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Building Safety Programme: estimates of EWS1 requirements on residential buildings in England

Estimates of EWS1 requirements on residential buildings in England

Proportions of cladding – building estimates

After the Grenfell Tower fire, the government established the Building Safety Programme to ensure that residents of high-rise residential buildings are safe, and feel safe from the risk of fire, now and in the future.

Alongside investigating the presence of Aluminium Composite Material (ACM) on buildings in England, and its remediation (see monthly data), the Programme continues to assess safety risks to other high-rise buildings and support action if there is a risk to public safety.

As part of this, all local authorities and housing associations in England provide data to the Department on the combination of the external wall facing material and insulation for each separate External Wall System (EWS) on their buildings. A building can consist of multiple external wall systems.

The EWS data collection aims to collect data on all high-rise residential buildings across England. The data collection is still in progress and is currently being further quality assured prior to full analysis and publication. It is judged that the data collected and presented here is of sufficient quality for the purposes of this analysis.

Table 1 shows the proportions of high-rise residential buildings with little or no cladding in place as part of their external wall system.
EWS1 requirements

The estimates shown in Table 1 are the proportions of high-rise residential buildings with no cladding, or buildings without a significant proportion of cladding. These estimates are based on data collected from the EWS data collection as at summer 2020.

The data used in this analysis includes buildings 18 metres or higher and includes all tenures: social residential, private residential, hotels and student accommodation and are as reported by data providers.

The proportion of cladding defined as significant is 20% or above of the external surface of the building. The definition of what constitutes cladding can be found in the Definitions section below. More information on the analysis conducted can be found in the Methodology section below.

Leasehold dwellings

This analysis focuses on leasehold dwellings as EWS1 forms are required as part of the mortgage valuations process. Dwellings rented by social tenants will not be affected. The definition of leasehold dwellings can be found in the Definitions section below.

The total number of high-rise residential multi-occupied buildings of 18 metres or more in height, or more than 6 storeys (whichever is reached first), in England is estimated as of April 2020 to be 12,500. Of these, approximately 6,000 are private residential buildings and 6,000 are social residential buildings.

This split excludes student accommodation and hotels and is based on analysis that 50% are private sector residential buildings, containing purely leasehold dwellings, and 50% are social sector residential buildings where 28% of dwellings within are private leasehold (see Methodology section below).

The total number of buildings between 11 and 18 metres in height in England is estimated as of September 2020 to be 77,500. Excluding student accommodation and hotels, there are an estimated 38,000 private residential buildings and 38,000 social residential buildings.

As there is not yet adequate data to form an estimate of the private/social split of residential buildings between 11 and 18 metres, the same proportions are used as those used to calculate buildings over 18m, as above. Therefore, the estimates for 11-18m buildings are subject to greater uncertainty but are of sufficient quality for the purposes of this analysis. An estimated 16% of dwellings within 11-18m social residential buildings are private leasehold (see Methodology section below).
(a) Includes dwellings rented by social tenants
(b) Excludes dwellings rented by social tenants as these are not leasehold dwellings

Table 3 shows that an estimated 46,000 (52%) private and social residential buildings should not require an EWS1 process when buildings below 18m in height with insignificant amounts of cladding are also not required to undergo an EWS1 process. We estimate that there are 610,000 leasehold dwellings in those buildings.

Updated analysis

The analysis above shows the estimated impact of policy refinements and assurances from major lenders and wider industry, including the Royal Institution of Chartered Surveyors (RICS), that residential buildings with no cladding will no longer need to undergo an external wall survey (EWS1 form) before dwellings can be sold or re-mortgages offered. This was announced on 21 November 2020.

On 8 March 2021 RICS produced a further guidance note to clarify when an EWS1 should be used. MHCLG has conducted indicative analysis to estimate the impact of this guidance note, further to the previous announcement on 21 November 2020.

As a result of this guidance, we estimate a net increase of 61,000 leaseholders of flats in buildings over 11 metres in height not requiring an EWS1 form from valuers or lenders. This is a 14% increase, rising to 492,000 leaseholders from the original published estimate of 431,000.

This increase is a result of various changes in the criteria for buildings to require an EWS1 form. Some changes place fewer buildings in scope such as the exclusion of 11-18m buildings with minimal cladding (classed as less than 25% coverage) when previously all 11-18m buildings with any cladding, irrespective of the proportion of coverage, were included. This has had the greatest influence on the change in leaseholders not impacted by EWS1 forms. 11-18m buildings with any panels of aluminium composite material (ACM), metal composite material (MCM) or high-pressure laminate (HPL) present will still require an EWS1 form. Other changes to the criteria have captured more buildings. For example, all buildings over 11m with vertically stacked balconies made partially or wholly from combustible materials are now included.

The updated analysis also uses MHCLG’s latest published estimate of the average number of dwellings in high-rise buildings.

The estimated net change of the guidance and methodology described above, is an increase to: 492,000 leaseholders in buildings over 11m in height will not require an EWS1 form for their building in order for them to sell their property or re-mortgage.

Technical notes

Cladding: For the purposes of analysis, the following materials have been categorised as cladding: aluminium composite material (ACM), brick slips, high pressure laminate (HPL), metal composite material (MCM), metal sheet panels, render system, plastic, tiling systems, and timber or wood.

Dwelling: A self-contained unit of accommodation.

External Wall System (EWS): External wall systems are the combination of the external facing material (e.g. brick) and the insulation within the external wall. Each building may have one or more external wall systems.

Flat: A dwelling which forms part of a building, usually separated by a horizontal divide.

