Why 150mm wall cavities are becoming the new normal

The construction industry is always changing. Whether through new regulations, evolving needs, or trends in best practice – specifiers must adapt. One such change is the shift towards building wider cavity walls in new homes – a survey of housebuilders revealed 41% of participants have already made the switch to 150mm.* Here are the three most important reasons to start designing with wider cavities:

1. Real world thermal performance
   Wider cavities give you the flexibility to use insulation materials that are easier to install correctly, helping to achieve real world thermal performance. Glass mineral wool, for example, can be friction fitted and will adapt to any minor irregularities in the substrate, giving a snug fit that reduces air gaps for improved thermal efficiency. Real performance will continue to be a high priority for housebuilders with the expected introduction of the Future Homes Standard next year.
2. Non-combustibility
   Building Regulation guidance around fire safety is becoming stricter, as are requirements from local authorities, insurers and other third parties. Using 150mm cavities enables you to specify non-combustible insulation for additional peace of mind. DriTherm® Cavity Slab 32, for instance, has the best possible Euroclass A1 reaction to fire classification.
3. Carbon reduction
   While reducing operational carbon is crucial to achieving net zero, the construction industry is already turning more attention to embodied carbon – the emissions released in producing a building (from things like raw materials and transportation). These emissions are projected to make up roughly half of all construction emissions over the next thirty years. Designing with a wider cavity allows you to specify glass mineral wool, which has the lowest levels of embodied carbon of any mainstream insulation material.

Despite some uncertaint

y about how regulations will evolve in the next few years, the direction of travel is clear – we should aim to create homes that are comfortable, safe, low-carbon, and affordable to run. 150mm cavities are fast becoming part of this new normal.

Access free resources on Part L and the wider housebuilding sector at Knauf Insulation’s Housebuilders Hub.