TEC Blog

Aug
31
How to Prevent Ice Dams and Leaks on Your Roof With Water Shield Membranes

Few things are as beautiful as the first snowfall. But for many homeowners, the blanket of white signals the return of one of winter's most irritating headaches — ice dams.

Whether your house has a history with ice dams or you're a new homeowner hoping to act preventatively, keep reading to learn why ice dams form, the damage they can cause and how to get rid of them.

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What Are Ice Dams?

Ice dams are long, continuous slabs of ice that form along the edges of your roof. While the dams themselves don't damage your home, they prevent melting water from running off your roof, which can lead to more serious issues.

Often, ice dams indicate a warm attic. Warm air rises and, in most homes, passes through the ceiling into the attic. This warm air heats the wood beams and ultimately the shingles, which melts the snow and ice.

When parts of your roof reach temperatures above 32 degrees, the snow on top of these sections will melt. The water will run down your roof, but most likely, the outside edges aren't warm and have formed an ice dam. The ice dam prevents water from exiting the roof, creating pools of melted snow that seep back underneath the shingles.

Ice dams are common in the valleys of a roof and over soffits. If left untreated, ice dams will grow larger as winter wears on, trapping more and more water behind them.

How Ice Dams Damage Your Home

While ice dams don't directly cause damage to your home, they lead to a dangerous backup of water on your roof. These pools of snowmelt can lead to leakage, which comes with its own host of issues. Here are a few of the damages ice dams can cause indirectly:

  • Wood Rot: As water seeps into the wooden beams and supports of your home, it can lead to rot. This weakens the structural integrity of the house, putting you and your family at risk and leading to expensive repairs.
  • Mold and Mildew: A common effect of ice dams is mold formation within insulation and drywall. Mold and mildew degrade air quality. To eradicate them, you have to replace the affected areas completely.
  • Gutter Damage: Even if a leak doesn't lead to rot and mold, ice dams can significantly damage your gutters. Ice dams often form along or inside gutters, and the weight of the ice can misalign the metal or tear the gutter away from the house.
  • Curled Shingles: The pooled water can lift up roof shingles and cause them to curl, which significantly reduces their effectiveness.
  • Soaked Insulation: Once water seeps into your roof, it can easily soak into attic insulation. Wet insulation is inefficient and can corrode supports, and it can produce mold if left untreated.

Ice dams lead to damage that lasts year-round, not just during winter.

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How to Tell If an Ice Dam Is Forming on Your Roof

It's not always easy to tell if your roof has an ice dam. Keep an eye out for these indicators:

  • Icicles: Not all icicles are a bad sign. Look for many groups of long, thick icicles — these often point to ice dams.
  • Rust Spots: Check the drywall fasteners in your attic for rust spots, which are often indicators of a leak.
  • Peeling Paint: If the paint on your walls and ceilings starts to peel, you most likely have a leak somewhere in your roof.
  • Sagging Drywall: The leaking water from an ice dam will often seep into drywall. Examine visible drywall in your attic. If it looks limp or sagging, it is most likely wet from absorbed runoff.
  • Ceiling Stains: Another sign of an ice dam is water stains on your ceilings, which indicate leaks in your roof. Besides your ceilings, check for stains around the frames of your doors and windows, which are also indicators of an ice dam.

Once you've determined you're dealing with an ice dam, the next step is getting rid of it.

How to Fix Ice Dams

If you have an ice dam but can't detect any leaks or issues, you might not have to take immediate action. Instead, undertake preventative measures in the spring. But if you notice signs of leaks or other damage, you will need to act quickly to protect your roof and your home. Here are three things you should do.

1. Rake off the Snow

One method of handling an ice dam is to rake off the excess snow using a specially designed snow rake. An aluminum scraper attached at a right angle to a long, telescoping rod, a snow rake is the simplest solution to dealing with the effects of heavy snowfall.

