When fixing a roof glazing system at the eaves (foot of slope), a gap will be created between the glazing bars. On a rafter gasket system this gap will be a similar thickness to the rafter gasket itself i.e. approximately 3mm. On a structural glazing system the gap will be around 12mm, the same height as the lower section of the base bar.
Through this gap could blow draughts, rain and obviously insects. The aluminium rail (eaves filler) is designed to be screw fitted to the eaves beam or eaves support of the structure between the glazing bars. The gasket that forms part of the eaves filler stands high and the glazing sheet rests on the gasket thereby closing the gap.
The eaves filler can also be used at the ridge end although on wall fixed applications this is not always needed as the ridge is usually flashed over, it is more common on freestanding applications.