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Q Our kitchen has a cathedral ceiling with IC (insulation contact) rated recessed lights. You can see the frost on the roof melt over each of them on cold mornings. Can I seal the holes in the cans with tape to make them more energy efficient?
R.F., Columbus, OH
A Your fixtures aren’t airtight unless they have an “airtight” rating.But don’t plug the holes (see photo). Manufacturers submit fixtures to Underwriter’s Laboratories (UL) to receive a safety rating for their designated use. (You’ll see a UL rating somewhere on the fixture.) Altering the fixture in any way may compromise its margins for safety.
But you raise a real issue. Recessed lights in cathedral ceilings waste the heat from the light bulb and the warm air that leaks through the fixture. Even worse, moist, warm air will flow up against the cold roof sheathing (see photo). Chances are that it’ll condense there, wet the wood and eventually cause rot. Unfortunately, there isn’t any easy way to know if you have moisture problems and rot until you find water dripping from the ceiling, stains or soft spots in the drywall. The fix is expensive.
Airtight recessed fixture
(IC remodeling type)
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Builders often try to prevent the problem by leaving a 1- to 2-in. airspace for roof ventilation (see photo). Roof venting can help dry the wood again in warmer weather, and it’ll flush out some of the moisture in cold weather. But it often doesn’t work well.
The best solution is to avoid putting any recessed lights in cathedral ceilings. However, if you want them, use type IC “airtight” fixtures (available for $20 at lighting stores and home centers). These fixtures are sealed to stop airflow. In addition, they have gasketed edges to seal them to the drywall.
Replacement can be challenging. If you’re lucky, you can pull the old mounting bracket out through the existing hole. Otherwise you have to tear open the ceiling.We recommend that you hire a licensed electrician for this tricky job.
