Founder | BPI® Energy Auditor Certified Professional

You’re probably wasting 35% of the energy in your home without even knowing it, and the little can lights in your ceilings can sometimes have a lot to do with it.

Insulating and air sealing your recessed attic lights is a sure way to reduce your home’s energy usage and lower your monthly utility bills. By insulating and air sealing your lighting fixtures, you’re limiting the amount of heat that escapes through these often overlooked areas.

We often overlook the disadvantages of uninsulated recessed can lights—however, there are several reasons why fixing this issue makes sense.

So we took the time to develop this guide to help you insulate and air seal your can lights. Here, you’ll find everything you need to know about recessed can lights insulation and air sealing, including the best supplies for the job and a simplified guide for DIYers.

We also built a pretty slick home air sealing calculator that uses your own utility bill (and other factors) to show a wealth of data on the benefits of air sealing. You can find that here.

Table of Contents

How Do You Insulate Recessed Can Lights?

You can insulate your can lights by swapping older fixtures with newer ICAT-rated fixtures, covering them with a fire-rated insulation cover, and then applying spray foam. However, be cautious about insulating non-IC-rated fixtures since they may become fire hazards from overheating.

Importance of Insulating and Air Sealing Can Lights

We’re all guilty of giving recessed light insulation short shrift because, after all, it doesn’t seem like they’re ushering out the hot air our heating units work so hard to pump into our homes. But unfortunately, this oversight is a big mistake because these light fixtures are notorious for leaking the conditioned air inside your home.

If you don’t believe it, place a smoke stick next to the tiny holes inside your can lights, turn the bulb ON and watch how much smoke goes through these little holes. Surprising?

Your HVAC unit needs to work more to replenish this lost heat, which eventually raises your energy bills.

Several reasons to insulate your attic can lights include:

You require more heat without insulation – a lack of insulation is not the only culprit in creating a need for more heat or cooling in your home. The uninsulated metal housing your fixture comes in gives way for the hot air to rise into your attic. This heated air gets trapped in the attic or seeps through any cracks. A higher energy bill ensues since your heating and cooling unit needs to recover the lost heat.
Insulation saves energy – more power is needed when the light’s heat escapes through the light housing side. A unit of electricity costs 13.72 cents per kilowatt-hour (kWh). Running your air conditioner longer won’t bring down the cost. Insulation takes care of this problem.
To prevent drafts – when discussing the efficiency of different HVAC systems and how much energy they use, drafts refer to the amount of heat that escapes through windows or other openings. Uninsulated can lights help this warm air escape through the attic, which raises the energy bill, as mentioned.
To prevent ice dams from forming on your roof – ice dams are a common phenomenon occurring whenever the edges of the roof have a temperature difference from the roof’s slope. This occurrence results because the warm air that has escaped into the attic comes into contact with the underside of the roof’s pitch. In a cold season, the difference in temperature between the roof’s slope and its edges causes ice dams to form.

Insulated can lights also help prevent another common phenomenon called the stack effect (chimney effect). The stack effect occurs when less dense, warm air from inside your house rises through the fixture leaks and escapes via the attic to the outside.

Incandescent bulbs can amplify this effect by allowing 3-5 times more air to escape through the fixture when you turn on the bulb.

What to Consider Before Insulating Can Lights

Can lights are tricky because they’re not just challenging to insulate or air seal but also because they have a lot of nooks and crannies. These areas make it challenging for standard insulation or foam products to provide cover without becoming a potential fire hazard.

It doesn’t help that there are so many kinds of can lights—from dome-shaped fixtures with recessed cans to double-lighted cans that look more like concert lighting than anything else.

That said, there are several things to remember when insulating your recessed lights. The fixture’s IC rating and air tightness are the first and most important.

IC-Rated and Non-IC-Rated Can Lights

When you seek the best can lights, you should look for those with an airtight IC rating. IC-rated means that the fixture can come into contact with insulation without overheating or becoming a potential fire hazard. IC-rated recessed lights are the standard for new homes as older homes tend to have older-model non-IC-rated can lights that depend on incandescent bulbs.

Illustration of a can light and the two types of IC-rated insulation — Courtesy of Sioux City Journal

Unfortunately, if you have a non-IC-rated recessed light, you’ll be unable to add insulation around it. But don’t worry, it’s not as bad as it sounds.

