025 | [1] Official estimate |
| Cavity-walled homes without cavity wall insulation | About 5.0 million (3.7 million easy to treat, 1.3 million hard to treat) | Great Britain End of December 2025 | [1] Official estimate |
| Share of Great British Insulation Scheme measures that were solid wall insulation | About 4% | Great Britain Scheme to end of 2025 | [1] Official estimate |
| Dwellings with cavity or solid wall insulation | 54% (48% in 2014) | England 2024 | [2] Survey estimate |
| Dwellings with solid wall insulation | 4% of all dwellings (3% in 2022) | England 2024 | [2] Survey estimate |
Housing condition and damp
Penetrating damp is the type most often linked to cracked render, render bridging the damp-proof course and missing drips. It has doubled as a share of English homes since 2019, from 1% to 2%. The South East has moved against the national trend on housing quality, with owner-occupied non-decent homes rising from 10% to 16% in two years.
| Statistic | Figure | Area and period | Source |
|---|---|---|---|
| Dwellings with any damp problem | 1.4 million (5%) | England 2024 | [4] Survey estimate |
| Dwellings with penetrating dampPenetrating damp is the type most often linked to failed render and defective detailing | 2% (1% in 2019) | England 2024 | [3] Survey estimate |
| Privately rented dwellings with penetrating damp | 4% | England 2024 | [3] Survey estimate |
| Dwellings failing the Decent Homes Standard | 4.0 million (15%) | England 2024 | [3] Survey estimate |
| Non-decent homes in the South East | 17% (11% in 2022) | South East England 2024 | [3] Survey estimate |
| Owner-occupied non-decent homes in the South East | 16% (10% in 2022) | South East England 2024 | [3] Survey estimate |
| Owner-occupied homes failing the Decent Homes disrepair criterion | 3% | England 2024 | [3] Survey estimate |
Energy performance and upgrade costs
More than half of English homes are now in EPC bands A to C. The modelled cost of bringing a home up to band C rises steeply for the least efficient homes, which are often older solid-walled houses where external wall insulation is one of the larger single measures.
| Statistic | Figure | Area and period | Source |
|---|---|---|---|
| Average SAP energy rating | 68 (45 in 1996) | England 2024 | [2] Survey estimate |
| Dwellings in EPC bands A to C | 56% (26% in 2014) | England 2024 | [2] Survey estimate |
| Dwellings in EPC bands E to G | 9% (23% in 2014) | England 2024 | [2] Survey estimate |
| Owner-occupied homes in EPC band C | 49% | England 2024 | [2] Survey estimate |
| Mean modelled cost to bring a dwelling up to EPC band CModelled improvement cost; not specific to wall insulation | £7,480 (median £8,648) | England 2024 | [2] Survey estimate |
| Mean modelled cost to band C for owner-occupied homes | £7,869 | England 2024 | [2] Survey estimate |
| Mean modelled cost to band C by current band | D £6,002; E £12,430; F or G £17,354 | England 2024 | [2] Survey estimate |
Quality of grant-funded wall insulation
The most significant recent finding for anyone considering external wall insulation is the National Audit Office's October 2025 report. Its estimates come from audits of 758 projects and exclude homes insulated from 16 January 2025 onwards. For homeowners, the practical lesson is to check who designs, installs and inspects the work, and what the guarantee covers, before signing. See render guarantees and warranties.
