Homeowners living in snowy, cold-winter climates will know the pain of experiencing ice dams. An ice dam is a mass of ice that forms along the lower edge of your roof. It can damage both your roof and the inside of your home. It may even damage your rain gutters and downspouts. So, what should you do about ice dam prevention? That’s exactly what we’ll learn from this article!

Ice dams and icicles can weigh hundreds of pounds — sometimes even tearing off your gutters, loosening your roof shingles, and causing water to back up into your living space. If ignored, the water can flow down and ruin your house’s ceiling and interior as well as exterior wall surfaces — causing serious damage to your roof, paintwork, insulation, and interior drywall.

This article lists useful ice dam prevention tips. But, before that, let’s understand the causes of ice dams and icicles. 

Read more: Want an Expert’s Advice on Roof Leak Repair?

What causes ice dams?

ice dam causes

An ice dam forms at the edge of a roof — preventing the melting snow or water from draining off the roof. As a result, the melted water may begin to leak into your home, causing severe damage.

When the snow melts, it runs down your roof and refreezes near its edges. The reason is the temperature difference between parts of your roof. Some portions become warm enough to melt the snow — to above 32 degrees F — while the roof edge remains below freezing. 

Why is there a temperature difference?

Mostly, ice dams are the result of warm attic space. Heat escapes through ceilings into the attic and warms the wood and roof shingles above it. As a result, the snow melts over the warmed part of the roof. When the meltwater runs down the roof, it refreezes — creating a rim of ice that over a period of time traps water behind it.

Contrary to popular belief, rain gutters do not cause ice dams. They do help to concentrate the ice and water at your roof’s edge though. As your gutters fill with ice, they bend and rip — bringing down the fascia, fasteners, and downspouts with it.

The resulting damage can easily cost you thousands of dollars in repairs and replacements, especially if the snow remains on the affected roof for a long time.

Although a metal roof is a better choice when it comes to shedding snow better, it doesn’t prevent snow from freezing on the unheated overhangs. To put it simply, ice dams are not a roof-material problem. They are more to do with heat loss and insulation issues.

The best way to prevent ice dams

preventing ice dams on roof

Ice dam removal is a pain. It’s best if you can prevent them from forming in the first place. The principle behind preventing ice dams is keeping your attic and roof cold. Let’s see some methods through which we can achieve this. 

1. Close up the attic bypasses

Houses experience a lot of heat loss through the ceiling into the attic — almost about one-third. Most of that heat loss is due to air leaks caused by gaps in drywall, cracks around light fixtures, plumbing pipes, unblocked walls, or chimneys.

You need to stop as much air leakage as you can to mitigate ice dams. You could begin by plugging the leaks using foam, caulk, and other methods. This also helps you to save energy and reduces your heating and cooling bills. 

Read more: Plumbing Tips to Help You Prepare For Winter

2. Ventilate the eaves and ridges through roof vents and soffit vents

Ridge vents and soffit vents help to circulate cold air under the entire roof. Just make sure that they have the same size openings — with a minimum ventilation area of 1 square foot opening for every 300 square feet of attic floor. To maintain a clear path for the airflow from the soffit vents, you can place baffles at the eaves.

A good attic ventilation system will draw in cold outdoor air and flush out the warmer attic air. This will successfully cool the attic as well as the roof. 

3. Upgrade your attic insulation

You must examine the depth of your attic insulation and, if required, upgrade it to an R-value of about R-40. Keep in mind that blown-in cellulose and fiberglass are better than hand-placed batts as they leave fewer gaps around the rafters and joists by filling more tightly. 

In most states, building codes require 12-inch to 14-inch fiberglass or cellulose. To find out exactly how much attic insulation your house needs, you must check with your local building department.

Read more: A Brief Introduction to Home Insulation

4. Cap the attic hatch and ducts

An unsealed attic hatch allows heat to escape. Make sure you cover any opening (even a whole-house fan opening) with weather-stripped caps made from foil-faced foam board. Hold them together with aluminum tape.

Use fiber-reinforced mastic on the joints of your HVAC ducts as well as exhaust ducts. Make sure to cover them with R-5 or R-6 foil-faced fiberglass.

5. Lead all exhaust to the outside

You must ensure that all the ducts (connected to the kitchen, bathroom, and dryer vents) lead to the outside. They should open outdoors through either the roof or walls — never through the soffit.

6. Install sealed can lights

Replace your old recessed lights with sealed IC light fixtures. The old style of lights give off a lot of heat and are a fire hazard. Moreover, they cannot be insulated properly. Replace them at the earliest with newer can lights that can be covered with insulation.

7. Get flashing around your chimney

Bridging the gap between your chimney and house framing will help in maintaining your roof’s temperature. Use L-shaped steel flashing with unbroken beads of a fire-stop sealant. Do not use canned spray foam or else your insulation won’t be fire safe.

What to do if you already have ice dams?

To stop any kind of leakage from an ice dam, the best way is to remove snow from the roof. If you’re unable to use a snow rake yourself, hire a roofing company to steam it off. 

A steamer is like a pressure washer, but with hot water. It melts the ice away without damaging the roofing and aids in ice dam removal. Do not chip the ice off with a hatchet or an ice pick. It can break or puncture your roof shingles.

Read more: Roof Leak Detection: Complete Lowdown by an Expert

Last thoughts

For long term ice dam prevention, you need to keep the entire roof the same temperature as the eaves. The best ways of doing that are by increasing ventilation, adding insulation, and sealing off every possible air leak.

The idea is to not let the underside of the roof warm up. If you take care of these points, you’ll be able to enjoy a winter free of ice dams and icicles.

Useful Tips for Long Term Ice Dam Prevention was last modified: October 25th, 2021 by Ramona Sinha
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