You can swap these with a newer, IC-rated can light and use insulation to keep the heat within the fixture. Or you can do what most people do—build insulation covers with leftover materials from another project.

The Fixture: Does It Have a Temperature Control Switch?

The temperature control switch is a device that will turn off the light if it senses a rise in temperature above a set limit, usually 194ºF. This little feature helps prevent fires, especially when you’re a big fan of incandescent bulbs.

If the light fixture does not have a temperature control switch, insulating it may not be a good idea, as you risk damaging the wiring and drastically reducing the bulb’s life with too much heat.

How Much Heat Can the Wiring Take?

Another thing to consider when deciding whether to install or insulate can lights is how much heat the wiring can take. Wires installed inside the can lights are usually covered with a sheath made of PVC, which degrades when there’s too much heat.

A recessed light on a tabletop — Courtesy of The Spruce

The degraded wires cause more problems with time, and replacement becomes inevitable. You may need to contact an expert to replace the wiring going into the recessed lights.

The Climate You Live In

Homes in colder climates tend to lose too much heat to the environment through the chimney effect, and your heating unit has to work harder to restore that heat loss, which eventually costs more energy. Insulation is necessary to keep these costs low during the cold season.

Consider Professional Help If Electrical Work Is Involved

Unless you have an excellent DIY background in electrical, always get a professional for the job. Installing or insulating can lights comes with electrical work and is an exact process. Hiring a professional to do the electrical will prevent mistakes and potential physical hazards.

Types of Recessed Lights

The three most common recessed lights are incandescent, CFL, and LED. Each light type has different insulation requirements, so choosing a suitable insulation material for your can lights is only half the battle.

Incandescent lights are the oldest and least efficient form of artificial light and the least expensive. The biggest concern with incandescent lights is that the bulbs aren’t very efficient. In addition, the heat produced by incandescent lights typically causes the entire fixture and the attic to heat up, leading to problems like ice dams and high energy bills.
CFLs have a longer lifespan than incandescent lights and use less energy but still produce considerable heat. Therefore, putting insulation behind the CFL is often a good idea if you choose between incandescent light and a CFL.
LED lights emit very little heat. The Department of Energy found that LED lights consume 80% less energy than traditional incandescent bulbs by converting 80-90% of energy into light.
So, in some ways, they don’t require as much insulation as incandescent and CFL lights. However, their heat sinks can get hot, so we recommend treating them like incandescent bulbs and insulating them.

A homeowner screwing a LED can light into a fixture

Recessed lights come in different styles and wattages depending on how much light you need. A recessed light that directs light downwards is called a downlight. You may know them as drop, hidden, or ceiling lights.

How To Insulate and Air Seal Can Lights (for DIYers)

We can safely conclude that despite their value in residential and commercial applications, can lights are not as energy-saving as they might appear.

To make them more efficient, you can insulate and seal them to keep heat inside the fixture. This process is a reasonably easy project, but it requires careful cutting.

Once again, contacting licensed insulation and electrical contractors is vital to getting the job done if you’re not well-versed in such DIY projects. Attics are messy, dark, and dusty and require a little skill to maneuver in your project.

A worker lifts a batt of rockwool insulation off a stack as he readies it to be applied to an attic ceiling

The steps below are for people with some background experience in DIY projects.

What you’ll need:

A pair of utility scissors – You will need a sharp pair to cut the insulation.
A ladder – You will need this to climb safely.
A tape measure – Tape measures ensure you cut your insulation at the right length.
A can light insulation kit – A premade kit ensures you have everything you need (a new IC-rated fixture, bulb, screwdriver, and an insulation cover).
A dust mask – This mask protects your lungs from dust and fine glass particles (if you’re cutting any fiberglass).
Gloves – You will need these accessories to make sure you are protecting your hands.

1. Take Out the Bulb From the Fixture

Cut the power to the fixture and take out the bulb. Before insulating your recessed lights, you want to ensure they are off. This step applies to all your DIY projects that involve electricity. If not, you risk an electric shock or the insulation catching fire.

2. Pull Out the Fixture and the Trim Ring

If you can’t get the trim ring off, you can use a utility knife to cut around the outside of the ring. Wear safety goggles and gloves to avoid injury to your eyes or hands. Try to avoid cutting the actual plastic of the bulb; you’ll need that to reseal the fixture later.

