The arguement that oh i would hate to be the next guy having to remove the ice and water shield couldn t you just remove the shingles leave the ice and water down and then put new ice and water on top of the old.
Ice and water shield entire roof.
Grace ice and water shield fully adhered smooth surface roofing underlayment provides best in class roof leak protection against wind driven rain and ice dams.
Both products have a separate purpose.
Ice and water shield is a great product that can be used in spots to protect the most vulnerable areas of your roof or as a whole roof underlayment to protect from ice dams water dams storms and leaking in any area of the country and any weather.
Asphalt shingles are a little bit permeable in windy conditions but not very.
Ice and water shield is a thin rubberized asphalt membrane that goes beneath the shingles of your roof typically only along the overhangs and in the valleys.
However because the modified bitumen back surface is continuous these membranes can result in a vapor barrier.
You should seriously consider using ice water shield if you live in ice dam country.
Now ice and water shield is designed to stop ice damming or water that backs up say from your gutters and getting into the roof surface.
It s typically only installed on the first leslie.
Ice and water shield the whole roof.
It can protect your home from water leaks caused by ice dams and wind driven rain.
Potentially covering an entire roof with ice and water protector can prevent leaks even after high wind conditions blow shingles off the roof preventing further damage and making repair easier.