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Best Practices

Recessed Lights and Air Leakage

Tips for insulating and air-sealing around this notoriously leaky lighting fixture type to save energy, improve comfort, and protect building materials over time

Get an air-sealing plan in place to address recessed can light fixtures at installation. The right product and detailing can reduce energy losses and prevent bigger problems caused by air leakage and bulb heat.

I’ve been on a few energy audits and assessments where the homes were built or remodeled in the late 1990s and early 2000s. Electricians working in those times were installing the traditional recessed light fixtures, also known as recessed cans or pot lights. Generally, this type of lighting fixture doesn’t have any issues when installed inside the air and thermal boundaries of the building envelope. But it can be problematic when the can lights end up displacing insulation and interrupting the continuity of the air control layer. In this post, I’ll discuss the challenges with this type of lighting and share ways to improve the performance of a home that has existing recessed cans.

IC rating label
Left photo, the IC or insulation contact decal on a recessed light fixture; right photo, the location of the thermal overload protection device

Recessed lighting was first used in commercial contexts in the 1940s. It quickly transitioned to the residential market and is still widely used. Today’s can lights are required to have labeling that identifies whether they can be in direct contact with insulation; this rating is denoted “IC” for insulation contact, and a label will be found on the fixture housing. Non-IC-rated recessed light fixtures are required to maintain a 3-in. clearance to all insulation. IC-rated fixtures contain a temperature sensor or thermal overload that will interrupt power to the light bulb should the temperature rise above a safe level.

Recessed light mounting bracket

The traditional recessed light fixture has some sort of mounting bracket, like the one in the above photo. Often these brackets are adjustable so that they can be installed in 16- or 24-in.-center framing. They also contain a junction box, where the household wiring is terminated. Junction boxes are required by code to remain accessible. This is accomplished in a…

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One Comment

  1. iconoclast2222 | | #1

    Sealing existing can lights and building foam boxes brought to mind a recent discovery of mine. In a different life I am a sculptor working mostly in clay. I have investigated using various derivatives of papier-mâché. I stumbled across a mache product used by taxidermists. The exact proportions of materials is not easily ascertained but they seem to be IMHO less than half paper pulp, less than half plaster and maybe a small amount of glue. It’s mixed with water and applied like sticky plaster. It’s quite strong when dry. It will fill voids quite well. Find it at

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