What is ice and water shield?
A self-adhering waterproof membrane installed at the eaves, valleys, and other vulnerable roof areas to seal out water that backs up behind ice dams.
Ice and water shield is a rubberized asphalt membrane applied directly to roof sheathing before shingles go down. The material bonds itself to the wood without nails or fasteners and creates a watertight barrier that stays flexible in cold weather. Its primary job is to stop water from leaking through the roof deck when ice dams form at the eaves or when heavy snow melts and refreezes, pushing water backward under the shingles.
In Hartford Metro and across Connecticut, ice and water shield matters because winter conditions regularly create ice dams. When gutters clog or heat escapes from the attic, the roof edge stays cold while melting snow higher up pushes water back toward the fascia. Without protection, that backed-up water finds its way into the attic, walls, and ceilings. The shield catches it and directs it back down over the edge.
Connecticut building code requires ice and water shield in two locations: along the eaves (typically 24 to 36 inches up from the roof edge, depending on local frost conditions) and in valleys where two roof planes meet. Some contractors extend it further onto low-slope sections or around skylights for extra protection. The membrane is installed as part of the roofing system before the underlayment and shingles, making it a preventive layer rather than a repair after the fact. When budgeting a roof replacement, ice and water shield is a line item that pays for itself by avoiding water damage.