| Statistic | Figure | Area and period | Source |
|---|---|---|---|
| External wall insulation jobs under ECO4 and GBIS with major issues needing remediationExtrapolated from audits of 758 projects | 98% | Great Britain Installs audited to 15 January 2025 | [5] Audit estimate |
| External wall insulation jobs with issues affecting performance | 92% | Great Britain Installs audited to 15 January 2025 | [5] Audit estimate |
| External wall insulation jobs with an immediate health and safety risk | 6% | Great Britain Installs audited to 15 January 2025 | [5] Audit estimate |
| Estimated homes with major external wall insulation issues | 22,000 to 23,000 | Great Britain Installs audited to 15 January 2025 | [5] Audit estimate |
| Internal wall insulation jobs with major issues | 29% | Great Britain Installs audited to 15 January 2025 | [5] Audit estimate |
| External wall insulation homes fully remediated | 1,901 (8% of the estimate) | Great Britain Mid-September 2025 | [5] Audit figure |
| Estimated cost to remediate a defective external wall insulation jobTrustMark estimate quoted by the NAO | £5,000 to £18,000 per property | Great Britain 2025 | [5] Audit estimate |
Grants and VAT
Supplier-funded schemes have been the main route to grant-funded wall insulation. The Great British Insulation Scheme closed on 31 March 2026, and the Warm Homes Plan is the successor framework. See our external wall insulation grants guide for eligibility and how to protect yourself on funded work.
| Statistic | Figure | Area and period | Source |
|---|---|---|---|
| Great British Insulation Scheme measures installed | 139,100 | Great Britain 30 March 2023 to 31 March 2026 (provisional) | [6] Official statistics |
| Households helped by the Great British Insulation Scheme | 100,900 | Great Britain 30 March 2023 to 31 March 2026 (provisional) | [6] Official statistics |
| Cavity wall insulation share of GBIS measures | 37% (51,400) | Great Britain To 31 March 2026 | [6] Official statistics |
| Great British Insulation Scheme closing date | 31 March 2026 | Great Britain 2026 | [8] Reported fact |
| Warm Homes Plan funding announced | £15 billion | England January 2026 | [8] Reported fact |
| VAT on installed energy-saving materials including wall insulation in homesRender on its own is not listed as an energy-saving material | 0% | United Kingdom 1 May 2023 to 31 March 2027 | [7] Tax rule |
| VAT on installed energy-saving materials from 1 April 2027 | 5% | United Kingdom From 1 April 2027 | [7] Tax rule |
| VAT on energy-saving materials supplied without installation | Standard rate | United Kingdom Current | [7] Tax rule |
Guildford local context
Guildford's heritage designations shape what rendering work needs permission. The Census also shows private renting rising as a share of households, which matters because private rented homes have the highest rates of penetrating damp and disrepair in the English Housing Survey.
| Statistic | Figure | Area and period | Source |
|---|---|---|---|
| Population | About 143,600 (+4.7% since 2011) | Guildford borough Census 2021 | [9] Official statistics |
| Households that own their home outright or with a mortgage | 66.3% (68.8% in 2011) | Guildford borough Census 2021 | [9] Official statistics |
| Households renting privately | 19.6% (15.8% in 2011) | Guildford borough Census 2021 | [9] Official statistics |
| Conservation areas | 40 | Guildford borough Undated council document | [10] Local authority figure |
| Listed buildings | More than 1,000 | Guildford borough Undated council document | [10] Local authority figure |
| Confirmed Article 4 directions | 7 (including Town Centre, St Catherine's, Shere, Onslow Village) | Guildford borough Undated council document | [10] Local authority figure |
Farnborough and Rushmoor
Farnborough sits just over the county boundary in Hampshire, in Rushmoor borough. That changes who issues scaffold licences: Hampshire County Council, with ten clear working days' notice, rather than Surrey County Council. See exterior house rendering in Farnborough.
