Structural floor loadings for walk on glass rooflights should be stated as Uniform Distributed Load (UDL) and Concentrated Load.
Although you should expect a manufacturer or supplier to confirm what loadings the glass is designed to withstand, you should not expect them to provide information on the loadings themselves; this remains the responsibility of the specifier.
For example, if you are working on a scheme that involves a glazed floor section in a commercial shopping centre, you must provide the loadings that are relevant to this specific application in accordance with British Standards. The supplier will then ensure that the glass provided will meet those demands.
In order to establish what these loadings might be you should refer to BS EN 1991-1-1:2002, Eurocode 1: Actions on structures which covers General actions, densities, self-weight, and imposed loads for buildings.
Further information regarding UK specific loadings can be found in the UK National Annex to Eurocode 1 (NA to BS EN 1991-1-1-1:2002).
The loadings for any glass rooflight designed for deliberate foot traffic will depend on building type and specific use, but typically you might expect to see load capacities of the following magnitude:
Uniformly distributed load (UDL) from 1.5kN/m2
Concentrated load from 2.0kN
Uniformly distributed load (UDL) 4.0kN/m2
Concentrated load 3.6kN
Heavy duty commercial applications
Uniformly distributed load (UDL) 5.0kN/m2
Concentrated load 4.5kN
Glass specifications for walk on rooflights
For walk on specification rooflights the outer pane of glass should always be both toughened and laminated. It should be specifically designed for the pane size and method of support.
Typically the outer pane will be between 30-40mm thick and usually comprise of three leaves laminated together; occasionally an additional sacrificial layer of annealed glass is used on the surface.
The increased thickness of this type of glass results in a heavier product when compared with non-walk on rooflights and consideration should be given to the supporting roof structure and site logistics. Weights may typically range from 95 kg/m2 – 110 kg/m2.
To find our more about specifying rooflights book a CPD which would be delivered by a member of our expert technical team.