Q&A / 

Ice And Water Shield

DEAR TIM: Lately I’ve seen roofers install a strange product that looks like traditional felt paper, but it’s not. It has a peel-away backing paper, and this material sticks to the wood sheathing. What is it? Why would you use this on a roof? Is it something that can be added to an existing roof in case I’m adding another layer of shingles? Connie G. Columbus, OH

DEAR CONNIE: Without being there, I’m willing to wager that you saw ice and water shield being installed. It’s an amazing roofing product that was introduced in the 1980’s and has quickly become the gold standard for creating leak-free roofs in all climates.

This entire roof has been covered with an ice and water shield. It’s going to be leak-free for many years. PHOTO CREDIT:  Tim Carter

This entire roof has been covered with an ice and water shield. It’s going to be leak-free for many years. PHOTO CREDIT: Tim Carter

Roofing ice and water shield may look like traditional felt paper, but it’s vastly different in performance. Traditional felt paper does a very good job at stopping most leaks where water gets under shingles, tiles, metal or slate. It does this by not allowing the water to come in contact with the wood beneath the actual roofing material.

But felt paper has problems where it overlaps the sheet below and where the nails penetrate the felt. If water backs up under the roof as happens with ice damming, water can flow up and under the lap joints of felt paper.

Where the nails used to attach the roofing materials penetrate felt paper, the actual hole created by the nail is not sealed where it passes through the felt paper. Water can get under the head of the nail and seep down the shaft of the nail where it passes through the felt paper. When this happens, you get leaks into your home.

The roofer still needs to install a small strip of the ice and water shield at the lower edge of the roof. He'll do that after removing the 2x4 cleat that prevented him from falling to the ground. PHOTO BY: Tim Carter

The roofer still needs to install a small strip of the ice and water shield at the lower edge of the roof. He'll do that after removing the 2x4 cleat that prevented him from falling to the ground. PHOTO BY: Tim Carter

The ice and water shield roofing material is made with a rubberized asphalt mixture that solves these problems. Because the product has a very sticky backing, it not only adheres well to the wood roofing sheathing, but it also sticks well to the layer below when you overlap the pieces.

When nails penetrate the ice and water shield on the roof, the rubberized nature of the material creates a gasket effect on the shaft of the nail. Leaks simply don’t happen.

This newer roofing material, that’s hidden by the finished roofing materials, is perfect for many houses. Not only does ice and water shield installation stop leaks caused by ice dams, but it also stops leaks created by fierce wind-driven rain. If you live in an area that’s frequented by hurricanes or severe thunderstorms that can drive rain sideways, then you need this material. These storms can easily push water under many finished roofing materials.

You can cover the entire roof with the ice and water shield, but in many instances it’s applied where leaks frequently happen. For ice damming situations, you may want the product to extend up from the edge of the roof at least 3 feet. If the roof has a low slope, you absolutely want to extend the barrier product up the roof quite a distance. I would also apply it in any valleys you may have where two roof planes intersect.

This pliable material is perfect to use around skylights, chimneys, plumbing vents, ventilation caps, or anything that penetrates up through a roof. The roofer laps the material up onto the object and cuts it at corners or curves in a special way to create a leak-proof barrier. Traditional roof flashings then cover this sub-flashing made from the shield product.

If you’re re-roofing, you can use this product. But you can’t apply it on top of the old shingles. You must apply this product as indicated by the manufacturer. Typically you’ll discover that you must apply the material directly to the wood roof sheathing that’s under the shingles and any old felt paper.

Working with ice and water shield can be challenging, especially in warm or hot weather. In these conditions, the back of the material is very sticky. If you start to unroll it and you’re not aligned correctly, you can install it crooked. If you try to straighten it out, you’ll almost always get a wrinkle.

Be prepared for a slight learning curve when using the material for the first time. If you’re not astute at how it should be installed, by all means read all the tips from the manufacturer and watch any videos they may have about how to best handle the material.

If you’re working on a steep roof, you need to be very careful. Wear all required fall-protection equipment and watch out when stepping on the material if it’s damp, frosty or cold. It can be very slippery. Falling from a roof can really ruin your day. I know, as it’s happened to me on more than one occasion.

Column 861

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5 Responses to Ice And Water Shield

  1. Looking to get a low slope sunroom roof re-done. There are 2 skylights. The skylights are leaking and will be replaced. The roof is leaking above the rear windows; we are told the water from the skylight leak is traveling on the downward slope and emerging above these widows. We have been advised to go with a rubber roof. Can 'ice and water shield' be used with a rubber membrane system? Is a rubber roof the best way to go?
    How about an ice and water shield and a different roof system ( tar and paper?). Please advise. We are in Canada ( cold winters). Your input much appreciated. I am very concerned to do the best thing and solve this leak problem.

  2. I need to know if you need to remove ice and dam when reroofing ? Does it need to to be recovered, or can it be just reused?

  3. Ice and water shield is crap...if you ever have to replace your roof, like after a hail storm. You can't remove the shield, so you have to replace all the wood as well. Insurance won't cover the cost, so the home owner, like me, has to PAY TO HAVE YOUR WHOLE ROOF REPLACED. This article is crap!! Don't buy it!!

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