Wednesday, January 2, 2002

Give your attic a breath of fresh air

While people know it's important to seal drafts in the living area of their home for winter comfort, many don't know it's just as important to keep their attic breathing freely to keep a home warm.

A poorly ventilated attic can create winter time problems that reduce the effectiveness of insulation, cause roof damage and create rotting in roof trusses and other timbers. Good attic ventilation is as important as enough insulation.

Although winter may seem cold and dry, unseen moisture escapes from your home's living spaces and this moisture can condense in your attic insulation, reducing the ability of the insulation to keep heat in the home where it belongs. Venting moist air out of the attic keeps the insulation dry and the home warm.

If an attic is not properly vented, heat escaping from the home is trapped and can increase the air temperature in the attic to melt snow on the roof. This melting snow will refreeze when it reaches the eaves, causing ice dams, which, if severe enough, may cause the melting snow to back up under the shingles.

Often so much water backs up that it drips through the roof deck into the attic insulation. Enough moisture buildup in the insulation will eventually damage interior ceiling and wall surfaces. In addition, moisture from condensation and ice dams can accelerate damage to structural material in the roof and walls. Improving your attic ventilation is easy.

1. Install continuous ridge venting along the roof peak, where the hot air is exhausted from the attic. The ridge vent should be durable and weather resistant. If it's impractical to install ridge vents, several traditional roof vents (roof louvers) should be installed as near the ridge as possible.

2. Install continuous soffit ventilation strips under the eaves. These soffit vents allow fresh, cool air to enter the attic. Because air will be drawn in the soffit vents, make sure they have a fine mesh screen to prevent insects from entering. Soffit vents should be made of aluminum or plastic to prevent rusting.

3. Inside the attic, install attic ventilation channels between the rafters to maintain unobstructed air flow over the insulation. Without these ventilation channels, a good flow of air up and out the ridge vent won't occur. These vents also prevent windblown insulation from plugging or blocking the air flow from the soffits.

Ventilation channels traditionally have been made of cardboard or foam, but are being replaced by more durable and easily installed rigid plastic products. ProVents, from ADO Products in Minneapolis, are made from black recycled plastic and cost less than $2 each. Improving a home's attic ventilation, particularly in homes older than 10 years, is one of the simplest and most important tasks a homeowner can do to improve energy efficiency and prevent long-term moisture problems. Ask your local building material retailer for more information on ventilation and insulation products. For information on ProVent from ADO Products, call (800) 666-8191.

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