Protective ice and water membranes work well for flashing and help protect around skylights, dormers, turbines and other complicated areas of the roof. The valleys can be open or closed: the open valleys are not covered with tiles, but the valleys are closed. If your roof will have open valleys, something IKO recommends, now is when the valleys must be lined with a wide preformed, corrosion-resistant metal. My roof has an ice shield to prevent ice from forming at the edges and accumulating under the roof. In addition to avoiding foot traffic on roof tiles, it's best to do it from top to bottom if the roof is steep enough that cats and boards are required to walk on it.
It works really well. I've been making roofs this way for years, not as fast as if the roof were knocked down, but you get a more durable roof and you can do it with just one person, John Runyon, an old carpenter from 1145 from the European Union. Although this seems to contradict the principle of superposition, installing the dripping edge on the base of the rakes creates a clean edge on the roof and provides the subfloor support with greater resistance against wind uplifts. If you are going to lay roof tiles, you could also do everything you can to ensure that the roof covering doesn't come off when the strong wind blows.
The roof tiles are nailed with galvanized nails (at least mine are) and in the few roofing jobs I have done they have used a nail gun to nail the tiles through the roof felt and the plywood. Most catastrophic roof failures during storms occur because the plywood coating of the roof comes off the beams and frames. It literally provides a clean, sharp edge from the start of the roof and protects the lower edge of the roof from water damage by preventing water from “defying gravity and receding” before leaving the roof. The 250 mm (10 inch) length is folded in half so that 125 mm (5 inches) reaches the wall surface and the other 125 mm (5 inches) extend to the roof cover.
Asphalt roof tiles are the visible part and the first line of defense against inclement weather, but what's underneath them really counts.
