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Tue June 25 2024

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Steni asks whether it be nobler to clad

25 Aug 11 The BBA’s recent announcement of its support for the mass rollout of Solid Wall Insulation (SWI) to meet the Government’s climate change targets is going to leave housing specifiers in a quandary, according to cladding manufacturer Steni UK.

They will be faced with two options – whether to stick with tradition and weather that insulation with render or to try a “Modern Method of Construction” and opt for rainscreen or rear-ventilated cladding systems that have actually proved themselves over the centuries in Scandinavia.

The BBA’s agreement to work with the Solid Wall Insulation Guarantee Agency (SWIGA) and the National Insulation Agency (NIA) will involve the BBA conducting an initial assessment of installers’ competence to survey properties and subsequently the decision made on which solid wall system is best for the job.

This assessment and surveillance scheme will cover external and internal wall insulations and hybrid systems which combine both on the same property.

The initiative forms part of a SWI industry framework developed by the NIA and SWIGA to bring about a tenfold increase in SWI capacity in a controlled manner. This will support Government targets under the Green Deal and the recommendation by the Committee on Climate Change that around 2.3 million SWI installations will need to be carried out by 2022 to achieve Government climate change targets.

Steni warns that while render has been used as a weathering and aesthetic finish to a building since time immemorial, even technological developments have failed to qualify it as a Modern Method of Construction.

Steni UK managing director Ian Anderson says: "In fact, in the current climate of risk minimalisation, any specifier choosing to go down the render route is actually increasing the risk element on several levels.”

He explained that maintenance-wise, render degrades over time, and particularly quickly in aggressive environments such as coastal regions, then requires patching or complete replacement - a messy job. It even suffers from being cleaned. This is not the case however, with a rainscreen system that is resistant to anything the UK climate can throw at it, including airborne salt water.

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“While most building materials have a limited life, rainscreen cladding systems are designed to last more than 60 years without loss of functional effectiveness,” he said.

Environment-wise, disposing of waste render can be difficult. Specifying a rainscreen system removes this challenge as the panels are produced in the factory – in Steni’s case, to bespoke sizes - for minimal wastage on site.

Ian added: “This unique capability not only minimises waste on site but ensures quality fabrication.”

Weather-wise, render is subject to the vagaries of the British climate and cannot be applied if the weather is inclement, leading to costly delays on site and increased disruption to residents if they are already in situ. Rainscreen cladding systems are generally resistant to water, moisture, UV rays and temperature extremes, are a modern, dry trade and can be installed whatever the weather.

Aesthetics-wise, a render finish is fairly standard while rainscreen cladding systems are available in render-like aggregate finishes that include ultra-fine stone as well as smooth finishes with varying gloss levels, with both available in a variety of standard colours and almost any special colour from the NCS-, RAL- or BS- colour system.

Safety-wise, even in good weather, render creates mess on site, making it more difficult to comply with Health and Safety Executive regulations that every part of a construction site should be kept in good order. Rainscreen cladding panels are manufactured to both standard, and in Steni’s case, bespoke sizes to minimise both waste and mess on site – making it much easier to protect the workforce.

Then there are whole-life costs. Ian says: “Render may be more cost-effective than cladding to initially install but over the life of a building that temporary saving is going to come back to haunt the specifier and the client.”

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