The Recessed Light Box and Joist in the Attic Leaks Air

Air Leaks

• The gap between a recessed light fixture and the drywall of your ceiling can allow unconditioned air from your attic to enter your home. Larger fixtures often are mounted to a ceiling joist, creating leaks around the joist. Drafts in the attic around your fixtures or dirty insulation and small piles of dust around the fixture are common indicators of leaking air.

Sealing

• You can seal small gaps around your recessed lighting fixtures and ceiling joists using caulk. Clear insulation and dirt around the fixture, and then apply caulking to the gap between the fixture and the drywall. Unless your lighting fixture is rated IC, you should not use spray-foam insulation to seal gaps in recessed lighting. The most effective method for sealing a recessed lighting fixture is to replace it with an airtight fixture or replace it with an unrecessed model.

Insulation

• Recessed lights generate heat that poses a fire hazard if insulation is allowed to come in contact with the fixture. If your fixture is rated IC, it is designed to come in contact with insulation and you can seal it using spray-foam insulation. However, many older fixtures are not designed for direct contact with insulation. To seal and protect this type of recessed light, use wooden boards or a circular metal band to separate the recessed lighting fixture from the insulation around it. The Department of Energy recommends maintaining a minimum gap of 3 inches between recessed fixtures and the surrounding insulation. Use spray-foam insulation or caulk to create an airtight seal between the insulation barrier around the fixture and the ceiling.

Considerations

• If your home uses recessed lighting with incandescent bulbs, you can install sealed fixtures designed to accommodate compact fluorescent bulbs to further increase the efficiency of your home without changing the quality of your lighting. Recessed fixtures that are not rated IC cannot mount insulation or a reflective barrier above the fixture. If these lights are located near the eaves of your roof, the energy loss through this gap in your insulation can contribute to the formation of ice dams during the winter. This condition occurs when heat escaping through your roof causes snow to melt and refreeze into a dam of ice. This dam allows water to pool on your roof, where it can enter your attic and damage your home.