Steel framed glazed windows can be designed and installed to protect life and property in the event of fire. Combining the transparency of glass with fire safety is a challenge that demands high standards of construction, which is then independently tested and assessed by recognised competent authorities.
Some of the standard window ranges have been examined by Warrington Fire Research (reports available upon request) to meet such standards. These are illustrated in the datasheet below, which summarises key features of construction, indicates a variety of appropriate glass types and gives pointers to their scope of application. West Leigh uses hot-rolled profiles from the SMW, W20 and W40 ranges to provide fire-resistant glazed fixed windows, which will maintain their integrity in a typical fire for 30 or 60 minutes.
Glazing systems are tested in accordance with BS476: Part 22: 1987 - 'Methods for determination of the fire resistance of non-load−bearing elements of construction' and are assessed on their ability to satisfy the performance criteria referred to in paragraph 7.6.1: 'Integrity and Insulation'. The integrity criterion is satisfied when, for the required duration, a test specimen neither collapses nor develops cracks or apertures through which can pass flame or hot gases.
When fixing windows, perimeter fixings must be no more than 150 mm from corners and a maximum of 450 mm (30 minutes integrity) or 250mm (60 minutes integrity) from centre to centre. Fixings should penetrate through the frame and be affixed to good structural openings of either brick, block, concrete masonry or steelwork which should have both stability and integrity greater than the window frame. Should lugs be required to fix the windows, these should be at least 25 mm wide x 2 mm thick steel.
All fire-resisting glazing is to be set onto non-combustible setting blocks and secured by cold-formed 0.6 mm thick steel channel beads which are snapped over steel mushroom-head studs and finished with corner cover clips. All studs must be placed at a maximum of 75 mm from the corners and a maximum of 300 mm from the centre. Ceramic or mineral fibre tape is to be placed either side of the glass edge and is to be capped with intumescent silicone or acrylic sealant.