VIEWPOINT
WHAT THE WARM HOMES PLAN MEANS FOR MERCHANTS Matt Neary, sales director Knauf Insulation
THE GOVERNMENT HAS launched the Warm Homes Plan, backed by £15 billion of funding over three years, to support millions of households with retrofit projects. Measures covered include insulation, solar panels, battery storage and heat pumps, all aimed at cutting fuel poverty and reducing reliance on fossil fuels. While the BMF broadly welcomed the plan, it criticised the government for not making insulation a mandatory prerequisite for access to heat pump grants. That raises an important question for builders’ merchants. What does this mean for those stocking insulation?
Insulation still matters Despite these concerns, the Warm Homes Plan will continue to drive demand for insulation. The plan explicitly recognises that well insulated buildings are essential for improving health outcomes, cutting emissions and delivering year-round thermal comfort. Landlords will also be expected to upgrade properties to a minimum EPC C rating by 2030, reinforcing the focus on fabric performance.
Enabling low carbon technologies
One of the clearest signals in the Warm Homes Plan is the scale of ambition around low carbon heating. Heat pumps in particular are expected to play a growing role, but they are not a standalone solution. Heat pumps perform best in buildings with low heat demand. Without adequate insulation, systems may need to be oversized or run at higher flow temperatures, reducing efficiency and increasing running costs for homeowners.
The plan places strong emphasis on retrofit and on measures that represent good value for money and deliver maximum impact. It notes that by the end of 2024 around 71% of British homes had cavity wall insulation, with a further 10% fitted with solid wall insulation. While this represents real progress, the government argues it also highlights the scale of the remaining opportunity.
For merchants, the message is straightforward. Core insulation
products that already underpin retrofit activity will remain in strong demand.
Lofty ambitions A significant proportion of the UK housing stock still has inadequate loft insulation by modern standards. Topping up or replacing loft insulation remains one of the most cost effective and immediately impactful upgrades a homeowner can make, and the Warm Homes Plan clearly supports this approach. Glass mineral wool loft insulation is widely understood to be efficient and relatively simple to install correctly. Approved Document L sets out a maximum U-value of 0.16 W/ m²K for roofs in new residential buildings, which can typically be achieved with around 270mm of loft insulation. However, where space allows, increasing depths to 400mm or even 500mm can deliver further benefits, reducing heat loss and thermal bridging while maximising value for money.
This reinforces loft insulation as a continued priority for retrofit programmes and a dependable category for merchants.
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This is why insulation remains a practical prerequisite, even where it is not formally mandated. Merchants who understand this relationship will be better placed to support installers and local authorities delivering projects under the Warm Homes Plan at scale.
What this means for merchants
For builders’ merchants, the key takeaway is continuity. The Warm Homes Plan does not signal a move away from established insulation products. Instead, it reinforces their importance. Glass mineral wool loft insulation and other familiar staples will continue to form the backbone of retrofit activity. They offer strong value, proven performance and compatibility with emerging technologies.
Merchants that stock the right
products, understand the role of fabric efficiency and can advise customers with confidence, will be well positioned as the plan gathers momentum. Policy framework may evolve, but physics does not. Insulation remains the starting point for warm, efficient homes, and demand will continue across the supply chain for years to come. BMJ
www.buildersmerchantsjournal.net March 2026
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