What Is Ice & Water Shield?

June 26, 2022

Roofing underlayment is an essential protective layer that is situated between the shingles and the roof deck. In regions with cold weather climates such as the northeast, underlayments usually comprise an Ice & Water Shield, as well as a Felt or Synthetic Fabric. In this article, we will be focusing on the benefits and uses of an Ice & Water Shield.

So, what exactly is an Ice & Water Shield? It is a waterproof, self-adhering membrane that forms a watertight seal between the roof decking and around nail penetrations. It is specifically designed to prevent damage from wind-driven rain, ice dams, and standing water.

Where should you apply Ice & Water Shield? The Ice & Water Shield should be installed in vulnerable areas, including eaves, along walls, valleys, overhangs, skylights, chimneys, vents, and pipe flashings. (Note) We highly recommend applying two rows (72″) on all eaves to maximize performance and prevent damage from ice dams.

There are two main types of Ice & Water Shield: Granulated and Smooth Surface. Granulated Ice & Water Shield is slip-resistant and has a sand-coated surface that aids in better traction and walkability during installation. It is also easier to apply, with a more forgiving adhesive that leads to a lesser chance of folds and wrinkles. Additionally, it is less expensive while providing almost the same level of protection. However, it is more prone to smudging and tearing on hot sunny days, which can lead to a loss of granules and reduced thickness. Its adhesive is not as strong and requires added tape or adhesives to be applied along walls, chimneys, or skylights. Moreover, heavier rolls lead to increased fatigue when applied on steep slope roofs.

On the other hand, Smooth Surface Ice & Water Shield has a much stronger adhesive that creates a better bond wherever it is applied (decking, walls, chimneys, etc.). It offers a greater level of protection, especially for low slope applications. It also has greater tear-resistance and no loss of tar or granules. Furthermore, it is lighter in weight while providing the same or greater thickness, leading to less fatigue and easier maneuverability. It is also easier to re-roof over. However, its stronger adhesive makes it more prone to folds and wrinkles, which leads to more difficult and time-consuming applications. It is slip-resistant but not as good as granulated surfaces, especially once wet/cold. The quality and price vary between each brand, and it is typically more expensive.

What do we recommend? Every roof and underlayment is unique. Whether you have a favorite brand or are looking for the best price, the main factor in your decision should be based on your specific situation. The best thing to do is to consult a professional, whether it is a roofing contractor, a building inspector, or even the manufacturers themselves. To make it easier for you, we have listed our top three choices that we use on a daily basis:

  1. WeatherLock® G Granulated Self-Sealing Ice & Water Barrier
  2. WeatherLock® Flex Self-Sealing Ice & Water Barrier
  3. GRACE ICE & WATER SHIELD® Roofing Underlayment

These are all reliable, quality products that have proven to be effective in protecting roofs from the elements.

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