How Does Ice and Water Shield Work?
Ice and water shield is used at roof edges, valleys, chimneys, skylights and other places where water slows down, backs up or concentrates before draining off the roof.
Unlike standard underlayment, ice and water shield sticks directly to the roof deckComponents - A roof deck is the structural surface connected to a building’s framing that supports the roof system installed above it. More. When nails or fasteners pass through it, the material grips tightly around the hole, helping block water from following the fastener into the decking below.
This is why ice and water shield is commonly required in vulnerable areas of the roof. It does not replace metal flashing or drainage, but it adds waterproof redundancy where water is most likely to infilttrate.