New guidance on low sightline IGUs

The Saveheat Group has published new guidance on the specification of low sightline narrow cavity insulating glass units.

Uploaded to member company Blairs Windows’ website, the advice covers the law, the advice of the GGF, technical notes, safety, security, and the roles Historic Environment Scotland and Historic England have to play in the specification of glass units.

Blairs Windows said there is a lack of understanding among those involved in the specification of low sightline narrow cavity insulating glass units when renovating or replacing traditional sash and case timber windows in listed buildings and conservation areas.

“The confusion around this matter results in the installation of sub-standard non-compliant IGUs in consumers’ homes and public buildings that are prone to failure within a relatively short period of time,” the company said. “This information bulletin is issued in order to clarify the true position.”

The company said the only EN1279 (and consequently CPR) compliant low sightline IGU with a 4mm cavity available in the UK has an 8.5mm sightline and is only available with aluminium spacer bar.

“No 4mm cavity IGU with a sightline lower than this – eg, 5mm, 6mm, 7mm or 8mm – has passed the required tests, and is therefore non-compliant and should neither be specified nor placed on the market,” The bulletin said.

Blairs said that a glass supplier was jailed last year for passing off standard laminated glass as fire rated glass, which was reported by the BBC.

“This same practice is occurring daily in the UK, with illegal heritage units being placed on the market by unscrupulous suppliers,” it said. “These are then specified by unsuspecting or unaware specifiers, so they continue to be produced. Some of the offending companies are also guilty of misrepresentation of certification by providing test evidence for completely different products. As well as working closely with our customers to ensure best practice and quality, we also try and attempt to work with industry federation bodies to support the elimination of the unethical element of the market.

“It’s time the industry pulls together to make a stand against non-compliance. So many manufacturers out there are working hard producing quality, compliant products it’s completely unfair that those who don’t, continue to trade. Don’t turn a blind eye and let the bad practice continue, shout about it, report these firms and let’s eliminate it once and for all.”