| Statistic | Figure | Area and period | Source |
|---|---|---|---|
| Conservation areas in Rushmoor borough | 9 | Rushmoor borough June 2025 | [23] Local authority figure |
| Conservation areas in Farnborough | Farnborough Hill and Farnborough Street (both designated 2025); South Farnborough (designated 1987, reviewed 2025) | Farnborough June 2025 | [23] Local authority figure |
| Hampshire highway licence for scaffoldingFarnborough is in Hampshire so Surrey fees do not apply | £211.90 for the first 2 weeks | Hampshire (including Farnborough) Current | [24] Fee schedule |
| Each additional 2 weeks of a Hampshire scaffolding licenceApply for the full period: extensions are not offered | £72 | Hampshire Current | [24] Fee schedule |
| Notice needed for a Hampshire scaffolding licence | At least 10 clear working days before the start date | Hampshire Current | [24] Fee schedule |
| Population | About 99,800 (+6.3% since 2011) | Rushmoor borough Census 2021 | [25] Official statistics |
| Households that own their home | 60.5% (63.5% in 2011) | Rushmoor borough Census 2021 | [25] Official statistics |
| Households renting privately | 21.5% (17.6% in 2011) | Rushmoor borough Census 2021 | [25] Official statistics |
Planning, permits and neighbours
Most re-rendering outside protected areas needs no planning application, but conservation areas, National Landscapes such as the Surrey Hills and listed buildings change that. Scaffolding and skips on the public highway need Surrey County Council licences. See planning permission for rendering and party walls and neighbour access.
| Statistic | Figure | Area and period | Source |
|---|---|---|---|
| Planning permission needed to render a house in a conservation area or Area of Outstanding Natural Beauty (National Landscape)Also National Parks and the Broads | Yes | England Current | [11] Regulatory guidance |
| Planning permission needed to re-render outside protected areasA change of type or colour may need permission | Usually not, if the finish is of similar appearance | England Current | [11] Regulatory guidance |
| National planning fee for a householder application | £548 | England From 1 April 2026 | [12] Fee schedule |
| Fee for listed building consent | No fee | England From 1 April 2026 | [12] Fee schedule |
| Surrey highway licence for scaffolding or hoarding | £208 per 28 days (including VAT) | Surrey Current schedule | [13] Fee schedule |
| Surrey permit for a skip on the highway | £139 for up to 28 days | Surrey Current schedule | [13] Fee schedule |
| Notice period for work to an existing party wallExternal walls that are not party walls fall outside the Act | Two months | England and Wales Party Wall etc. Act 1996 | [14] Statute guidance |
| Notice to a neighbour before access to their land under the Party Wall ActApplies only to works under the Act; scaffold access for rendering is usually agreed in writing instead | 14 days | England and Wales Party Wall etc. Act 1996 | [14] Statute guidance |
Materials and application
These figures are manufacturer specifications, not independent test results. They are included because they set the conditions a contractor must follow for a system to perform as designed, and they are the basis of most manufacturer warranties.
| Statistic | Figure | Area and period | Source |
|---|---|---|---|
| Minimum air and substrate temperature for K-Rend Silicone TC | 5°C | Manufacturer specification Current datasheet | [15] Manufacturer claim |
| Coverage of K-Rend Silicone TC 15 (1.5 mm grain) | About 2.5 kg/m² | Manufacturer specification Current datasheet | [15] Manufacturer claim |
| Coverage of K-Rend Silicone TC 30 (3.0 mm grain) | About 5.0 kg/m² | Manufacturer specification Current datasheet | [15] Manufacturer claim |
| Minimum wait on base coats before a K-Rend silicone topcoat | 14 days (primer 24 hours) | Manufacturer specification Current datasheet | [15] Manufacturer claim |
| K-Rend Silicone TC water vapour permeability and water absorption classes | V2 and W3 (BS EN 15824) | Manufacturer specification Current datasheet | [15] Manufacturer claim |
| Application temperature range for weberpral M monocoucheBBA certificates 17/5464 and 17/EP1005 | 5°C to 30°C | Manufacturer specification Current listing | [16] Manufacturer claim |
| Surrey councils' advice on hard cement render on traditional walls | Avoid: impermeable cement render traps moisture; use low-cement lime mixes | Surrey Undated leaflet | [17] Conservation guidance |
Weather and the rendering season
The Met Office does not publish long-term averages for a Guildford station on the page we used, so these figures come from East Malling in Kent, the nearest South East station available on that source. Treat them as indicative of the region rather than of Guildford itself. See the best time of year to render.
