Why triple glazed rooflights should be avoided!

Published: 14th November 2022

Sounds great doesn’t it, triple glazed rooflights! Great for energy efficiency, sound insulation etc etc.

Unfortunately it’s not as simple as that. According to recent articles including from ‘Glass Times’ the industry’s leading trade journal,

‘Do a growing number of centre pane failures in triple glazed IGU’s (Insulated Glass Units) represent a ticking time bomb for the UK’s window industry’.

And this article is for normal triple glazed windows and not rooflights. Roof windows are subject to a lot more wind/ rain/ ultra-violet attack than a simple house window as you can well imagine.

In fact we have changed a lot of triple glazed rooflights throughout the UK. And it’s almost always exclusively the centre pane that fails. A common occurrence of triple glazed rooflight failure is from the many, many new companies selling ‘stick on no frame’ cheap triple glazed rooflights imported from China and Turkey.

Firstly, it is only logical that two window seals will fail at twice the rate as single seals on double glazed rooflights albeit it’s actually a lot more. Secondly, it turns out that many companies’ use ultra thin 4mm glass as the centre pane which is just plain daft. The centre pane suffers from more heat build up/ thermal stress and there is thus a higher failure rate of the centre pane (as we have seen time and time again). We have changed many, many rooflights from a company called Roofmaker and its always the centre pane and Roofmaker do not warranty against glass breakage. We have noticed they have switched from triple glazed rooflights as standard to now instead pushing double glazed rooflights (see their reviews to understand).

Another issue particularly with cheap ‘stick-on’ glass only rooflights ‘is the quality of the glass cutting. The edges of the glass on cheap units is always poorer and poorly cut glass will lead to failure of, often, the centre pane. In our opinion these cheap ‘stick-on’ triple glazed rooflights are a definite ‘no no’.

Also the truth is that with double glazed rooflights you can buy ‘coatings’ on the glass that will give you a UD-value as low as 0.9 which in essence is about the same as triple glazed rooflights so from an environmental perspective it takes a lot less energy to manufacture and transport high quality double glazed products than heavy, high energy consuming triple glazed skylight products.

Also normal glass has a ‘green tint’ to the glass which becomes a lot more obvious with triple glazed products than double glazed products. One benefit of triple glazed products is noise reduction but if you live in an area of high noise you would simply add a laminated inner sheet to give you better acoustics than triple glazed products.

So if the heat loss values are almost the same it is better to invest in the best coated low UD-Value rooflights than the comparable triple glazed rooflights. This is why we only warranty triple glazed rooflights for 5 years whereas our amazing Blade rooflights come with a ‘lifetime warranty’.

We always supply the best possible energy efficient coatings available which cost more money than cheap coatings and the difference is so minor between triple glazed vs high quality double glazed it just makes sense to invest in high quality silicone sealed low UD value products than poor quality Turkish and Chinese stick on glass products for long term reliability.

And buying ‘no frame’ glass only products well that’s another whole discussion… Please read our blog online ‘Don’t buy frameless rooflights’ at ofset.co.uk.

Choose your Rooflight products wisely. Rooflights should be forever and thus our incredible ‘lifetime warranty’.