Here’s a question that builders ask a lot: What is ice and water shielding? And more importantly, when is it necessary? Where Epilay’s synthetic underlayment roofing products are concerned, our Plystik Plus, which is a peel-and-stick underlayment, features Ice Dam Protection. This means that Plystik gives extra protection against harsh winter elements like ice. Additionally, because it’s a peel-and-stick underlayment, it serves as an excellent non-permeable water barrier that shields roof decks from moisture. This underlayment is one that is considered an ice and water shield.
But back to these two questions! Let’s answer them so that you can see how products like Plystik help protect roofs, and so that you know when to use this type of underlayment.
What is Ice and Water Shielding?
In a nutshell, underlayments that offer ice and water shielding are a waterproof membrane designed to protect a roof deck against damage from ice, melting snow and rainwater. These underlayments are always of the peel-and-stick variety. The reason for that is because non-adhesive underlayments installed with fasteners can’t be considered truly waterproof since there is always the chance for some moisture to seep in around fastener punctures.
With a peel-and-stick underlayment, the adhesive is designed to seal around nail punctures to keep water out. The adhesive also means that laps along the sides and edges of the underlayment seal, too, which is another way this underlayment protects against moisture damage.
When to Use Ice and Water Shield
The first thing to do is check with local building codes. In some areas, ice and water shielding may be required. But even if it isn’t required, in most areas, this type of underlayment is often still a wise choice because it serves as an added layer of protection against moisture.
In particular, these underlayments are a good choice in areas that experience severe weather. For instance, in hurricane-prone areas or areas that regularly see high winds, peel-and-stick underlayments help protect the roof deck from rainwater even if shingles are torn off in the wind. When shingles remain intact, the underlayment still protects against threats like wind-driven rain, which can be blown underneath shingles.
They’re also a good idea in northern climates where snow and ice gathers on rooftops. Again, if shingles should be torn off when snow or ice breaks free, the underlayment serves as protection until repairs can be made. Another reason why peel-and-stick is a great choice in snowy areas is because as snow and ice melts and refreezes, this creates an ice dam on the roof. Ice dams form when meltwater refreezes along the roof’s soffit, thus trapping additional moisture as it flows down from upper parts of the roof. Water trapped by ice dams can make its way beneath shingles, and the underlayment is necessary to protect against this seepage.
In fact, ice and water shielding is even more important on low-sloped roofs or in roof valleys, particularly in snowy areas. That’s because on low slopes and in valleys, there is an increased risk of water pooling, which means the underlayment is a necessary defense against moisture damage. Builders will often use ice and water shield around the edges of the roof to protect against ice damming, plus in valleys and around chimneys and other fixtures prone to leakage. To reduce costs, they’ll then use a standard non-adhesive underlayment elsewhere on the roof.
As you can see, ice and water shield isn’t always necessary, though in some places, it is required by code. And in areas prone to high winds and snow, ice and water shield becomes very important for the safety of the roof deck below.
FAQs
No matter the climate, ice and water shield is always a good idea. Think of it as insurance. It's an extra line of defense that protects the structures beneath against potential damage from water infiltration.
Do you really need ice and water shield? ›
It's crucial to have ice and water shield installed on/around certain areas of your roof, like roof valleys, around penetrations, and on roofs that have a 2/12, 3/12, or 4/12 pitch. Because of its importance, every roof needs to have it. There's also a code if you live in an area above the snow line in the US.
What happens if you don't use ice and water shield? ›
If ice dams form on your roof, then you run the risk of serious leaks and water intrusion, which leads to water spots, mold, mildew, and health issues for your family. Not to mention, you'll have to replace parts of your roofing system and repair any interior damage done by the melting snow and ice.
What roof pitch requires ice and water shield? ›
Low-slope roofs, between the minimum of 2:12 and 4:12, are also high risk and should be protected with ice and water protector. Large snow drifts may collect on lower sloped roofs, because they often take the burden of snow from higher pitched roofs above.
What happens if you don't use underlayment on a roof? ›
Without underlayment, this water eventually rots your roof decking leading to leaks, mold/mildew forming, and even structural damage. Can you install a roof without underlayment? Of course, you can. However, a reputable roofing contractor will never recommend skipping underlayment.
How much does it cost to install ice and water shield on roof? ›
According to our research, a reputable ice and water shield should cost around $300 for the material, which is an average cost of $4.72 per square foot. The installation cost is typically more, falling between $265 and $280, but this depends on your area.
Do you need an ice and water shield with synthetic underlayment? ›
Why Do I Need Both? Aside from local regulations requiring an ice and water shield in certain instances, having both layers ensures your roof decking and your home is protected from all types of weather. You want your new roof to perform well and last as long as possible.
How long can you leave ice and water shield uncovered? ›
Extended exposure—Can be left exposed for up to 120 days. Superior adhesion—The self-adhered membrane bonds firmly to the roof deck without heat or special adhesives.
How long does an ice and water shield last? ›
Ice & Water Shield® HT has been formulated and tested to be UV stable for up to 120 days, ensuring the building stays safe and dry during long and unpredictable construction cycles. It delivers the schedule flexibility you need and the waterproofing performance you trust.
How much does it cost to overlap ice and water shield? ›
Valleys and Ridges: Cut the membrane into 4' (1.2 m) to 6' (1.8 m) lengths. In the valley, start at the low point and work upwards, overlapping each sheet at least 6” (15 cm).
The recommended installation of an Ice & water shield is to extend the coverage of the membrane (24”) beyond the “warm wall” of the building (see diagram). Structures with 12” or larger soffit overhangs will require two (2) 3” courses of ice & water shield.
Does drip edge go under ice and water shield? ›
They suggest that the membrane lap down about an inch onto the face of the fascia and then up onto the roof sheathing. This seals the sheathing–fascia joint and blocks the water's pathway into the eaves and soffit. The drip edge is then installed on top of the ice barrier.
Do you really need underlayment? ›
Underlayment is needed if you're going to install vinyl plank flooring over tile, vinyl flooring, and even hardwood. As mentioned, with the plywood floor, there's no need to worry about a moisture barrier; the underlayment should provide cushioning and sound-deadening benefits.
How to tell if a roof has an ice and water shield? ›
You ask your nearby residential roofing contractor to perform a site inspection. Your roofer can safely peek beneath your roofing surface — metal, tile, slate, or shingle — to detect the presence of the all-important ice and water shield.
Do I need tar paper under my shingles? ›
The answer is both yes and no. Technically, no, underlayment isn't 100% necessary underneath asphalt shingles. At least, not in areas unregulated by code! Building codes vary from one region to the next, and most all building codes require felt or synthetic roofing underlayment.
How effective is an ice and water shield? ›
In most cases, if you place the ice and water shield in vulnerable areas — near eaves, valleys, low pitches, and along chimneys, for example — you'll be able to prevent most leaks without spending more money than necessary.
Do you need an ice and water shield under metal roofing? ›
Felt and synthetic underlayment are great options for asphalt roof systems. However, metal roofing needs something different because the expansion and contraction destroys the integrity of the normal types of underlayment. For metal roofing, the underlayment must be high-heat ice and water shield.
Does zip system need ice and water shield? ›
ZIP System tape is not considered a replacement for self-adhering ice and water barriers. Therefore, when self-adhering ice and water barriers are required, they should be installed in addition to ZIP System tape.
Do you need starter shingles with ice and water shield? ›
A starter strip is installed over the underlayment and the ice and water shield along the edges of your roof since these areas are particularly susceptible to water leaks and harsh winds. These shingles have a strip of tar adhesive to prevent your shingles from blowing off in harsh weather conditions.
