Ice and water shield is a critical component of modern roofing systems, designed to prevent water infiltration from ice dams, wind-driven rain, and other water-related issues. When installed correctly, this self-adhering membrane creates a durable and flexible water barrier in high-risk areas of the roof. This article provides a detailed overview of installation best practices, key locations for placement, and essential tools and techniques for ensuring a secure and effective application.
Overview of Ice and Water Shield
An ice and water shield is typically made of a rubberized polymer-modified bitumen material that self-adheres to the roof deck. It acts as a secondary water barrier beneath roofing materials such as asphalt shingles, metal panels, tiles, and wood shakes. The material is designed to adhere firmly to the roof surface and expand or contract with temperature changes, maintaining its protective qualities over time.
This type of underlayment is especially important in areas prone to heavy snowfall, ice dams, or frequent storms. It is often used in conjunction with traditional roofing underlayments and flashing to provide an added layer of protection against leaks.
Preparing for Installation
Inspecting the Roof Deck
Before beginning the installation process, it is essential to inspect the roof decking. The surface must be clean, dry, and free of debris. Even small amounts of dust or moisture can interfere with the membrane’s adhesive backing, reducing its effectiveness. If the surface is not properly prepared, the membrane may not adhere correctly, leading to weak spots that could allow water to penetrate.
It is also important to ensure that the roof structure is stable and free of any damage or rot. Any issues with the decking should be addressed before proceeding with the installation of the ice and water shield.
Measuring and Planning the Layout
Careful measurement and planning are essential to minimize seams and overlaps, which can create weak points in the water barrier. The shield should be applied in areas where water is most likely to accumulate, such as eaves, rakes, valleys, and around roof penetrations like chimneys, skylights, and plumbing vents.
For eaves, it is recommended to install the shield at least 24 to 36 inches up from the edge, depending on the climate. In colder regions, a 36-inch coverage is often necessary to protect against ice dams. For valleys, the shield should be installed along the full length of the valley and extend at least 6 inches onto adjacent roof planes to ensure proper overlap.
Considering Weather Conditions
The installation should be performed during moderate temperatures. Extremely cold weather can make the material stiff and difficult to work with, while hot conditions can make it too soft and sticky. A mild day is ideal for installation, as it allows the material to adhere properly without becoming too rigid or too pliable.
Manufacturers often specify acceptable temperature ranges for installation, and these should be followed to ensure proper adhesion and long-term performance.
Tools and Materials Needed
The following tools and materials are typically required for the installation of an ice and water shield:
- Tape measure: For accurate measurements and layout.
- Framing square: To ensure precise alignment of the membrane.
- Chalk line: For marking the layout on the roof surface.
- Utility knife with sharp blades: For cutting the membrane to size.
- Broom: To clean debris from the roof surface.
- Sturdy ladder: For safe access to the roof.
- Nonslip shoes: To improve traction and reduce the risk of slipping.
- Fall protection gear: For safety when working at heights.
Step-by-Step Installation Process
Measuring and Marking the Roof
Using a tape measure and chalk line, mark the areas where the ice and water shield will be installed. For eaves, measure at least 24 inches past the interior wall line. In valleys, extend the coverage at least 18 inches on each side to ensure full protection.
Careful planning is necessary to minimize seams and overlaps. Where possible, the shield should be installed in continuous strips to reduce the number of weak points in the water barrier.
Installing the Membrane
The membrane is typically installed in rolls ranging from 2 to 4 feet wide and 50 to 150 feet long. To begin, unroll the membrane along the marked lines and press it firmly onto the roof deck. A roller can be used to apply even pressure and ensure proper adhesion.
If multiple courses of membrane are required, the higher course should be overlapped over the lower by at least 6 inches. In valleys, the shield should be installed on one side of the valley at a time to prevent air from becoming trapped underneath.
Handling Valleys and Penetrations
Valleys are high-risk areas for water infiltration and should be carefully sealed with the ice and water shield. The membrane should be run the full length of the valley and overlapped by at least 6 inches on each side. In some cases, a double layer of membrane may be used in heavy-rain regions to provide additional protection.
Around roof penetrations such as chimneys, skylights, and plumbing vents, the membrane should be cut to fit and installed below the flashing. Patches should extend at least 6 to 12 inches beyond the penetration to allow for proper shingle laps and flashing integration.
Ensuring Proper Adhesion
Proper adhesion is critical to the effectiveness of the ice and water shield. The membrane should be pressed firmly into place and any wrinkles or misalignments should be corrected before finalizing the installation. A roller can be used to apply even pressure and ensure that the membrane adheres properly to the roof surface.
Avoid common mistakes such as not applying the membrane firmly, improperly preparing the surface, or misaligning the membrane. These errors can lead to gaps or weak points in the water barrier, increasing the risk of leaks.
Key Installation Locations
Eaves and Rakes
The most common recommendation is to apply ice and water shield across the eaves and rakes. For colder climates, building codes and manufacturers suggest installing a 36-inch-wide strip from the eave up onto the roof deck to protect against ice dams. On rakes, the membrane should be extended over the rake edges to seal the shingle edge and roof deck.
Ridge, Hips, and High Roof Edges
While not always mandatory, placing ice and water shield in valleys adjacent to hips or near ridgelines where wind-driven rain can blow under shingles adds an extra layer of protection. Targeted flashing at hips and exposed ridges where leaks have occurred historically is also recommended.
Valleys
Valleys channel a significant amount of water during storms and are high-risk locations for leaks. The best practice is to run the ice and water shield along the full length of the valley, ideally as a continuous strip centered in the valley at least 18 to 24 inches wide. In some cases, wider or double-layer applications may be used in heavy-rain regions.
Flashings and Penetrations
Ice and water shield should also be installed around all roof penetrations, including chimneys, skylights, plumbing vents, and roof-mounted equipment. The membrane should be cut to fit and installed below the flashing, with patches extending at least 6 to 12 inches beyond the penetration to allow for proper shingle laps and flashing integration.
Code Requirements and Manufacturer Recommendations
Building codes and local ordinances vary, and many require ice and water shield in specific locations. For example, the International Residential Code (IRC) often requires a self-adhering polymer-modified bitumen underlayment in eave areas in certain climate zones.
Manufacturers provide detailed installation instructions, including acceptable installation zones, adhesive temperature ranges, and overlap details. These instructions should be followed carefully to maintain product warranty and ensure proper performance.
Conclusion
Ice and water shield is a critical component of modern roofing systems, providing an essential layer of protection against water infiltration. When installed correctly, it can significantly reduce the risk of leaks and extend the life of the roof. Proper installation requires careful planning, attention to detail, and adherence to manufacturer recommendations and local building codes.
By following the guidelines outlined in this article, homeowners and roofing professionals can ensure that their roofing systems are well-protected against the elements, offering long-term durability and performance.