What is ice and water shield?
Ice and water shield is a self-adhering bituminous or synthetic waterproof membrane applied to roof decking at eaves, valleys, and penetrations to protect against ice dam damage and water infiltration.
A self-adhering membrane installed directly to the roof deck, ice and water shield acts as a secondary barrier between the shingles and the underlying structure. In Connecticut, where winter conditions produce ice dams and freeze-thaw cycles, the membrane stops water that backs up under shingles from seeping into the attic, walls, and interior ceilings.
The material is typically applied in vulnerable zones: along eaves (where ice dams form), in valleys (where water concentrates), around roof penetrations such as vents and chimneys, and at any depression or transition that channels water. Connecticut building code requires ice and water shield in these locations on all structures to mitigate the risk of rot, mold, and structural damage that can result from winter water intrusion.
Unlike traditional tar paper or felt, ice and water shield remains tacky and forms a watertight seal around nail holes and seams. It stays adhered even as the roof expands and contracts through temperature swings, maintaining its protective function through multiple freeze-thaw cycles. Roofers typically roll or install it before laying shingles, and it remains in place for the life of the roof.
For roofing projects in Connecticut, specification and correct installation of ice and water shield are standard practice. Roofing contractors familiar with the state's climate demands understand where and how to apply it to ensure lasting weather protection.