If you can pull down the excess snow before it can melt, an ice dam can't form or grow. However, raking off snow can be tedious — you have to rake after every significant snow. Additionally, snow raking is typically limited to single-story homes. A snow rake can't reach much higher than one story, and you should never attempt to rake while standing on a ladder.

2. Install Heat Cables

Heat cables are another way to deal with ice dams. Heat cables are high-resistance wires mounted on the edge of your roof in a zigzag pattern and are most useful in areas where ice dams regularly form. They are plugged into an outdoor outlet and provide a constant source of heat to the coldest parts of your roof, preventing ice from developing.

When you install heat cables, it's crucial to direct meltwater away from the wires. If not rerouted, the runoff will refreeze in the cold gutters and roof edge. Run the heat cable through the downspout of your gutter to keep it from filling with ice.

3. Steam It Off

If you notice signs of leakage and aren't able to rake off excess snow, consider hiring a professional roofing company to steam the snow and ice off your roof. A steamer acts similarly to a pressure washer, except with hot water. The safest way to remove stubborn ice, a steamer melts snow and ice without damaging your roofing and shingles.

How to Prevent Ice Dams

Ice dams are a common irritation in snowy regions. It's possible to reduce or even eliminate them with a little preparation. To prevent ice dams from forming, the most critical step is to keep your roof cold.

But keeping your roof cold is not a simple task — it requires both proper venting and sufficient insulation. Below are three ways to cool down your attic.

1. Seal Attic Bypasses

In the average home, roughly one-third of heat loss occurs through the ceiling into the cold attic. Most of this is due to air leaks, which can come from many different sources — gaps in the drywall or splits and cracks around light fixtures, chimneys, plumbing pipes and access hatches, to name a few.

These air leaks can be difficult and frustrating to plug. The first step is to climb into your attic and access the insulation. Pull back insulation in areas you think may be leaking, and stop up any gaps or openings using caulk, foam or another sealant. As a bonus, if you successfully seal your attic, you will do more than prevent ice dams — you will save on air conditioning and heating bills.

Depending on your roof, your attic may have low angles that are hard to reach, so sealing your attic can take a significant amount of time and energy. Because of the time investment, sealing your attic is best as a cool-weather project — don't attempt it during hot summer months.

2. Examine Insulation Levels

While you are checking your attic for leaks, measure the depth of your insulation. Most building codes require homes to have between 12 and 14 inches of cellulose or fiberglass insulation. As a general rule, if you have less than eight inches of insulation, you should quickly add more.

But not all insulation types have the same benefits — when you are adding new insulation to your attic, fiberglass and blown-in cellulose are generally better choices than hand-placed batts. They fill much more tightly, especially around joists, rafters and other protrusions.

Consider hiring a company to install new or additional insulation. Handing over your home's insulation to experienced professionals is a worthwhile investment and reduces the chance of costly mistakes.

3. Add Vents

The final step in cooling your attic is to add soffit and roof vents. Proper attic ventilation draws cold air inside and expels warm air from the attic, naturally regulating the temperature of your attic.

The minimum size of a vent opening should be about one square foot per every 300 square feet of the attic floor. The calculation can be complicated when half of the vent area is low on the roof and half is high — look for the exact area of the vents, which is typically stamped on the side of the vent.

Try to install an 8"x16" vent on the underside of the soffit, alternating every other rafter. Along the peak of the house, place a continuous ridge vent to maximize airflow.

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Caution: Check Combustion Appliances

As you seal your home and make it more airtight, examine any combustion appliances, such as furnaces, gas, propane or oil-fired water heaters. These machines can backdraft, which will flood the air with waste gases, including dangerous carbon monoxide. Make sure your appliances are drafting correctly before sealing the air leaks in your house.

Ice and Water Shield Membranes

Sometimes, it just isn't possible to keep your roof cold. When you've tried venting and raking, or if you're looking for a solution without such a substantial investment of time and energy, try applying an ice and water shield membrane.

