Research and analysis

Building materials and components statistics: product surveys methodology

Published 24 January 2025

Coverage: United Kingdom (UK)

1. Background

This document describes the methods used to obtain volume data for the following tables in the Building materials and components statistics publication:

• Tables 4 and 5: Sand and gravel
• Table 6: Roofing tiles and ready-mixed concrete
• Table 7: Slate
• Table 8: Cement and clinker
• Tables 9 and 10: Bricks
• Tables 11 and 12: Concrete blocks

The bulk of this data comes from surveys of production sites done on a monthly or quarterly basis by the Office for National Statistics (ONS) on behalf of the Department for Business and Trade (DBT).

These surveys are a mix of statutory surveys, where respondents are legally obliged to report data under the Statistics of Trade Act 1947 and voluntary surveys. For non-responding sites, various data imputation methods are used.

In order to prevent sensitive business data being published, disclosure methods are applied to various products.

Seasonal adjustment is applied to some products due to the significant effect on seasonal and weather conditions on the construction industry.

2. Sand and gravel

2.1 Type of data

Sand and gravel data is presented as volume (tonnes) sales of sand and gravel published on a quarterly basis. Sales values are broken down into different categories:

• sand for building
• sand for concreting
• gravel for concreting and other uses
• sand and gravel for coating
• sand, gravel and hoggin for fill

Data is also presented with a regional breakdown into Scotland, Wales and the English regions. Data is collected and compiled by ONS on behalf of DBT.

Sand and gravel outputs are produced from 2 types of data:

• marine-dredged sand and gravel
• land-won sand and gravel

2.2 Marine-dredged sand and gravel survey

Marine-dredged sand and gravel data is collected using a quarterly statutory survey. As this survey is intended to be a census, data from the British Geological Survey (BGS) is used to provide information on marine-dredged sand and gravel sites.

The marine-dredged sand and gravel survey currently has a sample size of around 70. Further details of the survey can be found on the ONS website.

2.3 Land-won sand and gravel survey

Land-won sand and gravel data is collected using a quarterly statutory survey, which like the marine dredged survey is also run as a census using site information supplied by the BGS.

The land-won sand and gravel survey currently has a sample size of around 70. Further details of the survey can be found on the ONS website.

2.4 Imputation of data

Where a site does not respond to the sand and gravel survey, data is imputed based on data from other responding sites within the same region and the past contribution of the non-responding site to the survey.

2.5 Disclosure control

Some of the data in the sand and gravel survey is considered disclosive as its publication could risk sensitive business information being released. In order to eliminate such risk, DBT implements disclosure control algorithms which suppress data points where disclosive data may be released.

2.6 Seasonal adjustment

As sales of sand and gravel fluctuate significantly based on time of year, DBT applies seasonal adjustment methods to total quarterly sales of sand and gravel using X13-ARIMA methodology. The past 12 years of data are used to educate the seasonal adjustment algorithm, and the specifications used for seasonal adjustment are reviewed annually to ensure the algorithm remains robust.

3. Roofing tiles and ready-mixed concrete

3.1 Types of data

Concrete roofing tiles and ready-mixed concrete (RMC) data is presented in the same table in the publication, despite coming from different sources.

Concrete roofing tiles data is presented as volume (square metres) data on production, deliveries and stocks in Great Britain on a quarterly basis, while RMC data is presented as quarterly volume (cubic metres) data on deliveries in the UK.

3.2 Concrete roofing tiles survey

Concrete roofing tiles data is collected by ONS using a panel of 7 sites. This survey is voluntary, and currently, the data provided by ONS is subject to imputation by DBT in order to estimate the data for a number of persistently non-responding sites.

Further details of the survey can be found on the ONS website.

3.3 Ready-mixed concrete survey

RMC data is collected and compiled by the Mineral Products Association (MPA) and provided to DBT. RMC sales volumes are collected monthly from MPA member sites, and used to estimate whole UK market volumes. This data is sent to DBT on a quarterly basis.

3.4 Seasonal adjustment

On the same basis and using similar methods as described for sands and gravel, seasonal adjustment is applied to total RMC deliveries. The methods used for seasonal adjustment are reviewed annually, and a different specification file is used than for sand and gravel.

