A proposal to include build quality guidance notes in revised Part L regulations, anticipated to come into effect later this year, has been welcomed by insulation specialist Actis
The proposal has been included in the 98-page MHCLG Part L and Part F consultation document on Building Regulations for England, which forms the first step towards the Future Homes Standard, which should be in place by 2025.
The revised Part L regulations guidance notes would give practical, technical advice on how builders could address the performance gap and reduce thermal bridging, while ensuring airtightness doesn’t harm the structure of the building.
Thermal bridging to reduce CO2 loss
The document spends several pages looking at the impact of insulation gaps and the need to address thermal bridging to reduce CO2 loss.
Actis UK and Ireland technical director Thomas Wiedmer, who has worked on the company’s response to the revised Part L regulations, says construction details should get further attention within the build quality section.
Wiedmer said: “Construction detailing is one of the biggest issues causing the Performance Gap. Tying projects up with specific details used is important to close the gap between designed and expected performance and we would go even further and suggest that a registration scheme could help to drive the importance of following these details on site.”
A building with insulation which is effective on paper can still see huge heat loss of 20-30% if thermal bridging occurs. The only way to avoid such a scenario is for construction details to be thermally approved and followed through on-site, he explained.
Minimise heat loss
Actis has worked closely with the LABC to create a foolproof method by which builders can minimise heat loss in this way – and in 2019 created a new set of Registered Construction Details.
The new RCD, part of a selection aimed at helping builders achieve as-built performance, provide construction details and checklists of points to look out for during design and on site. They offer instant access to online tutorials to help them reduce heat leakage through weak junctions – the weak points of an insulated building envelope – and thus design out thermal bridging.
The details offer a combination of specific detail, good practice and points to watch, together with a range of modelled psi-values using different build ups which exceed expected industry standards.
The RCD drawings and documents can be fed into specifications for projects and are also accessible on the go.
Wiedmer added: “Energy efficiency standards should always be based on reducing the need for energy first and in particular limiting the heat loss through thermal elements – that is through achieving excellent U-values, reducing thermal bridging and improving airtightness – the fabric first principle.”
The Actis Hybrid range of insulation and membranes is designed to meet all the goals outlined in the document – and will provide ideal fabric first solutions for the forthcoming Future Homes Standard. The flexible nature of the Hybrid products means they can be bent round corners and moulded into gaps to help eliminate thermal bridging.
The Future Homes Standard 2019 Consultation on revised Part L and Part F Building Regulations for new dwellings is nearing the end of its consultation period – respondents have until 7 February to give their feedback.