Worst House on the Street

A renovation project featured on Channel 4’s Worst House on the Street (16 April 2025) has demonstrated the energy-saving potential of ROCKWOOL® stone wool insulation. Friends Bradley Dodic and Billy Parsons took a fabric-first approach to modernise their 1930s semi-detached home in Exhall, Warwickshire, resulting in improved thermal comfort, enhanced acoustics and a marked uplift in energy efficiency.

Faced with rising energy costs and a house in need of complete renovation, the pair prioritised insulation as a core component of their build strategy. “I wanted to find a manufacturer who had a range of products we could use across the whole house. There’s no point in having a really warm extension and the rest of the house be freezing. I also wanted to use insulation from a company that is sustainable,” added Billy.
“ROCKWOOL insulation was one of the products we looked at, and two things stood out to me,” Brad continued. “First was how sustainable they are as a business. And secondly, their technical service team were really helpful by supporting me through the entire process.”

To improve the thermal envelope of the new extension, Brad and Billy specified 150mm of NyRock® Cavity Slab 032, used alongside plasterboard on dabs to help meet a minimum U-value of 0.18 W/m²K. NyRock Cavity Slab 032 is BBA certified and developed using patented NyRock technology, offering a low thermal conductivity of 0.032 W/mK. This allows the required thermal performance to be achieved with a thinner profile than standard stone wool alternatives .

Now complete, the home has achieved a notable uplift in energy performance. Concluding, Billy added: “Since finishing the house, we’ve had a further SAP [Standard Assessment Procedure] assessment, and we’ve gone from a low D to two marks off a B.”

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