Ice and water shield is a self-adhered membrane roofing underlayment that offers premium leak protection for sloped roofs subject to the effects of ice dams or wind driven rain. So if the purpose of ice and water shield is to prevent leaks from ice dams how can they happen? Simply put, because of a poor installation. Many times inexperienced or just plain lazy roofing contractors put the metal drip edge on the eave then on top of that the ice and water shield. Doing it that way will leave the roof vulnerable to ice dam leakage. It is vulnerable because when the gutter fills with snow and ice water can melt underneath the drip edge, creep up the fascia boards, and under the drip edge. This will cause a leak in your home because the water will go right where your roof deck and fascia board meet. That is why professional roofing contractors always apply the ice and water shield this way:
1. Clean the roof deck of any nails and debris
2. Apply Ice and water shield to deck making sure to roll it over the eave and on to the fascia about 1-2 inches.
3. On top of that install drip edge. We hang it over the roof deck and roll it right on to the fascia boards.
4. Starter Strip
5. Shingle, Shingle, Shingle,
No problems due to snow an ice will cause leaking in a roof with ice and water shield installed this way. So make sure that your roofing contractor explains the way they will install your ice and water shield.