About Ice Dams

Preventing Ice Dams

The key to preventing ice dams is to simply keep your roof cold.

To keep your roof cold follow these steps:

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1. Fix the ventilation. A cold roof has an even blanket of snow while a warm roof will have hot spots where the snow is melting. Seek out a professional who is trained and skilled in antic ventilation. This is beyond most shingle sales people.  

2. Attic soffit vents allow cool air to enter and ridge vents or can vents will allow air to escape. You need a minimum of 1 square foot of intake and 1 square foot of exhaust per 150 square feet of attic. Not all ridge vents are created equal. A good high performance ridge vent is Hi-Flow.
    

Assess Your Insulation

1. Measure the moisture content in your insulation with a moisture meter. Moist insulation is ineffective and is letting the heat escape. Proper ventilation will dry the insulation so it becomes effective in keeping the heat in.

2. Add insulation to increase your insulating ability. Do not put new insulation over wet insulation.

 

Close up Bypasses

Over a third of the heat escaping your home is through cracks around ceiling fixtures, pipes, electrical wires, chimneys and drywall gaps. Seal these leaks by pulling back the insulation and filling the holes with foam. By stopping the warm air from entering the attic you will also save energy dollars.

 

Eliminate Heat Sources in the Attic

Eliminate uninsulated heat ducts or heat sources in the attic. If you must have heat sources or ducts in your attic they need to be insulated at least to R-49.

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Install a Cold Roof

Some homes are difficult to ventilate as they may be built in such a way to not allow adequate insulation or proper ventilation. In this case seek a professional who understands building a cold roof. This involves putting down 1 x 3 spacers on top of your existing sheathing and then installing a new plywood or OSB roof on top of the spacers. This will create an air gap to draw warm air along the top of your existing roof and out the ridge. You will need to utilize an eave edge vent along with your ridge vent.

A cold roof is not a perfect solution. Ice dams may still form especially in valleys where snow gets trapped for long periods of time. Use of an adhesive ice and water barrier is recommended over the entire roof and in many cases a double layer in valleys and the first 12 feet of the roof.

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Secondary Ways to Drain Roofs with Ice:

1. Rake the snow off your roof with a special roof rake. Keeping the snow off the roof will eliminate ice dams. Raking a roof after ice has formed is next to impossible.

2. Have the ice steamed off the roof. Avoid pressure washers as they will remove granules and destroy your roof.

3. Install Ice Dam Cutter. Ice Dam Cutter is a permanent heated aluminum bar system going from your eave towards your ridge. This keeps a path open for melting snow to flow off the roof.