What are eaves fillers and when should they be used?

Eaves (or bird comb) fillers are used at the eaves, where the roof slope meets the gutter. They are used when the gap underneath the laid tiles is greater than 16 mm. Eaves fillers close off this gap to prevent birds and rodents entering the batten cavity, the area between the tiles and the underlay.

Some tiles have bespoke plastic eaves filler units, however, universal eaves filler are now available which contour themselves to the shape of a particular tile.

Eaves fillers should not be confused with roof space ventilators. Roof space ventilators allow air to ventilate into the roof space beneath the underlay, whereas eaves fillers are there to prevent access into the batten cavity, ie between the underlay and the tiles/slates.