Neil Hargreaves BMBI Expert for Mineral Wool Insulation: Quarter 4 2023

By Knauf Insulation
February 06, 2024

Usually, I begin with a word on the numbers. A general view, and a more granular look at some of the data that relates to mineral wool insulation.

Merchants don’t need me to make any observation about the macro-economic picture this quarter, so instead, I’d like to focus on a different number. One that I expect to have a significant impact on insulation demand now and in the near future. That number is 150.

Let me explain. In December, the UK Government published its latest consultation on the Future Homes Standard (FHS). Just over a year ahead of its proposed adoption, we’re now gaining a clearer sense of what the new standard is likely to entail. Not much change to thermal performance values, but significant change in how those values translate to compliant homes (through a new government software tool to calculate thermal performance and proposed real performance testing).

The FHS changes come, of course, mere months after the end of the transition period to Approved Document L 2021 (ADL21). Fresh off the back of adapting to the latter, the industry must now begin to prepare for further imminent change. That’s the context driving a shift in norms for newbuild homes, with housebuilders large and small increasingly adopting 150mm cavities. Why? Because 150mm is the cavity sweet spot that is part of a low-risk route to compliance.

When I speak to customers taking this route, their reasons are clear: 150mm cavities enable them to achieve the optimal balance of thermal performance, sustainability, non-combustibility and build cost, to comply with ADL21 and now the proposed FHS “notional” building.

For merchants, the impact will be two-fold. Expect more queries from customers seeking advice on the right route to compliance, for which the 150mm cavity is a straightforward solution to achieve the notional building thermal performance, which most builders default to. And expect sustained and even increased demand for mineral wool insulation to fill those wider cavities as a result. There is more clarity to come on the FHS. When it arrives, Knauf Insulation will be ready to share useful insights on the implications. In the meantime, my message to merchants is simple. Bigger is better – it’s time for 150mm cavities.