| Statistic | Figure | Area and period | Source |
|---|---|---|---|
| Days of air frost a yearNot a Guildford station; indicative for the South East | 39.4 | East Malling (nearest published South East station on this source) 1991 to 2020 average | [18] Climate average |
| Days a year with 1 mm or more of rainNot a Guildford station | 115.1 | East Malling 1991 to 2020 average | [18] Climate average |
| Air frost days from November to March | 35.6 (Nov 4.5, Dec 9.3, Jan 8.6, Feb 8.3, Mar 4.9) | East Malling 1991 to 2020 average | [18] Climate average |
Published rendering prices
Online cost guides are commercial estimates, not measured prices. We compared three guides updated between August and October 2026. They broadly agree on silicone, monocouche and sand and cement, and disagree most on external wall insulation, where upper figures differ by £50 per m². None states clearly whether prices include VAT. MyJobQuote was used only for day rates and duration, because its per-m² table mixes supply-only and installed figures.
| Statistic | Figure | Area and period | Source |
|---|---|---|---|
| Silicone thin-coat render per m²VAT treatment not stated by either guide | £60 to £100 (BestBuilders); £60 to £100 (MyBuilder) | UK national Aug to Sep 2026 | [19] [20] Commercial estimate |
| Monocouche render per m²VAT treatment not stated | £50 to £70 (BestBuilders); £50 to £80 (MyBuilder) | UK national Aug to Sep 2026 | [19] [20] Commercial estimate |
| Sand and cement render per m²Painting extra | £40 to £60 (BestBuilders); £40 to £60 (MyBuilder) | UK national Aug to Sep 2026 | [19] [20] Commercial estimate |
| Acrylic thin-coat render per m² | £55 to £90 (BestBuilders); £50 to £70 (MyBuilder) | UK national Aug to Sep 2026 | [19] [20] Commercial estimate |
| External wall insulation with render per m² | £100 to £200 (BestBuilders); £90 to £150 (MyBuilder) | UK national Aug to Sep 2026 | [19] [20] Commercial estimate |
| Lime render per m² | £60 to £95 | UK national September 2026 | [19] Commercial estimate |
| Silicone render on a three-bed semi (90 to 120 m²) | £7,000 to £11,000 | UK national September 2026 | [19] Commercial estimate |
| Silicone render on a 3 to 4-bed detached house (140 to 200 m²) | £10,500 to £18,000 | UK national September 2026 | [19] Commercial estimate |
| Scaffolding for a full two-storey semi | £800 to £1,600 | UK national September 2026 | [19] Commercial estimate |
| Removing old render | £10 to £25 per m², often £1,000 to £3,000 a house | UK national September 2026 | [19] Commercial estimate |
| London and South East price uplift on national figures | 15% to 30% | London and South East September 2026 | [19] Commercial estimate |
| Rendering specialist day rate | £130 to £250 | UK national October 2026 | [21] Commercial estimate |
| Typical duration to render a houseExcludes weather delays and curing waits | 7 to 10 days | UK national October 2026 | [21] Commercial estimate |
For a figure for your own house, use the rendering cost calculator or read house rendering costs in Guildford.
