Help! My Attic Gets SCARY COLD in the Winter

Aug 30, 2011 by

The attic definitely qualifies as one of those “out-of-sight, out-of-mind” areas. Why worry about this space if you don’t need to spend but a few moments up there every once in a while? The truth is that the attic is a lot more important than most people know. It plays a major role in a home’s overall energy performance –how much it costs every year to keep your living space comfortable.

Too Cold, Too Little Protection

If your attic hasn’t had the benefit of an energy upgrade, the scariest time to go up there is probably on a cold winter day. A journey of just a few steps takes you from a comfortable environment into a realm that’s scary cold. What makes it scary is the scant protection from outside air temperatures in the typical attic.

According to research done by the U.S. Dept. of Energy (DOE), the average unimproved attic has just R-19 insulation –the insulation value of a 5 ½-in.-thick fiberglass batt. The DOE recommends R-49 or better for good energy efficiency and interior comfort in northern states.

Energy Loss Explained

Heat always moves from warm to cold, so the warmth in your living space can easily make its way through a minimal amount of attic insulation. Air convection accelerates this energy loss–the natural tendency of warm air to rise to the highest point in a confined space.

The same convective pressure that causes a hot air balloon to gain altitude is pushing the warmest air in your house up into the attic, through numerous air leaks around electrical outlets, inside walls, around the attic hatchway, and through other gaps and cracks that occur as a result of the construction or remodeling process.

Unfortunately, the fiberglass and cellulose insulation used to insulate most attics does little or doesn’t do a thing to stop air movement. So the upward escape of air that you paid to heat continues despite the insulation in your attic.

As warm air exits out the top of the house, the negative pressure created by this action sucks cold exterior air in through lower areas of the house –most often through basement and crawl space areas. This so-called Stack Effect is the main culprit in many houses that haven’t had energy-saving upgrades.

The exfiltration of warm interior air through the attic causes the infiltration of cold outside air through basement and crawl space areas. This explains how cold drafts occur in a typical house.

Air Sealing and Insulation Make Winter Comfortable

Fortunately, there are proven ways to short-circuit the Stack Effect and enjoy conditioned air inside while keeping unconditioned air outside the house. The first step in this energy-saving upgrade is to have your attic professionally air-sealed, maintaining the warm interior air.

While basement, crawl space and conditioned spaces can be air-sealed in addition to air sealing the attic, the attic is by far the most important location for this upgrade. Once air leaks are sealed, additional attic insulation can be added. In most cases, this extra insulation can be applied directly over existing attic insulation. Attic storage platforms may need to be removed or elevated to accommodate the additional insulation, but these details can be figured out through a discussion with an experienced home energy improvement contractor.

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