Eve’s protector trays, important if not essential!
The simplest things seem to slip people’s memory and yet are often the cause of major problems at a later date. For many years, all the best trade literature, specifications and roof tile recommendations have stated, or shown, that a support for the underlay at the eaves is essential. But I still see lots of new roofs with no adequate eaves tilt fillets.
But why do you need an underlay support board or fillet at the eaves?
Some of the many reasons are to collect condensation that forms on the underside of roof tiles and prevent it dripping back into the roof; prevent wind driven snow from being blown into the roof and to keep the building dry until the last ridge tile is fixed during construction. In each case the water that collects on the underlay will want to drain down to the lowest point, which should be the gutters, unless something prevents its progress, like a lack of an eaves tilt fillet.