Ice & Water Shield

Ice & Water ShieldIce and Water Shield is an underlayment material that is installed under shingles instead of felt. Depending on your region of the country, the Ice and Water Shield requirements might include the valleys, ridges, eaves, gables, pitch transitions, and penetrations. Typically, in the southeast part of the US, Ice and Water Shield is only required to be installed in valleys and at penetrations. The purpose of Ice and Water Shield is to create a more effective underlayment barrier where snow and water loads on roofs will be higher.

Codes requirements for Ice and Water Shield per the Internationals Residential Code:

IRC Ice & Water Code

When considering Ice and Water Shield for your roof, there are a few things to keep in mind:

  1. Ice and Water Shield versus underlayment/felt.
  2. The functions Ice and Water Shield performs.
  3. Ice and Water Shield as it relates to what insurance will cover.


Ice and Water Shield Vs. Underlayment/Felt:

RoofersIce and Water Shield and underlayment/felt serve similar but different purposes. In short, Ice and Water Shield like underlayment protects the decking from water penetration. However, it does it in the areas of the roof that are prone to excess water or ice coverage. Essentially, Ice and Water Shield is underlayment on steroids.

Ice and Water Shield is typically found in valleys and any low slope areas as these areas will collect water the most. Keep in mind that depending on the area you live in there might be certain codes mandating where Ice and Water Shield must go (same as with underlayment). While underlayment is able to be applied across an entire roof, Ice and Water Shield is thick and does not permit the house to breath the same way as underlayment, so it is not recommended to be used in any areas except those that have excesses of water.

One of the other differences between Ice and Water Shield and underlayment is the way it’s made. Ice and Water Shield comes in both the most common granulated version, and non-granulated versions, with the latter being best for metal roofs because it doesn’t scratch the metal.

Here we see an example of granulated Ice and Water Shield on the left and smooth on the right.

Granulated Ice and Water Shield
Non-Granulated Ice and Water Shield

The Functions Ice and Water Shield Performs: 

Ice & Water Shield Around Nails

Ice Dam Protection MapSo other than being a thick, durable product, how does ice and water shield perform its very important function? Ice and Water Shield actually seals around the nails that are put through it, making the holes extremely watertight. It’s also a peel and stick product, which helps eliminate the need for more nails than necessary in your roof. Keep in mind exactly what job function Ice and Water Shield performs varies slightly depending on the region it is used in. In the northern area of the United States Ice and Water Shield is beneficial to preventing what is called “ice damming”. “Ice damming” is when heat from your home melts snow on your roof, causing water to run down the roof towards the cooler edges of the soffits and eaves where it refreezes. When this happens, water can be forced up under the shingles and into the home. Ice and Water Shield is designed to prevent this in colder climates. In the southern area of the United States Ice and Water Shield battles the excess rain that can overtake certain areas.

Ice and Water Shield as it relates to what insurance will cover:

Insurance companies oftentimes do not put high priority on the use of Ice and Water Shield because it is a way for them to cut corners on payouts. Instead of paying for the cost of Ice and Water Shield they will oftentimes push the cost of purchasing Ice and Water Shield onto the consumer. Another practice they might use is to put the cost of this product on the contractor if they don’t put it on the consumer. If you do find Ice and Water Shield paid for by an insurance company it oftentimes has stipulations, such as stating that they will only pay for it if it was present on the old roof. Supplement your insurance company for Ice and Water Shield, they owe you for it! The International Residential Code defines Ice and Water Shield as being necessary in areas that have a history of ice forming and causing a backup of water. It specifies that “…two layers of underlayment cemented together of of a self-adhering polymer modified bitumen sheet, shall be used in lieu of normal underlayment…”. For further information on barrier importance please see the GAF technical bulletin below:

GAF Full-Deck Coverage With Leak Barrier

In short, there are a few things we can keep in mind when considering Ice and Water Shield:

Ice and Water Shield is similar to underlayment/felt but is used in valleys where excess water flows: True

Ice and Water Shield should not be used across an entire roof like underlayment is because it prevents a roof from being able to breath: True

Ice and Water Shield only comes in one texture:
False – It can be made granulated and un-granulated

Ice and Water Shield seals in around nails making a watertight seal stronger than underlayment: True

Ice and Water Shield is used for the same purpose nationally:
False – In the northern US it prevents “ice damming” while in the southern US it keeps rain out from under shingles.

Insurance companies consider Ice and Water Shield a necessity:
False – They will often only deem it a necessary cost to put back on a roof if it was present on the old roof.

Insurance companies often pass off the cost of Ice and Water Shield to the consumer or contractor: True

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