Silicone-sealed glazing and rooflights

Abstract

While capped systems, described in the previous section, suit pitched roofs, they cannot reliably be used on (nominally) flat roofs, where the roof pitch is usually 3° to 5°. This is mainly because the rainwater running down the roof cannot pass the horizontal glazing bars which project above the surface of the glass. The smooth, continuous finish required for flat glazed roofs is achieved with a silicone seal between glass panels that is set flush with the surface of the glass. The glass is clamped in place with short lengths of pressure plate that are recessed below the outer seal. The recessed plates are secured to an aluminium channel which forms an integral part of the double glazed unit and which is continuous around its perimeter. The extruded aluminium channel is recessed into the gap at the edge of the unit usually used to bond the unit together and to seal the edges behind the spacer.