INSULATION SIMPLIFYING RAINSCREEN IN A T
he Building Safety Act (BSA) has massive implications for rainscreen specification and subsequently for merchants and distributors in England. It applies to all residential buildings, although there’s a particular focus on higher- risk buildings, described as those over seven storeys, or 18m tall that contain at least two residential units, or are used as care homes or hospitals.
Three new Gateways have ‘checkpoints’ to allow the Health and Safety Executive to assess Building Regulation compliance.
It places greater levels of accountability across the construction supply chain, with the principal designer responsible for the ‘golden thread of information’ – a digital record showing how every building was designed and built. Retrospective liability has also been increased to 30 years, so the principal designer must be confident in the materials and systems specified by themselves or sub-contractors. Feeding into the BSA are the Building Regulations, which themselves have been subject to significant updates. Approved Document B in England requires buildings to be designed and built to prevent the development and spread of fire.
In 2018, combustible materials were banned from use in all external walls of relevant buildings over 18m tall. Now, the definition of ‘relevant buildings’ has been widened, and the ban extended to include certain build- ups, such as rainscreen façade systems, of
residential buildings between 11 and 18m unless a full-scale fire test to BS 8414-1 or -2 has been undertaken.
As well as using non-combustible materials, cavity barriers must be installed to stop flame spread within the cavity. Part B requires a minimum fire resistance of 30 minutes’ integrity (E30) and 15 minutes’ insulation (I15). But some stakeholders, may require a fire resistance of up to EI120 (integrity and insulation of 120 minutes) depending on the build-up, to give people maximum time to escape and help preserve the structure. Approved Document L (Part L) in England, which governs thermal performance, has been updated. Residential buildings must now produce 31% less carbon emissions compared to the 2013 standards (27% for non- domestic). This should be delivered by fabric improvements such as insulation, and low and zero-carbon technologies.
The direction of travel is clear. Standards are
CHANGING REGULATIONS CLIMATE Specifiers are facing greater pressures than ever before, seeking solutions to new challenges. Kelly Westwood, head of construction projects at Knauf Insulation, explains what merchants need to know.
not just getting stricter but must be delivered in the real world – and responsibility for compliance lies with specifiers.
Specifiers must ask themselves: ‘Am I certain each component complies with the regulations? Am I certain they won’t interact in ways I hadn’t intended?’ If there’s even a hint of uncertainty, what advice can merchants offer customers? A good way to mitigate this risk is to use system solutions. You can now get complete rainscreen systems where cavity barriers, sheathing insulation, and fixings have been tested individually and together. Certain systems feature insulation that meets the strictest non- combustibility requirements, so are suitable for every height and use of building. Systems like these help specifiers streamline processes, whilst meeting the Building Regulations. Having the technical support provided include 3D U-value calculations is critical in ensuring accurate thermal modelling because the calculations are based on actual penetrations from the steel frame system rather than a correction factor. Essentially, calculations that ensure the finished building is more likely to deliver its ‘as designed’ performance. The Building Safety Act will have a profound effect on the way that buildings are designed, and products are specified. For merchants, that means stocking and recommending the right insulation solutions for every application and being ready to offer products that meet the relevant requirements both individually and when combined as a system. BMJ
Long Rake Spar qp BMJ
May24.indd 1
May 2024
www.buildersmerchantsjournal.net
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