Working environment

Safety of Rooflights

CWCT Technical Note 42 (TN42) was a recommended assessment method devised by the CWCT (Centre for Window and Cladding Technology) with regard to impact and fragility testing for glazed roofs.

• TN66 & TN67: supersede TN42
• TN66: describes the classification of the fragility of the glass roof assembly
• TN67: is the testing and assessment methodology to establish compliance

VITRAL has tested the modular flat Skyvision roof glazing system to this methodology to meet these safety standards.

Soft body and Hard body tests are intended to simulate the effect of a person falling on the rooflight surface and simulate the effect of impacts that might arise from tools and equipment being dropped onto the rooflight.

The result:

The rooflight passes the test and the internal laminated pane stays in place. This could save the life of a person falling onto the rooflight and potentially reduce injuries to people working or positioned below.

Please note:

There is no provision or agreed test procedure for establishing the effects of time, temperature and weather on the fragility of the glazed roof assembly. Consequently, degradation of the materials and components making-up the assembly will occur which, along with poor maintenance of the glazing system (e.g. worn glazing materials not being replaced) may cause a deterioration in performance over time.¹

It is well known that over time, UV degradation and/or surface scratches can affect the fragility of plastic based skylights, jeopardising the long term safety performance of the roof covering. This means that a rooflight specified and fitted safely, may degenerate and soon become a hazard.

Many modular rooflights do not meet the CWCT Impact resistant safety standards of TN42/66/67.

Since the rooflight products that do meet these standards use stronger more robust, tested and verified materials, they tend to cost more money.

We strongly recommend that specifiers insist on this impact safety standard to reduce the likelihood of death or injury caused by falls.

This is a point for the architect/specifier, main contractor/purchaser and the building owner/user to be aware of, since:

The Work at Height Regulations 2005 apply to all work at height where there is a risk of a fall liable to cause personal injury. They place duties on employers, the self-employed, and any person who controls the work of others (eg facilities managers or building owners who may contract others to work at height) to the extent they control the work².

¹ Extract from CWCT, Technical Note 67

² Extract fromHSE, The Work at Height Regulations 2005