Venting the attic now is a good idea

Home Work

August 30, 1998|By Karol V. Menzie and Ron Nodine

ATTIC VENTING. It's one of those subjects that simply makes most people's eyes glaze over, like a review of calculus or a lecture on the popularity of corduroy through the ages. But it's a topic that bears thinking about, especially as winter approaches.

Not considering it can have consequences that are foolish -- such as wasting money on energy -- or dire -- such as condensation buildup that can ruin a roof.

Do you know if your attic space is properly vented? Or if it should be vented at all? If you live in a newer house, built after 1970 or so, adequate ventilation of the attic space would have been specified in the prevailing building code. If, however, your house is older, there may not have been any building code in effect, or it may not have been enforced at the time.

So the simple answer to the question is yes, the attic needs to be vented.

It needs to be vented in summer to allow some of the heat to escape. On a warm day, the temperature in an attic can reach 140 degrees or more. Higher attic temperatures can reduce second-floor air-conditioning efficiency and shorten the life span roofing materials.

In winter, the attic needs to be vented to equalize the inside temperature with the outside. Otherwise, air that is heated from the living space below can cause various problems.

One such problem is condensation: when the air in the attic is warm, and the temperatures outside are freezing, moisture in the warm air will condense on the underside of the roof decking. Over a period of time, the wood will mildew and deteriorate. Any sign of mildew on the underside of the roof is a good indicator that you have this problem.

Another potential problem is ice damming. When there is snow on the roof, the heat from below will melt it over the attic space. The water runs down to the overhang where there is no heat and freezes again. The ice buildup on the edges creates a damming effect that will make a perfectly good roof leak.

To prevent all these problems, you want the temperature in the attic to be as close to the temperature outside as possible. Most older homes have gable vents (at the peak of the roof) and soffit vents (on the underside of the overhang). This lets air flow upward and out the ends.

The best system is a combination of a ridge vent with soffit vents, which allows air to circulate and flow evenly across the entire roof. Most newer houses are built with ridge vents. If you have an older house and are planning a new roof, you can have your contractor install one. Make sure the soffit vents are clear -- so air can get in -- or the system won't work.

A common mistake Ron sees a lot is when people add insulation to their attic (which is good), they cover the space where the roof meets the outside wall that is supposed to allow air in (which is bad). You can install baffles that keep the insulation from blocking the space where the air needs to circulate.

If your situation doesn't allow for a ridge vent, you can install a turbo or power vent in the roof. These work especially well in summer to let heat out.

Winter is difficult enough to get through without worrying about your roof. A little thought now will keep you cozier at home when the chilly stuff arrives.

Ron Nodine is owner of American Renovator Inc., a Baltimore design-build remodeling firm, and president of the Remodelers Council of the Home Builders Association of Maryland. Karol Menzie is a feature writer for The Sun.

If you have questions, tips or experiences to share about working on houses, e-mail Ron at or Karol at Or write c/o HOME WORK, The Sun, N. Calvert St., Baltimore 21278. Questions of general interest will be answered in the column; comments, tips and experiences will be reported in occasional columns.

Pub Date: 8/30/98

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