What is an ice and water shield and why does it matter in Minnesota?
The membrane addresses our specific climate threat. When ice dams force meltwater to pool and back up under the shingles, ordinary underlayment may not stop it, but the self-sealing ice and water shield resists that intrusion at the vulnerable eaves and valleys.
Because it is installed under the shingles, it is hidden on a finished roof. An inspector evaluates the visible roof and notes the age and signs of past ice dam leaks, but the underlayment itself is confirmed at installation, not during a typical inspection.
When you replace a roof in Minnesota, ensuring adequate ice and water shield at the eaves and valleys is one of the most important details. It is a worthwhile question to raise with roofers, since proper underlayment is a key defense against ice dam damage.