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An ice and water membrane is a type of self-sealing, adhesive underlayment. Installed underneath your shingles, it effectively waterproofs your roof decking, preventing leaks from heavy rains and ice dams.

While many building codes require some type of water or ice membrane, your roof most likely won't have any shield if you live in an older building. If you battle ice dams every winter, it's probably time for a roof-upgrade.

How Do Ice and Water Shield Membranes Work?

Typically, ice and water shields are a peel-and-stick product. When installing a new roof or shingles, roofers will first lay down a layer of membrane directly onto the deck of the roof.

While the exact materials in the shield will vary from company to company, common components include laminated polyethylene and rubberized asphalt adhesive — both powerful waterproofing agents.

Once under the shingles, the shield repels water from soaking through into the attic and walls of your home. While an ice and water membrane won't prevent ice dams from forming, they will keep backed-up water from damaging your house, reducing the danger of winter ice.

When Should You Use Ice and Water Shield Membranes?

If your home has a history of ice dams and winter leaks, ice and water shield membranes are a thorough and effective long-term solution. You won't have to spend hours installing heat cables or raking off snow after every winter storm — with an ice shield, you can enjoy a stress-free winter and increase the longevity of your home.

It's also a good idea to install ice and water membranes if you're already re-roofing your home. Because ice membranes must be applied underneath shingles, adding them can be an expensive project. However, if you already need to repair portions of your roof, slipping in ice shielding is an easy addition and cost-effective insurance against winter ice.

How Much Ice and Water Shield Do You Need?

You don't have to apply a water and ice shield to your entire roof. Instead, focus primarily on the areas most likely to create ice dams, such as valleys and soffits.

A few factors can influence how much shield you need to apply to your home, including:

  • Degree of Slope: Does your roof have a high or low slope? The slope of your roof will determine where ice dams form and how far they extend, which will influence the amount of ice membrane you'll need to apply.
  • Harsh or Mild Climate: How much snow does your area typically receive every winter? If harsh winters are common, your roof will need more ice shield than climates with gentle, occasional snowfalls.
  • Size of Overhangs: Does your roof have narrow or wide overhangs? Wide soffits typically need more shield than narrow overhangs.
  • Junctions and Valleys: Roof valleys form at the intersection of two slopes or angles. Ice dams are much more likely to occur in valleys, so applying an ice or water shield membrane is a smart precaution.
  • Ventilation and Insulation: Is your attic well-ventilated, and does your roof stay cool in the winter? Cold attics generally mean smaller ice dams, which will reduce the amount of ice shield you need.
  • Type of Exposure: What directions does your roof face? Shaded areas or northern exposures will typically need more ice and water membrane than areas that bask in full sun.

Consult with a professional roofing company to determine how much ice and water protectant is right for your roof. A roofing business will also be familiar with local building codes, which may have specific requirements for ice and water membranes.

Where Should You Apply Ice and Water Shield?

As a general rule, apply ice and water shield membranes wherever ice dams are likely to form. This typically includes eaves and valleys, as well as any protrusions such as pipe boots, chimneys, skylights and roof vents.

Basically, the weakest and most leak-vulnerable sections of your roof should be protected with an ice and water membrane to maximize the life of your roof and your home.

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Quality You Can Trust From The Exterior Company

Ice dams can cause frustrating and devastating damage to your home every winter. Don't leave the integrity of your roof up to chance — at The Exterior Company, we are committed to providing the highest possible quality and professionalism, so you can enjoy a safe and beautiful home for years to come.

We specialize in the areas of your house most affected by ice dams — roofing, insulation, gutters, windows and siding, along with other repair and replacement services. Whatever your needs, The Exterior Company has experienced technicians and roofers ready to help.

This winter, don't stress about ice dams and leaky roofs. Call us at 855-766-3264 or contact us to talk with one of our experienced representatives.


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