Our analysis
These figures are our own calculations from the sources above. Each row shows the inputs so the working can be checked.
| Statistic | Figure | Area and period | Source |
|---|---|---|---|
| Share of the year's air frosts falling between November and March35.6 of 39.4 frost days | 90% | East Malling Derived from 1991 to 2020 averages | [18] Calculated |
| Highway licence cost for a six-week scaffold in SurreyOnly where scaffold stands on the public highway | £416 (two 28-day periods) | Surrey Derived | [13] Calculated |
| Silicone topcoat needed for a 105 m² semi at 2.5 kg/m² | About 263 kg, or 11 25 kg tubs before waste | Manufacturer specification Derived | [15] Calculated |
| South East silicone range after applying the published uplift to the national range£60 to £100 national with 15% to 30% uplift | £69 to £130 per m² | South East Derived | [19] [20] Calculated |
| Householder planning fee as a share of a silicone semi job£548 against £7,000 to £11,000 | 5% to 8% | England Derived | [12] [19] Calculated |
| Remediation cost of a defective EWI job as a share of the published EWI price for a semi£5,000 to £18,000 remediation against £12,000 to £20,000 for EWI on a semi | 25% to 150% | Great Britain Derived | [5] [19] Calculated |
| Hampshire highway licence cost for a six-week scaffoldOnly where scaffold stands on the public highway | £355.90 (£211.90 + 2 × £72) | Hampshire Derived | [24] Calculated |
Methodology
- Research question: what verifiable evidence is available to a Surrey homeowner, journalist or contractor about walls, wall insulation, damp, rendering rules and rendering prices?
- Collection: desk research between 25 October 2026 and publication. Each figure was read from the original source page or document, not from a secondary article, except where a source is itself a summary (the Which? grants guide and the North Yorkshire Council summary of national planning fees).
- Source priority: official statistics, audit reports and government guidance first; local authority documents second; manufacturer specifications third; commercial cost guides last and only for prices.
- Geography: each row states whether it covers Great Britain, England, the South East, Surrey or Guildford borough. DESNZ insulation estimates cover Great Britain; the English Housing Survey covers England.
- Dates: each row gives the period the figure refers to, which is often earlier than the publication date.
- Calculations: rows in "Our analysis" are simple arithmetic on cited figures, with inputs shown. We have not adjusted any official figure.
- Excluded: figures we could not trace to an original source, competitor articles and unattributed statistics.
Limitations
- Survey estimates such as the English Housing Survey carry sampling error; small year-on-year changes may not be significant.
- The NAO estimates are extrapolated from audited samples and do not cover installations from 16 January 2025.
- Commercial cost guides do not publish their methods. They are useful as a cross-check, not as evidence of what any job will cost.
- Manufacturer figures describe products under the manufacturer's stated conditions.
- Some local authority documents are undated; we record the date we accessed them.
- We have not yet published original survey or project data. When we do, it will be added as a separate, clearly labelled section.
Citing this page
You are welcome to quote, chart or republish any figure here. Please credit the original source shown against the figure, and link to this page as the compilation: Guildford Render, "House rendering statistics 2026", https://www.guildfordrender.co.uk/house-rendering-statistics. Our own calculations can be credited to Guildford Render. Official statistics are reused under the Open Government Licence v3.0.
Spotted an error or a newer figure? Email hello@guildfordrender.co.uk. We correct errors promptly and log changes below.
Sources
- Department for Energy Security and Net Zero, Household Energy Efficiency Statistics: detailed release March 2026. Official statistics; published 2026-03; accessed 2026-10-25.
- Ministry of Housing Communities and Local Government, English Housing Survey 2024 to 2025: headline findings on housing quality and energy efficiency. Chapter 2: energy efficiency. Accredited official statistics; published 2026-01; accessed 2026-10-25.
- Ministry of Housing Communities and Local Government, English Housing Survey 2024 to 2025: headline findings on housing quality and energy efficiency. Chapter 1: housing quality. Accredited official statistics; published 2026-01; accessed 2026-10-25.
- Ministry of Housing Communities and Local Government, English Housing Survey 2024 to 2025: headline findings on housing quality and energy efficiency (chapters). Accredited official statistics; published 2026-01; accessed 2026-10-25.
- National Audit Office, Energy efficiency installations under the Energy Company Obligation (summary) HC 1334. Audit report; published 2025-10-14; accessed 2026-10-25.
