IC-rated recessed lights, non-IC cans and insulation over them

Why a light fixture matters in the attic

A recessed light, or "can", is a metal housing set into the ceiling with most of its body sticking up into the attic. From the room below you see a neat trim ring. From the attic you see a can surrounded by whatever insulation is up there, and that's where the question starts: some fixtures are built to be buried in insulation and some are not. IC-rated recessed lights are the ones that are.

Older Bay Area houses that got a kitchen or living room remodel decades ago often have a row of them, and in some cases nobody has looked at the attic side since the day they went in.

IC-rated, non-IC and AT: what the letters mean

The California Energy Commission's compliance manual quotes the clearance rules from California Electrical Code Article 410.116:

• Non-IC (not identified for insulation contact): all recessed parts must be at least half an inch from combustible materials, and "thermal insulation shall not be installed above a recessed luminaire or within 3 inches" of its enclosure, wiring compartment, ballast, transformer, LED driver or power supply.
• Type IC (identified for insulation contact): the fixture "shall be permitted to be in contact with combustible materials" at its recessed parts and supports. Insulation can go right over it.
• AT (airtight): a separate rating about air leakage, not heat. The Energy Code's test for an airtight luminaire is air leakage under 2.0 cubic feet per minute at 75 pascals, tested to ASTM E283.

A fixture can be IC without being AT, and many older IC cans leak plenty of air around their edges.

How to read the label

The compliance manual gives a straightforward method. IC-rated fixtures "usually have an Underwriters Laboratory (UL) sticker or stamp on the inside of the housing that says 'IC' in some form," and "the lamp will likely need to be removed to properly view the housing." If you look, turn the light off at the switch first and let it cool. Then:

• Look for the IC marking inside the housing.
• Look for slits or holes. The manual says plainly that if the housing has them, "it is not IC rated." From the attic side, a can with vent slots or open holes in its top or sides is a strong clue.
• When in doubt, it's non-IC. "If it cannot be determined whether a fixture is IC rated or not, it should be assumed that it is not."

Why a non-IC can under insulation is a problem

The manual doesn't soften this: "Recessed cans that are not IC rated present a serious fire hazard if they are surrounded by any flammable material because of the heat generated by the fixture." A Department of Energy guide for homeowners adds that kraft-paper facing on fiberglass batts shouldn't touch a recessed light fixture, and that loose fill shouldn't cover recessed fixtures unless they're rated IC and airtight.

The usual old fix, damming insulation away from the can, has its own cost. The manual notes it leaves areas of the attic floor with little or no insulation, "where heat gains and losses are high."

What Title 24 asks when you add insulation

Adding or replacing attic insulation counts as an altered ceiling under the 2025 Energy Code, and one of the four possible requirements is about recessed cans. In the manual's words, in the climate zones that apply, cans "shall be covered with insulation to the same depth as the rest of the attic floor," and fixtures not rated for insulation contact "must be replaced or retrofitted with a fire-proof cover that allows for insulation to be installed directly over the cover."

Whether it applies to your house depends on your zone and how much insulation is there now. Tables 9-8 and 9-10 of the manual give this pattern for the zones our cities sit in:

• Zones 2, 3 and 4 (the North Bay, the cities along the Bay, the Santa Clara Valley): the recessed-can requirement applies when the existing attic insulation is below R-19, and not when it's R-19 or more.
• Zone 12 (the inland East Bay): it applies at both levels.
• R-38 or more already in place exempts the job from all four requirements, as do a few other conditions such as knob-and-tube wiring that stays in the attic.

The complete zone table, with every branch, is on our Title 24 page. The manual also says the requirements are checked by the city's building department, not by a third-party rater.

Fire-rated covers and the thermal-switch catch

A fire-rated recessed light cover is a dome or box that sits over the can on the attic side, sealed to the ceiling around its edge, so insulation can go up to it and over it. The manual allows covers only under a condition: the fixture "must have a thermal switch," which cuts power if the temperature gets unsafe. And if nobody can tell whether the fixture has a thermal switch, the manual says to assume it doesn't, which means a fire-rated cover can't be used. In that case the remaining route is an IC-rated replacement housing.

LED bulbs and retrofit trims

A common assumption is that switching an old can to LED makes it safe to bury. The manual doesn't offer that as a route. For a can that isn't IC rated, it names two: an IC-rated housing "designed for retrofit applications", or a fire-rated cover on a fixture with a thermal switch. Retrofit trim kits appear in the manual for a different purpose: making an existing IC-rated can airtight. If a product's packaging says otherwise for your fixture, that's a question for an electrician, not for an insulation crew.

Who does what

Replacing a fixture housing is electrical work, and it belongs to an electrician. Sealing air leaks around fixtures, ducts and top plates is covered on our air sealing page, and the insulation itself on the blown-in insulation page. If you're weighing which insulation material to put near hot fixtures, is attic insulation flammable? compares them.

When you'd like someone to look at the attic side of your lights, book a free inspection, or send photos of the cans from the attic and from below.