What is Ice and Water Barrier and How Is It Used?

Ice and Water Barrier is a thick 60 mil +/- self adhering asphalt-based membrane that is designed to provide a highly waterproof barrier on or around critical areas of your roof. There are four main areas on your roof that Ice and Water Barrier is typically placed.

Eaves – the horizontal edges of your roof. This is where you hand your Christmas lights. Picture?

Valley – where two pitched slopes meet and create a channel for water to flow off the roof, you could think of them like gutters on the roof, they collect all the water from the two slopes and direct it off the roof. Picture?

Roof to wall transitions – areas where a pitched roof surface meets a vertical wall surface. The most common place this is found is on a multiple level home where there is a roof surface that meets a second or third story wall. Picture?

Roof penetrations – anything that protrudes past the plain of the roof surface. Probably the most common form of this is a plumbing vent pipe. Picture?

Why is it important and how is it used?

Eaves are the areas where your roof may be susceptible to ice damming in the winter months. Ice damming is the result of a warm roof surface melting the snow on it, that snow turns to water then travels down the roof to the eave where it hits the cold air and freezes. This process will continue and will melt and freeze layer by layer creating more and more ice which slowly moves up the roof. Eventually that water will pool behind the ice and will stay in liquid form and work its way underneath the shingles. If Ice and Water Barrier is not present then that water will work its way into the plywood sheathing and eventually inside your home, showing its ugly face as a water spot on the ceiling, or worse, as a waterfall in your home.

Some locations have building codes that require Ice and Water to be placed directly against the wood sheathing along the eaves and up the roof past the interior warm wall to prevent the intrusion of water. Even if it is not required it is always a wise investment to add when you are having your roof replaced if you live in a climate that experiences snow.

Valleys are critical areas on your roof where Ice and Water can be used to add an additional layer or protection. A high volume of water flows through these areas, which causes this area of the roof to deteriorate at a quicker rate than the rest of the roof. The water volume and the increased deterioration plus the affinity to debris such as sticks and leaves from surrounding vegetation makes these areas more susceptible to leaking and thus the reason for adding the additional protection of Ice and Water Barrier. Most locations have building codes that require some sort of valley liner, Ice and Water Barrier fulfills that requirement and so is placed right against the wood sheathing in the valley and is then shingled over.

Roof to Wall Transitions are susceptible to water leaks because all the water from the vertical surface falls directly at the junction of the pitched roof surface. There is a high volume of water all congregating to one location where the flow of water is interrupted by a change in direction. If this area is not flashed, or waterproofed properly, that water can continue to travel down the vertical plane and enter your home causing significant damage. Ice and Water Barrier is used to bridge the gap between the vertical wall plane and the roof plane. On top of this, metal flashing will be placed to ensure this area of your roof is waterproof and no leaks occur.

Roof Penetrations are protected using boots or jacks. These are comprised of a flexible rubberized material that hugs the penetration and a metal piece that is nailed to the roof surface. Ice and Water Barrier can be used in this situation to flash on top of the uphill side of the pipe jack so that water cannot enter from the slope above. If water did get under the shingles above, it would run on top of the ice and water and then on top of the metal portion of the pipe jack and out on top of the next course of shingles, thus preventing a leak.