What’s the difference between non-fragile and walk on rooflights

Terms such as ‘man safe’, ‘walkable’, ‘walk on’ or ‘non-fragile’ are often used in the construction industry, but these terms should be treated with caution and the specifier should understand the difference when looking to install this type of product.

Firstly, all walk on rooflights must be manufactured using glass. GRP or Polycarbonate materials can never be classed as structural walk on rooflights designed for deliberate foot traffic.

A non-fragile rooflight is not designed to be walked upon and is only designed to save lives by preventing people or objects falling through it accidentally when accessing roof areas not designed for regular foot traffic.

Non-fragile rooflights have several different classifications. Class 1 describes glass designed to be used for occasional maintenance or cleaning which will support the weight of people and any equipment without the glass breaking; class 2 describes glass designed not to be walked on but is required to be non-fragile in the event of a maintenance person falling on the surface, where the glass will support the initial fall but may become damaged.

You can read about further classifications regarding non-fragility in rooflights in our blog post ‘How does non-fragility affect glass rooflight specification?

With walk on rooflights, the most important fact to remember is that walk on products are designed to structural floor loadings which are much higher than roof loadings. Manufacturers of this type of product should be able to provide loadings that the glass is designed to withstand. This information is covered in our post on ‘Structural floor loadings for walk on glass rooflights’.

To read more about understanding the differences between ‘non-fragile’ rooflights and ‘walk-on’ rooflights for deliberate foot traffic please read NARM Technical Document NTD11 issued in February 2015.