If you’re having trouble removing the trim ring, you can try warming up the plastic with a hair dryer to make it more pliable. If you’re working with a bulky light fixture that won’t budge, you can use a reciprocating saw to cut around the fixture and then pry it out with a crowbar.

3. Swap the Old Non-IC-Rated Fixture With a New IC-Rated One

Before you start insulating and air sealing can lights, it’s essential that the existing fixture is IC-rated. That’s because newer IC-rated fixtures will spare you the effort. You only have to focus on installing the fixture and applying insulation.

There are several kinds of IC-rated fixtures, but since it’s your attic, you probably need more than just one. The Ensenior 6 Inch Ultra-Thin LED Recessed Ceiling Light is great for sprucing up your home with a modern, sleek look.

But what we like the most about them is how easy they are to install. These fixtures don’t need canned enclosures. Instead, all you have to do is cut a fitting hole in the surface and use their spring clips to hold them securely in place.

LED bulbs also power them, and the junction box is thermally protected. That means you can insulate the fixture without problems.

4. Make a Ceiling Finish Clearing on All Sides of the Can

Next, you will need to clear the finish on the ceiling, approximately 12 inches (30.48 cm), on all sides of the can light. This clearance will expose the insulation, which needs to be out of the way when installing the protective cover.

By the way, cleaning your attic will make the work easier. A cleaner loft will be more accessible to insulation work than a filthy one.

5. Find a Fireproof Cover and Make the Cutouts for the Wires

If you’re using a non-IC-rated can light, you’ll need to cover it with a protective cover that can be insulated. You will place the cover over the electrical components of the fixture, much like an extra can for your recessed lights. There are many protective covering types made of fiberglass or other materials available.

Fiberglass is a good choice if you’re sealing a new can light. It’s easy to find and relatively inexpensive. On the other hand, polyethylene is lightweight, easy to find, and affordable. As for the cutouts for the power cords, make them a fraction larger than the cord itself so they can slip easily into position.

6. Seal the Protective Covering With Sealant or Spray Foam

After you’ve attached the covering to the can light, you’ll need to seal it with an insulation sealant or spray foam. With an insulation sealant, you’ll need to apply it to the joints of the covering.

Alternatively, with spray foam, you can apply it directly to the surface of the insulation cover. Spray foam is much better than most other sealants in terms of thermal performance.

So you’ll ensure highly effective insulation and air-sealing by sealing the covering with spray foam. However, if your can lights are not IC-rated, it’s probably best to leave them without insulation.

7. Apply a Layer of Caulk to the Ceiling Cutout

Next, apply a layer of caulk around the cutout to make contact between the attic and the fixture’s trim air sealed. You can use a paintbrush to push the caulk into the corners and ensure a nice, smooth finish.

A homeowner applies caulk around the cutout for a can light in the ceiling — Courtesy of the Department of Energy

If you’re working with a light fixture that runs hot, like incandescent bulbs, you may want to line the inside of the cutout with silicone caulk with a lower thermal conductivity to reduce the heat transfer further.

Note: If you’re sealing several cutouts, you may need to use multiple tubes of caulk to finish the job. If you’re working with fewer fixtures, you may be able to get away with one application.

8. Push the Trim Ring Back in Place

Put the trim ring back in place and ensure it’s evenly seated against the ceiling. It’s a good idea to use a screwdriver to push the clips into place if you’re working with an incandescent light fixture. Ensure that all the fixtures’ electrical wires are in their proper areas and not just stuffed inside.

Lastly, put the bulb back in place and turn the power back on. If it works, you’re good to go. If it doesn’t, check your wiring to ensure you didn’t miss anything.

And that’s how you complete a recessed light installation. As you can see, insulating your attic recessed lights is relatively easy, with a slight cost implication and big thermal rewards.

What Can I Use To Insulate and Air Seal Around Can Lights?

When choosing insulation or sealant for your recessed lights, look for a product specifically designed for this purpose. Some sealants or caulks will work for some time but eventually crack and fail. Other sealants can crack or melt if they are too close to the heat of the lighting fixtures.

