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Is Ice And Water Shield Necessary?

If You're Wondering Whether Ice And Water Shield Is Necessary Or Not, Then Read On For All The Details.


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Is Ice And Water Shield Right For My Roof?

A lot goes into house construction. Among the decisions to be made include whether or not to have an ice and water shield as part of roof installation.

Is this a necessary must-have in construction, or can you bypass it? To answer this question, it’s best to understand what an ice and water shield is and its role in roofing.

What Is an Ice and Water Shield?

Most homes in the US bear the popular gable-shaped roof. This type of roof has slopes and inclined angles designed to help counter elements of nature. These roofs can easily shed off water and ice instead of them lingering on the roof’s surface.
However, this does not eliminate all water risks from the roof.
An ice and water shield, or protector, is a waterproof roof underlayment. This underlayment is designed to protect vulnerable parts of a roof from water damage. These roof protectors are made from polymer-modified Bitumen. In snowy areas, you can get ice and snow shields, largely for the same purpose.
Most of these waterproof membranes are of the peel and stick variety. These waterproof membranes have an adhesive back surface covered by a release film. This film is peeled off during installation so that the sticky membrane adheres to the roof deck. Roofing feels differently.
When properly applied, water shields will also form watertight side laps and end laps.

If shingles are applied, the modified bitumen still creates a watertight seal around their nail penetrations as well.

These peel and stick options are more convenient and effective because they do not have fasteners. Roof protectors that are applied using fasteners cannot be considered completely waterproof. There is always the chance of water seeping through the punctures created to hold the fasteners in place and eventually causing a roof leak that needs repaired.

Additionally, these protectors have slip-resistant qualities offering better traction.
Typically other protective devices tend to slip off roofs when exposed to ice and water. Covering an entire roof with ice and water shields makes roofs resistant to strong wind conditions that might blow shingles off the roof.
This is useful on two fronts. The first is that if you still suffer damage, the impact will be greatly minimized by the ice and water shield.
The second is that making repairs after damages will be much more convenient and possibly even simpler. This is because the shield will still offer some protection and prevent water damage even after shingles are blown off.
All in all, homeowners still have to be mindful of having proper attic ventilation. Because a modified bitumen’s surface is continuous, these membranes can yield a vapor barrier. Therefore, proper attic ventilation is fundamental if you opt to cover your entire roof with an ice and water shield.

Where Should Ice and Water Protectors Be Applied?

Where are the ideal locations to place your ice and water shields for optimal protection?

Here are some areas to do the installation:

  • Most roofing experts will place a shield on rake edges, eaves and valleys, and overhangs. These tend to be the most vulnerable areas when it comes to wind-driven rain and ice dams. In some jurisdictions, these may be building code requirements. 
  • Chimneys and vent stacks should have ice and water shields underneath their flashing. This is because the flashing and or shingles in these areas rarely overlap completely. These leaves spaces that can let in water. 
  • Any roof features that penetrate the roof deck, including skylights and dormers 
  • Roofs with low inclines of between the minimum of 2:12 and 4:12 carry a higher risk of damage. Large snowdrifts can accumulate on lower sloped roofs as they tend to take the burden of snow from roofs pitched higher than them. Ice dams also have the potential of climbing higher up low sloped roofs. 
  • If you are building a house in an area with severe wind-driven rain or ice dams, it’s typically recommended or required to have ice and water shield over the entire surface of your roof. Otherwise your roof could be susceptible to damage, increasing the likelihood of your roof leaking during heavy rain.

Are Ice And Water Shields Necessary?

Many people building homes want to have the house of their dreams while keeping costs low. It might be tempting to leave out certain features in order to keep building costs under control.

Ice and water shields are often foregone, largely because their importance is not really understood. After all, shingles and other roofing materials do direct water away from a roof, right? Well, yes and no. Shingles and most other roofing materials are designed to handle water that falls on the roof vertically.

However, water will fall on the roof horizontally in some cases, for example, when there are strong winds. This can see water slip inside through the tiny spaces between shingles.
Similarly, snow can degrade shingles, allowing water in. If this does happen, having an ice and water shield underneath provides an additional layer of protection.
This begs the question? Are ice and water shields necessary?
The best way to answer this question is to understand what could happen if you forego shield installation.

What Happens When Water Gets Under Your Roof?

While water on your roof doesn’t hurt much, water seeping under your roof can, over time, lead to severe damage which can turn into quite a bit of money. If you are thinking about not getting ice and water shield, maybe look into the costs to install a new roof and it will likely seem like a much better idea.

Here are some possible outcomes:


Corrosion – Most house foundations are built with concrete or wooden beams. Both these materials are vulnerable to water damage. Flowing water and moisture can corrode these materials, which then interferes with your home’s structural integrity. In addition, water can cause wood to rot and cause dark, unsightly stains on wooden surfaces.


Increase Moisture In The Roof Decking – Water does not always have to get inside your roof’s interiors to cause damage. At times, moisture can be trapped inside the roof, causing sweating. There are many reasons why this happens, including insulation being too thick or having inadequate ice and water protector. A clear sign of water getting in under your roof is rotting, mold, and mildew. Always call a roofing expert whenever you spot these.


Additional Weight – Snow will usually fall on the top of the roof and melt off. However, during colder seasons, ice takes much longer to melt. This means it accumulates on the roof’s surface, adding weight to it. While a bit of snow is no cause for alarm, a lot of snow can become weighty and can begin to damage your roof’s support beams. An ice and water shield is necessary if you live in a very cold area and have a low-slope roof.

Types Of Ice and Water Shields

There are three types of ice and water shields. These are:


  • Granular/sanded
  • High heat
  • Smooth surface


Granular shields are the thinnest of the three types and are typically applied on valleys of roofs. The smooth surface shields are used on low slopes, while high heat shields are mostly used on metal roofs. These are cotton-like fibers and do not get stuck on metal surfaces as they contract and expand.

Still Have Questions?

If you are building a new home, doing major repairs, or recently suffered roof damage, you might want to consider having an ice and water shield at least in the most vulnerable areas, but feel free to reach out to us and go over options that will best suit your property.