Ice and Water Shield
What is ice and water shield and where is it installed?
Ice and water shield is a self-adhering rubberized asphalt membrane applied directly to the roof deck. It is installed at eaves, valleys, penetrations, and any low-slope transitions where water is most likely to pool or back up. The membrane seals around fastener penetrations to prevent moisture migration.
Does Southern California need ice and water shield if there is no snow?
Yes. The membrane protects against wind-driven rain, not just ice dams. Heavy California rain events push water uphill under panel seams through capillary action. Ice and water shield at eaves and valleys creates a failsafe barrier that catches any moisture that bypasses the primary underlayment layer.
How does self-sealing work around fastener penetrations?
The rubberized asphalt compound in the membrane reforms around any fastener that penetrates it. When a clip screw passes through the membrane into the deck, the asphalt closes around the screw shaft and creates a watertight seal. This self-sealing property is what makes it critical at every flashing transition point.