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How to Install Ice and Water Shield On a Roof

Installing an ice and water shield is not especially complicated, but accuracy is required. Ice and water shield is a membrane added to the decking of a roof to deter water from entering the structure.

Source: gaf.com

Ice and water shield can be used on essentially any roof design, but it is most commonly found on vulnerable areas of a roof. This membrane can be made from any number of materials, but generally speaking, it will always contain some form of rubber. This makes the ice and water shield flexible and water-resistant, which are the primary benefits of the product.

Here’s everything you need to know on how to properly install ice and water shield on your roof. 

Why Is an Ice and Water Shield Needed?

To understand the need for ice and water shield, it is important to envision how rain and snow impact a roof. Some roof designs are steep, while others are flat or nearly flat. This shape greatly affects how rain and snow exit a roof. To illustrate, consider that on a shallow roof pitch (typically 3/12 or less), rain and snow will exit the roof more slowly than on a steeper pitch.

When ice and snow cannot exit the roof quickly, it accumulates near the bottom edge where the gutters are located. In effect, this is pooling water, which is the enemy of a shingle-style roof. Ice and water shield is installed in this vulnerable area, so that slow melting, seeping water cannot penetrate to the roof decking.

Even a tiny perforation such as a nail hole will leak if it is effectively submerged in water. The ice and water shield resists this by sealing the hole around fasteners automatically. Ice and water shield is also commonly used in valleys because that is where the shape of the roof directs the water.

These areas see much more volume than the rest of the roof, making them vulnerable to water infiltration. Ice and water shield adds another layer of protection beyond the underlayment and roofing material to add years of life to the roof. 

What Tools Do I Need to Install Ice and Water Shield?

Interestingly, an ice and water shield typically requires very few tools to install. The tools required will vary by the project of course, but for most jobs, a tape measure, framing square, chalk line, and utility knife will do the trick.

Obviously, the need for safety cannot be overstated, as doing any roof repairs is inherently dangerous.

Therefore, installing ice and water shield should only be attempted by those with experience working on ladders and roofs, as a slight step in the wrong direction can result in injury.

What Materials Do I Need to Install Ice and Water Shield?

Ice and water shield comes ready to use right out of the box. Ice and water shield usually comes in a large roll approximately 50’ to 150’ long, and 2’ to 4’ wide. This will vary from manufacturer to manufacturer, so it is a great idea to do some research and determine the correct size for the application. Typically, more is better as the more product is on the roof, the better it protects.

Is Installing Ice and Water Shield Difficult?

Not especially, but accuracy is very important to a good-looking job. Professionals will always use a crew of at least two technicians to install ice and water shield, but if the project is large enough, more help may be needed. This is because the material roll is not only heavy but quite awkward to handle.

This can cause a dangerous scenario if a technician loses control of the roll, as it not only endangers the installers but anyone on the ground as well. Best practices require a combination of help, focus, and patience to do a safe and effective job.

Can I Install Ice and Water Shield By Myself?

Installing ice and water shield solo is not generally recommended. However, ice and water shield can also be used as spot repair material. For example, if a roof were to take an impact strike from a falling limb, just the area around the damage would require repair.

Many professionals will not only remove and replace the damaged roofing but will also patch the area first using ice and a water shield. This greatly adds to the protection of the repair and gives the installer more peace of mind. In these situations, a single installer is often used, as the entire roll will not be needed. Working with smaller sections is easier and will often be safer.

How To Install Ice and Water Shield (Step by Step)

  • Step 1. Inspect the Roof Decking

The first step of installing ice and water shield is to prepare the roof decking. This is done by visually inspecting the entire area to be covered and removing any debris.

Oddly, one of the biggest concerns before installing ice and water shield is dust. Roofing projects tend to generate dust and debris, which will stick to the self-adhesive backing on the material.

Therefore it is critical that the roof deck be broom clean before removing the protective backing on the material. Also important is to lay out the project visually to determine where, if any seams will be required. It is not as important to stagger joints when using ice and water shield as it would be with other materials, such as shingles or siding.

However, it is still a good practice, as it will prevent visual undulations that can occur when joints overlap each other.

  • Step 2. Measure, Mark, and Cut the Materials

The next step involves calculating the amount of material needed. To illustrate, let’s assume the product we are using is 2’ wide and 50’ long, which is typical. We want the ice and water shield to completely cover the roof decking, which is usually OSB or plywood, but it can be 1” x 6” boards. Next, we measure out the length we need, so in this case, let’s say the house is 48’ long. For simplicity, let’s also assume the home is a simple rancher with a gable roof. Since a 48’ longhouse will typically have an overhang of 12” on both ends, we will need a 50’ long section. On the ground, we then use the square and using a utility knife or hook blade, easily cut the material. 

Pro Tip. Do not remove the protective backing on the material until just before it makes contact with the roof. If the sticky side of the material contacts any surface except the roof deck (including itself), it must be discarded and replaced as it is nearly impossible to detach.

  • Step 3. Install Ice and Water Shield On the Roof’s Edge

At this stage, we have the material on the roof, but we need a reference line to keep the material straight. Professionals will do this with a chalk line. First, we measure from the left edge of the roof straight up and mark exactly 24”. We then do the same on the right side.

Using the chalk line, we then strike a mark all the way across the roof. Next, we find the middle of the roof, which in this case will be exactly 25’ from either side and make another mark two or three feet long straight up the roof. This is our starting point.

Using help, we roll out the material above the line and locate the middle of the roll, which is again 25’, and make a mark across the ice and water shield bottom to top. We now have intersecting lines we can reference to keep the material straight and square.

Next, we line up the vertical marks on the material and roof deck and carefully roll the material in towards the lines from either end. The next step is to flip the material over, so that the protective backing is facing up. Starting from the center, we then remove about 12” of backing on either side on the centerline, for a total of 24”.

Next, the roll is lifted above the lines on the roof deck and very slowly and deliberately lowered onto the deck, making sure the reference lines are followed. We then carefully press the material onto the roof, all the while making sure the material follows the left to right line on the decking. This will ensure that no puckers or gaps can form under the material and cause a hump in the roofing.

We then follow the same process, removing only enough protective backing as needed until the entire section is installed. If needed, an additional course can be added above the first using the same techniques, and vertically overlapping the course by at least 2”.

  • Step 4. Install Ice and Water Shield In the Valleys

Lastly, if the structure has valleys, it is a good idea to install ice and water shield there as well. The installation procedure will be the same, except in this situation, we will install the material on one side of the valley at a time to prevent trapping air under the material.

Installing Ice and Water Shield Is Money Well Spent

Although not all local building codes require ice and water shield, it is a very smart idea. As described here, the material really has no downsides and plenty of benefits. Ice and water shield is relatively inexpensive to purchase and install and works hard to protect one of the most critical parts of a home from expensive repairs.

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