An Overview of Ice and Water Barriers for Roofs

Water damage is one of the biggest threats to most roofs. Ice and water barriers go a long way in preventing the threat. Below is an overview of ice and water barriers.


Different manufacturers produce ice and water barriers and give them different names. The barriers also have different generic names in the roofing industry. For example, some people call them ice and water shields or ice and water protectors.

Ice and water shields have roughly the same materials despite their different names. The main material is asphalt (polymer-modified bitumen). Asphalt is the material of choice since it does not absorb water easily and is relatively cheap.

The ice and water barrier is available as a sheet with a release film. The roofing contractor peals the release film during the application, exposing a sticky surface that sticks to the roof deck. You do not need to apply a seal to the barrier. The material has a self-sealing property that allows it to close around nails and other roof projections and form a watertight barrier.


The roofing contractor installs the ice and water barrier directly onto the roof. If your roof requires multiple sheets of barriers, the contractor installs the bottom layer first and overlaps the top layer. That design prevents water flowing down the roof from penetrating under the bottom shingle layer.


Any roof with a high risk of water damage would benefit from an ice and water barrier. Below are some factors that determine whether your roof needs ice and water barrier.


Drainage is a common problem for flat or low slope roofs. The problem is common since water usually flows down the roof due to gravity, ineffective on low-pitched roofs. Thus, you should cover as much of your flat roof with the barrier. Cover even the entire roof if possible.


The precipitation your neighborhood receives determines your house’s risk of water damage. Cover the entire roof with the barrier if your area receives considerable rainfall every season.


Local building codes determine which roofs need ice and water barriers. Many places require the barrier for roofs with high risks of water damage. Most jurisdictions consider climate and roof slope to determine roofs that need the barrier.


The ice and water barrier doesn’t have to cover the whole roof. Just install it on parts of the roof with high risks of water damage. Here are examples of such areas.


Ice dams form when the snow melts on the upper, warmer surfaces of the roof and freezes on the colder, lower surfaces. The dam prevents further water flow from the roof. The dammed water can penetrate the shingles and pass through the roof. Strong winds can also lift the edges of the shingles and drive rainwater under them.


Thus, you should install the ice and water barrier if your winter temperatures fall low enough to form ice dams. In such a case, install the barrier along the house’s eaves.


Joints are weak points of the roof as far as water damage is concerned. Examples are joints between the roof surface and penetrations, such as chimneys and vents. Roofing contractors use flashing materials on joints to minimize such risks. An ice and water barrier under the flashing improves water protection even further.


Any part of the roof where water accumulates or handles large volumes of water risks damage. Since roof valleys collect and drain large volumes of water, they need the ice and water barrier to minimize the risk of water damage.


A professional roofing contractor will ensure your roof has the best design for weather-damage prevention and code compliance. iHome Designs is a licensed and experienced roofing company. Contact us for all your roofing needs and benefit from our professional skills and experience.