The Plumbing & Heating Merchant Index (PHMI) is a brand of the Builders Merchants Federation (BMF). Developed, managed and produced by MRA Research, it uses sales-out data from GfK’s Plumbing & Heating Merchants Panel.  The PHMI provides reliable data, and a platform and voice for this important industry and for leading plumbing and heating brands to communicate to the wider market. For more information scroll down and click on the relevant links.


This PHMI uses data from GfK’s ground-breaking GfK’s Plumbing & Heating Merchants Panel, which analyses data from specialist Plumbing & Heating Merchants throughout Great Britain accounting for around £3bn and representing over 80% of total value sales to this market.  There is no overlap or double counting between PHMI and the Builders Merchant Building Index (BMBI) sales data.

GfK’s Plumbing & Heating Point of Sale Tracking Data is a gold standard in reliable market trends. Unlike data from sources based on relatively small samples or estimates, or sales from suppliers to the supply chain, this up-to-date data is based on actual sales from specialist plumbing & heating merchants. It is, in effect, the market.

PHMI trend data is indexed on the 12 months of 2019. Currently, data is available by total monthly value sales and the series tracks what is happening in the plumbing and heating market month by month. This trend series gives the industry access to far more accurate insights than has been available.


Measuring the level of RMI (Repair, Maintenance & Improvement) work in the economy is hugely important to everyone including Government. Yet prior to the development of the BMBI and now PHMI there were no decent measures of RMI, or even an approximation of it.

The PHMI and BMBI are the only reliable measures of RMI building activity in the UK. Filling an important gap, BMBI is widely used in construction, and by economists, Government, national media commentators and influencers outside the industry. The latest Monthly Construction Update from the Department for Business, Energy & Industrial Strategy includes BMBI as one of its sources.

The PHMI is an important development from BMBI, providing accurate data on a national scale on another significant part of the market. The aim is that PHMI will achieve the same level of reach and exposure as BMBI as it builds awareness and understanding of this specialist market and leading brands within it  – a pivotal reason for developing the PHMI.

The Builders Merchants Federation

The Builders Merchants Federation is the only organisation that represents and protects the interests of Merchants and Suppliers to the building materials industry in the UK and Ireland:

  • With Central and Local Government throughout the UK and in Europe
  • With enforcement bodies like trading standards and planning departments
  • The BMF will act on individual members’ behalf in disputes and keeps members up to date on current business issues
  • The BMF is the primary provider of industry specific and specialist training for all employees covering everything from apprenticeships, through product and selling skills, to manager development and even a foundation degree
  • The BMF provides a range of services to assist members in running their businesses more efficiently

Total membership from 1st September 2021 stands at 770 merchant and supplier companies who together have combined sales of over £39bn and employ over 207,000 people in the building materials industry.

BMF’s 395 merchant members operate from over 5,750 branches across the UK and Ireland.


GfK is the trusted source of relevant market and consumer information that enables its clients to make smarter decisions.

More than 13,000 market research experts combine their passion with GfK’s long-standing data science experience. This allows GfK to deliver vital global insights matched with local market intelligence from more than 100 countries.

By using innovative technologies and data sciences, GfK turns big data into smart data, enabling its clients to improve their competitive edge and enrich consumers’ experiences and choices. Learn more

The GfK Plumbing & Heating Merchants Panel:

GfK’s data sample represents over 80% of total value sales to this market. The panel includes national, multi-regional and regional merchants such as City Plumbing, Graham, James Hargreaves Plumbing Depot, Plumbing Trade Supplies and Wolseley.

This PHMI report provides valuable top-level indices but there’s considerably more data available. GfK insights go much deeper and can quantify market values and drill down into contributing categories, tracing product group performance, to focus on aspects that are critical to you.

GfK can produce like-for-like market comparability tailored to the requirements of an individual business. Merchants or suppliers who are interested in acquiring data or getting involved should contact Emile van der Ryst at emile.van-der-ryst@gfk.com.

MRA Research

MRA Research is one of the UK’s longest standing research and insight agencies specialising in construction, building materials and home improvement markets. Research services include continuous and one-off customer satisfaction surveys, brand mapping & positioning, competitive advantage surveys & competitor reviews, new product development, concept testing, advertising & messaging and decision-maker research, product usage surveys, and market tracking. For more information, including MRA’s experience and credentials, visit www.mra-research.co.uk.