Purpose of Ice and Water Shield

By Mark J. Donovan

I often get asked what exactly is Ice and Water Shield. When I first started receiving this question I was somewhat shocked that people were unaware of this roofing product. Ice and water shield has been a godsend in the housing industry for years now. It is used for protecting homes and roofs from water and ice damage and every responsible builder and roofer uses it today.

So what is ice and water shield? Simply put, it is a flexible and sticky membrane that is
placed on the roof sheathing prior to installing the shingles. This membrane seals up
leak-tight around roofing nails that puncture it. It is used mainly along the roof
edges and in the valleys, and along walls or chimneys to protect against ice dams and water seeping underneath flashing.

Ice and water shield is commonly sold in 3 foot width rolls. Typically one or two courses of it is installed along the roof eaves to achieve 3 to 6 feet of coverage. In the roof valleys it is usually positioned so that there is about 18 inches of coverage on either side of the valley. Where a roof abuts a wall the ice and water shield is typically installed up the wall 6 to 18 inches. House siding is then installed over it.

So if you are having your roof reshingled make sure that the roofing contractor includes the installation of ice and water shield in the quote.