Leasehold: A system whereby an individual owns a property but not the land upon which the property is built.

Leasehold dwelling: A dwelling that is owned by a leaseholder but the building and land upon which is it built remains the property of a freeholder.

Non-cladding: For the purposes of analysis, the following materials have been categorised as non-cladding: brick, stone panels or stone, concrete and glass.

Private sector residential building: A building is classified as a private sector residential building if the freeholder is a private company and contains at least one dwelling occupied as private residential accommodation. Private sector residential buildings exclude hotels and student accommodation.

Social sector residential building: A building is classified as a social sector residential building if the freeholder is a registered social landlord and there is at least one social tenant living in the building.

Social tenant: A tenant who rents their dwelling at a reduced rate from a housing association or council, who act as the landlord. Social tenants are not regarded as living in leasehold owned dwellings.

Unique Property Reference Number (UPRN): A unique identifier for every addressable location in Great Britain.

Data Collection

Since summer 2017 MHCLG have collected data on residential buildings 18 metres and above in height from a range of sources.

External wall system and coverage data comes from the External Wall System (EWS) data collection.

The department launched the EWS data collection on 18 July 2019. The EWS data collection collects information on the external wall materials and insulation on all high-rise residential buildings 18m and over in England. The collection is still in progress.

Local authorities and housing associations provide data on the combination of the external wall facing material and insulation for each separate EWS on their buildings. A building can consist of multiple external wall systems.

Data is received from local authorities and housing associations regarding the external wall systems in place on their high-rise residential stock (social and private), including student accommodation and hotels. Organisations submit data to the department via our online DELTA system.

Dwelling estimates data come from a range of sources for residential buildings 18 metres and above and 11-18 metres:
  • Local authority confirmation – following local authorities providing updates on their own building stock in the social sector and working with building owners and agents
  • Housing association confirmation – following housing associations providing updates on their own building stock in the social sector and where they act as head lessors in the private sector
  • Discussions with responsible stakeholders – including building owners, developers and agents
  • English Housing Survey (EHS) – for the proportion of dwellings in 11-18m and 18m+ buildings that are in the private (as opposed to social) sector
  • Ordnance Survey ® (OS ®) AddressBase – geographic information from the national mapping agency which carries out the official surveying of Great Britain
  • Valuation Office Agency property attribute data – to validate the number of dwellings in high-rise residential buildings


The EWS collection receives data on coverage in specified bands e.g. 0-20%, 21-40%, up to 100%. For analysis, the midpoint of each coverage band was used e.g. instead of 0-20% the midpoint of 10% was used, so that each material had a single percentage coverage.

Additionally, the EWS collection allows for an “Other specify” option on the form for the external facing material. “Other specify” responses which referred to concrete and stone materials were recoded and included in this analysis. Other records with “Other specify” responses and “Do not know” for the external facing material were excluded from analysis, as not enough information was provided to determine whether they constituted ‘cladding’ as defined in the Definitions section above.

For the remaining records, with complete data and a full provision of external facing materials, the percentage coverage was summed where materials were categorised as ‘cladding’ for each record. This produces an overall percentage of cladding coverage for each building, which were used to calculate the proportions in Table 1.

For the estimated proportion of 11-18m buildings in the private sector and private (leasehold) dwellings in social sector buildings we have used the figures reported in the EHS for purpose-built flats, low rise, and for 18m+ we have used figures for purpose-built flats, high rise. The categories do not map perfectly but we expect them to be a reasonable proxy. See more information on the EHS.

The External Wall Systems collection does not collect information regarding the position of the balconies e.g., whether balconies are vertically stacked or linked by combustible materials. To estimate the proportion of balconies requiring an EWS1 form, the proportion of combustible balconies was used, based on whether the balcony balustrade and flooring were made from combustible materials (wood, other, do-not-know).

RICS also refer to building height categories of 5-6 storeys and those over 6 storeys to increase the ease of assessors identifying building heights. As we do not currently hold estimates of building height by storey for buildings under 18m, we have used a building’s height in metres to provide our best estimate of the impact.

Data quality

The EWS collection is in progress, and so findings may differ when the full set of data has been finalised. The EWS information is currently going through collation, checks and clearances to ensure accuracy.

Quality is dependent on returns from a wide range of providers. In this release data is as reported by local authorities and housing associations. Poor quality returns were excluded from analysis. Further information from the EWS collection will be published in due course.

Estimates for 11-18m buildings have been calculated by applying the same assumptions as for high-rise stock to the Department’s estimate for 11-18m buildings. The Department has begun a pilot data collection project for 11-18m buildings to produce a prevalence estimate and to inform the design of a wider national 11-18m data collection exercise.

This work will provide information on how local authorities, other building owners and external partners can work together to collect this data, and the resource implications for this. Development of this work, its scope and coverage is currently in design. Further details on this work will be provided in due course.

The leasehold dwellings estimates provided in the publication are subject to change as data coverage and quality is continually assessed and improved. Data for approximately two-thirds of the Building Safety Programme’s residential building count were used to calculate dwellings estimates as a result of data gaps.

For 11-18m buildings, there are many more buildings at the lower end of the height range which may skew the estimated number of dwellings per building and provide a lower figure than expected. In addition, there are some extremely low values for dwellings such as 3 or fewer per building.

As part of the estimate is based on a count of unique property reference numbers (UPRNs) and the UPRN represents the hierarchy of the address, this may not always correspond to the precise structure of the flats contained in the building. Therefore, dwellings estimates could be subject to under or over estimation. Combined with estimates of EWS coverage for these buildings, this creates more uncertainty.
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