Most insulation products can be cut to size and fit around any recessed light, making them a good option for DIY projects. Before choosing a particular type of insulation, ensure it is suitable for indoor use.

Recessed Light Housing

Illustrated diagram of the components of a ceiling can light — Courtesy of Fine Homebuilding

The housing is the box that attaches to your ceiling and holds the light fixture. These covers go over the entire backside of the fixture and can be insulated to ensure there’s no air leakage.

Special housing designed explicitly for your recessed lights can spare you time and effort since they’re thermally protected and ready to go into direct contact with insulation.

In addition, recessed light insulation covers give the light fixture a finished appearance, functioning as a lamp cover that hides all the wiring and other components.

Fiberglass Insulation

Fiberglass is one of the most commonly used insulation products for many home improvement projects. It’s a great cover option for recessed lights and one of the most affordable choices on our list.

Fiberglass insulation boards consist of tiny glass fibers spun together to create a fabric-like material. Fiberglass insulation can also be mixed with minerals and fibers like mineral wool to make more robust insulation. It’s very lightweight and easy to work with as long as you wear a mask to prevent breathing the contaminants.

You want fiberglass with an R-value of R-49 in the attic (for a cold home). The R-value is a measure of how difficult it is for heat to pass through a material. The lower the R-value of an insulator, the more easily heat can pass through it.

In your project, 2-4 boards of UXELY Fibreglass Plate Sheet would suffice to build an insulation box around one fixture.

UXELY fiberglass plate sheets are perfect for making lightweight, durable boxes that can be insulated later. In addition, they come in a wide range of thicknesses so that you can choose the perfect one for your project.

The bulb’s heat adds to its strength due to its thermoset epoxy resin binder, making them durable and easy to bind into a box with gorilla glue. And if you’re worried about the risk of electrical shock when working with the fixture, it will not conduct electricity.

Mineral Wool

Mineral wool (rock wool) is an excellent insulation material if you’re looking for a more affordable way to insulate your can lights. Mineral wool comprises a mixture of minerals and fibers pressed together to create a dense and lightweight board.

These boards can easily withstand temperatures above 1,200°F (649°C), making them a suitable fire-resistant material to construct your insulation boxes.

A technician installs rock wool insulation around a recessed can light in a ceiling — Courtesy of Lowe’s Canada

The mineral wool board is usually covered in paper or another decorative finish to make it look more appealing. You can use it in many different ways for recessed lighting. One of the most popular is to cut pieces of insulation and make boxes that you can seal with spray foam or other sealants.

Ceramic Tiles

Ceramic tiles are one of the easiest ways to construct insulation around can lights, and they’re also one of the cheapest. Ceramic tiles are usually clay or a combination of clay and minerals, and builders typically use them for walls, floors, and ceilings.

Ceramic tiles have a flame spread index under 25 (or CLASS A, if you like). This index means they won’t catch or exacerbate the fire spread in your attic.

Spray Foam Insulation (Sealant)

Spray foam insulation is an excellent option for can lights, but it’s often one of the most expensive. On the other hand, it’s also one of the most effective, so the cost is usually worth it. Spray foam insulation is filled into a spray gun and then sprayed into walls or ceilings.

The spray then forms a dense, expanding substance that guarantees to cover every tiny hole. Once hardened, it creates a robust and airtight barrier that helps prevent heat loss.

A can of Great Stuff Smart Dispenser Pestblock will get into the tight spaces around your insulation cover, leaving no room for air to escape into the attic.

It creates an airtight seal around the insulation cover, which keeps your home warm and cozy. Plus, the sealant dries tack-free in 20 minutes, so you can turn the lights back on soon after.

The only downside to using foam sealant is that it hardens around the insulation cover and makes it difficult to remove the outer case if you need access to the fixture’s internal components. If you intend to access the wiring afterward, it would be wise to use heat-resistant caulk.

Conclusion

You have several options when insulating and air sealing your can lights. It may seem like a lot of work, but insulating and air sealing around recessed lighting is worth the effort. Not only will it help you save money on energy bills, but it will also keep your home more comfortable.

Insulation can also help reduce indoor air quality issues caused by poor insulation and maintain consistent temperatures throughout the year. Finally, you will help reduce the increasing energy crisis, putting further strain on our already overburdened earth.

Can Lights: Ultimate Guide to Insulating and Air Sealing