A roof should always be installed with maximum ice dam protection in mind. Most roof installations can withstand normal rain and snow, however only an expertly installed roof can withstand the most extreme weather we constantly endure in New England.
From my experience,there are always a few sections of every house that are in danger of ice damming. Sometimes, proper attic insulation and proper ventilation will help solve these problems.
However, most ice dams form from the gutters, and northern sections of the roof where snow can build up in areas of low pitch and no sunshine.These are the areas we identify and formulate a plan for maximum protection. This usually means that we will remove the gutters,and install ice shields down the fascia boards,and install some commercial grade termination bars before we re install the gutters. In problem areas, heating coils may be installed to provide additional protection. In some cases, copper valleys,pans and flashing are needed on the roof, as well as up the sidewalls.
We install, standard on all roof contracts, 6 feet of ice and water shield to insure against ice dam penetration. Chimneys and skylites also get wrapped completely with the highest grade of ice water shield. Where the ice/water shield ends, we install a synthetic underlayment. This allows proper attic ventilation,and superior adhesion of roof shingles.