4. Slate

4.1 Type of data

Slate data is presented as volume (tonnes) data on production, deliveries and stocks of slate products in Great Britain on a quarterly basis. The data is split into a number of slate categories:

• roofing
• cladding and other
• powder and granules
• waste slate for fill

4.2 Slate survey

Slate data is collected by ONS using a quarterly voluntary survey of slate producing sites. Due to a declining number of slate production sites, a number of slate results have been subject to suppression and non-publication for disclosure control purposes.

The slate survey currently has a sample size of around 10. Further details of the survey can be found on the ONS website.

4.3 Disclosure control

In order to prevent sensitive business data being published, disclosure control algorithms are applied by DBT, with disclosive data points being suppressed.

5. Cement and clinker

5.1 Type of data

Cement and Clinker data is presented as annual volume (tonnes) data on production, deliveries and imports/exports of cementitious materials in Great Britain.

This data is split into the following categories:

• production of cement and clinker
• sales of cement and other cementitious materials
• total imports of cement and other cementitious materials

While exports of cement produced in Great Britain are still reported in the data tables, this data has not been reported since 2015.

5.2 Cement and clinker survey

Cement and clinker data is collected from all 4 cement and clinker production firms in Great Britain, compiled on behalf of MPA by a consultant. This data is then provided to DBT on an annual basis.

6. Bricks

6.1 Type of data

Brick data is presented as volume (number of bricks) data on production, deliveries and stocks of bricks in Great Britain on a monthly basis.

This data is broken down into different categories of bricks:

• commons bricks
• facings bricks
• engineering bricks

In addition to GB totals, the data is also broken down into regional values for Scotland and Wales, as well as English regions.

6.2 Bricks survey

Brick data is collected by ONS using a monthly survey of brick production sites, with data for non-responding sites being imputed using figures from the previous month.

The bricks survey currently has a sample size of around 65. Further details on the survey can be found on the ONS website.

6.3 Disclosure control

Due to the disclosive nature of some of the regional values for bricks, disclosure control is carried out using table formatting. Output tables on the regional level are presented in groups of 3 regions, eliminating any possibility of disclosive data being calculated based on published results.

6.4 Seasonal adjustment

Seasonal adjustment is applied to monthly brick data using the same methods as are used for sand and gravel and RMC, with a separate specification file used for bricks.

7. Concrete blocks

7.1 Type of data

Concrete block data is reported as volume (square metres) data on production, deliveries and stocks of concrete blocks in Great Britain on a monthly basis.

This data is broken down into different categories of blocks:

• dense blocks
• lightweight blocks
• aerated blocks

In addition to GB totals, this data is broken down into the same region groups as for bricks.

7.2 Concrete blocks survey

Blocks data is collected by ONS on a monthly basis using a statutory survey of blocks production sites. Similar to bricks surveys, non-responding data is imputed based on previous responses from that site.

The concrete blocks survey currently has a sample size of around 70. Further details of the survey can be found on the ONS website.

7.3 Disclosure control

Disclosure control is done to blocks on a similar basis as for bricks, with regional data aggregated to prevent disclosive data being published.

7.4 Seasonal adjustment

Monthly deliveries of concrete blocks are seasonally adjusted using the same method as other seasonally adjusted products, with a separate specification file for concrete blocks.

8. Additional information

8.1 Data processing methods

All data processing done by DBT prior to publication is carried out in the R programming language using open-source modules. Data storage and management is carried out using Structured Query Language (SQL) databases.

8.2 Response rates

Response rates for these surveys vary with time and survey. The table below shows the average response rate for each survey from December 2023 to November 2024. Response rates for a particular edition of the publication are reported each month in the release commentary.

Survey	Avg. Response Rate
Sand/gravel: land	76%
Sand/gravel: marine	88%
Roofing tiles	66%
Slate	92%
Bricks	97%
Blocks	89%

9. Glossary

Disclosive: Data which cannot be published due to data protection policies.

GB: Great Britain (England, Scotland and Wales)

10. Department for Business and Trade

The Department for Business and Trade is an economic growth department. We ensure fair, competitive market rates at home, secure access to new markets abroad and support businesses to invest, export and grow. Our priorities are the Industrial Strategy, Make Work Pay, the Trade Strategy and the Plan for Small Business.

11. Legal disclaimer

Whereas every effort has been made to ensure that the information in this document is accurate, the Department for Business and Trade does not accept liability for any errors, omissions or misleading statements, and no warranty is given or responsibility accepted as to the standing of any individual, firm, company or other organisation mentioned.

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