- Department for Energy Security and Net Zero, Summary of the Great British Insulation Scheme: June 2026. Official statistics; published 2026-06-25; accessed 2026-10-25.
- HM Revenue and Customs, VAT on energy-saving materials and heating equipment (VAT Notice 708/6). Government guidance; published 2024-01-31; accessed 2026-10-25.
- Which?, Insulation grants guide. Consumer guide; published 2026-02-26; accessed 2026-10-25.
- Office for National Statistics, How life has changed in Guildford: Census 2021. Official statistics; published 2023; accessed 2026-10-25.
- Guildford Borough Council, Historic Environment Information. Local authority information; published undated; accessed 2026-10-25.
- Planning Portal, Do I need planning permission to render the outside of my house?. Government-backed guidance; published undated; accessed 2026-10-25.
- North Yorkshire Council, Guide to fees for planning applications in England. Local authority summary of national fees; published 2026-04; accessed 2026-10-25.
- Surrey County Council, Highway fees and charges. Local authority fees; published undated; accessed 2026-10-25.
- Department for Communities and Local Government, The Party Wall etc. Act 1996: explanatory booklet (copy hosted by High Peak Borough Council). Government guidance; published undated; accessed 2026-10-25.
- K-Rend, Silicone TC technical datasheet. Manufacturer specification; published undated; accessed 2026-10-25.
- Saint-Gobain Weber (via SpecifiedBy), weberpral M monocouche render product listing. Manufacturer specification; published undated; accessed 2026-10-25.
- Surrey County Council and Surrey district councils, Advisory Leaflet 7: Mortars plasters and renders (copy hosted by Spelthorne Borough Council). Local authority conservation guidance; published undated; accessed 2026-10-25.
- Met Office, East Malling climate averages 1991 to 2020. Official climate data; published 1991-2020 averages; accessed 2026-10-25.
- BestBuilders, House rendering cost UK. Commercial cost guide; published 2026-09-07; accessed 2026-10-25.
- MyBuilder, Rendering costs explained. Commercial cost guide; published 2026-08-21; accessed 2026-10-25.
- MyJobQuote, How much does it cost to render a house?. Commercial cost guide; published 2026-10-01; accessed 2026-10-25.
- Planning Portal, External walls: thermal resistance. Government-backed guidance; published undated; accessed 2026-10-25.
- Rushmoor Borough Council, Conservation areas overview document. Local authority information; published 2025-06; accessed 2026-10-25.
- Hampshire County Council, Apply for a scaffolding licence. Local authority fees; published undated; accessed 2026-10-25.
- Office for National Statistics, How life has changed in Rushmoor: Census 2021. Official statistics; published 2023; accessed 2026-10-25.
Change log
- 25 October 2026: added Farnborough and Rushmoor section (conservation areas, Hampshire scaffold licences, Census 2021 tenure); now 91 data points from 25 sources.
- 25 October 2026: first published with 82 data points from 22 sources.
Questions people ask
How many homes in the UK have solid walls?
DESNZ estimates 8.5 million homes in Great Britain had solid walls at the end of December 2025, of which 909,000 (11%) had solid wall insulation.
Is external wall insulation VAT-free?
Installed wall insulation in residential homes is zero-rated for VAT from 1 May 2023 to 31 March 2027, then 5% from 1 April 2027, under HMRC VAT Notice 708/6. Render that is not part of an insulation installation is standard-rated.
What did the National Audit Office find about external wall insulation?
It estimated that 98% of external wall insulation installations under ECO4 and the Great British Insulation Scheme had major issues requiring remediation, based on audits of 758 projects, with an estimated 22,000 to 23,000 homes affected.
How many conservation areas are there in Guildford?
Guildford Borough Council lists 40 conservation areas, more than 1,000 listed buildings and seven confirmed Article 4 directions.
Can I use these statistics in my article?
Yes. Credit the original source for each figure and link to this page as the compilation. The full dataset is available as a CSV download.