What Is an Ice and Water Shield?

An ice and water shield is a membrane that protects your home from moisture. Although you may not know it, one of the most important parts of your roof is a layer you can’t see: the ice and water shield.

What Is an Ice and Water Shield?

Whether you choose a luxurious slate roof or a traditional asphalt shingle roof, the roof’s finish is the only visible part. Your roof has multiple layers, each of which plays a vital role in protecting your belongings, family, and home from the elements.

When professionally installed, these layers come together to form a roof system. Homeowners should understand the various components to keep an eye out for problems that require professional repair and replacement.

One of the most essential parts of your roofing system is the ice and water shield – here’s what you should know about it.

What Is an Ice and Water Shield?

The primary purpose of an ice and water shield is to protect your roof’s sheathing. Decking (or sheathing) is the layer of plywood that attaches to the joists in your roof.

The underlayment and roof finish attach to this decking. While those layers provide some protection, it’s also important to have an ice and water shield in place. Plywood absorbs water, so installing an ice and water shield on top of that plywood layer ensures that your sheathing doesn’t become water-logged.

Do I Need an Ice and Water Shield?

Certain roof areas, like valleys, need ice and water shields. A roofing valley occurs when two slopes meet to form a “valley” in the roofing. Since water flows towards these areas, having an ice and water shield under the roof finish is necessary.

Another factor determining if you need an ice and water shield is your roof’s pitch. Roofs with pitches of 2/12, 3/12, and 4/12 should have ice and water shields from one end to the other. Flatter roofs hold more water, making an ice and water shield necessary.

Also, consider the climate. Coding laws require homes above the US snowline to have an ice and water shield. The shield must run along the roof’s edge to prevent ice from damming after a heavy snowstorm.

If you live in an area that faces heavy annual snowfall, plan on installing two rows of shield to your roof’s eaves and peaks.

Three Types of Ice and Water Shield

You can choose from three ice and water shield types: granular, smooth, and high heat. Understanding the makeup of each type and how they benefit your home ensures that you make the right choice.


A granular ice and water shield has a sandpaper-like finish, much like asphalt shingles. Roofing contractors install this type of shield in roof valleys. Even though granular shields are the thinnest option of the three, they perform well, especially in areas where snowfall isn’t too heavy.


Smooth surface ice and water shields are ideal for low-pitch roofs. If your roof has a pitch of 2/12, 3/12, or 4/12, a contractor will recommend this type of shield in most cases.

High Heat

High-heat ice and water shield have cotton-like fibers that make them the thickest option of the three. This type of ice and water shield is ideal for metal roofs, especially those in areas above the US snowline.

Frequently Asked Questions (FAQ)FAQ

How much does it cost to have an ice and water shield installed?

The cost of roofing materials varies from region to region, but we can look at national averages to get a good idea of the cost of ice and water shields. Granular shield costs around $50 per 100 square feet. Smooth shield costs around $100 per 100 square feet. High heat shield costs approximately $125 per 100 square feet.

How long should my ice and water shield last?

Many types of ice and water shield come with a lifetime warranty.

Should I use ice and water shield on my entire roof?

You are certainly allowed to cover your entire roof in ice and water shield, but it probably isn’t necessary. Instead, let a roofing contractor tell you where ice and water are more likely to “pool” and have the shield installed in those areas.

Final Thoughts

An ice and water shield is integral to protecting your home from the damage caused by water and ice. Even though you can’t see this layer of roofing, it does the hard work of protecting your home from leaks.

If you’re planning to have a new roof installed on your home, talk to your contractor about installing an ice and water barrier at potential risk areas on the roof.