Why and How to Insulate Your Garage (Complete Guide)


If you decide to insulate your garage. Let’s go over some things you need to know before starting the project and then look at the insulation process itself.

Insulation acts as a barrier to heat flow. It is necessary for keeping your garage warm in winter and cool in summer. A well-insulated garage provides year-round comfort, lowering cooling and heating bills. Insulation also adds soundproofing.

There are many things to consider when deciding the type of insulation and cost of the project.

Should Garage be Insulated?

Insulation is a must if you need a warmer or cooler place to work on DIY projects or convert the garage to a living area or home gym, etc.

Adding insulation to a garage will help moderate temperature extremes. Insulation helps maintain the temperature, whether hot or cold. Insulation prevents cold or warm air from escaping through the walls, ceiling, and doors.

Benefits of Insulating Garage

Insulation slows the transfer of heat through the wall. Walls that are shared with the house should always be insulated at least. IF the garage is actively heated or cooled, you should definitely insulate.

The purpose of insulation is to slow the conduction of heat from the interior to the outside. And vice-versa. Insulation also adds soundproofing. Saves energy and regulates temperature.

If you spend a lot of time in the garage and add a heater or A/C. Insulating the garage is definitely worth it. Because you want the heat or cool air to stay in the garage as long as possible. Running a heater or air conditioner is not cheap.

Garage insulation is especially well worth the cost if you have a room over the garage. You should insulate the garage ceiling if there is a room over the garage. If you don’t, you’ll find it very hard to keep that room warm, which can be very uncomfortable, especially if it’s a place where people spend time.

If you use the garage as a workspace or have plumbing apparatus like a washer or sink in the garage. You don’t want frozen pipes and water damage.

The most crucial area of the garage to insulate are the ceiling. The exterior walls and — a place many homeowners forget — the garage door.

Garage doors are big and act as a fourth wall.

Insulating your garage walls and ceiling to energy conservation recommended standards won’t make a difference Unless you also have an insulated garage door.

Studies have shown that replacing a non-insulated garage door with an insulated one can reduce heat loss through the garage by more than 70%. Even if your garage is unheated, that could mean a garage that’s warmer by as much as 20 degrees Fahrenheit.

Does It Make Sense to Insulate an Unheated Garage?

Insulation works best in climates that see drastic temperature swings.

Aside from regulating the temperature inside the garage, insulation also helps manage humidity. Relative Humidity levels, also known as RH, measures the amount of moisture in the air.

High or low amounts of humidity can create all sorts of issues and even damage. Depending on what you use the garage, this could be a problem or no big deal.

Humidity, which is very common in uninsulated garages, breeds rust and mold. With a well-insulated garage, you don’t need to worry.

Should a detached garage be insulated to help control humidity levels? It depends on what you use the garage for. But 90% of the time, I’d say yes. Even if regulating humidity level isn’t a big deal when you build your detached garage.

Someday you may want to store something valuable or use the garage for some other purpose where humidity could be a problem. I’d recommend playing it safe and planning ahead by including insulation in construction plans.

Best Reasons to Insulate a Garage

  • Prevents air leakage
  • Stops heat transfer
  • Saves energy costs
  • Temperature regulation

Some people may have more of a need to insulate their garage than others—for instance, someone who works in their garage often for vehicle repairs or other reasons.

Suppose you are in your garage space often for any particular reason. In that case, it only makes sense that you would want the space to be comfortable. And in some cases, people are interested in turning their garage into a living area.

If you are in your garage often working etc., you want it to be warm/cold. Insulation may not be enough. You need a heating/cooling source too.

Unless your garage is heated, insulation will have a limited impact on the temperature inside your garage in freezing climates. Insulating the garage won’t make it much warmer.

Why You Should Insulate Your Garage

The most notable benefit of adding insulation in your garage is the ability to have better control over the temperature. Yet, there are many other benefits you can expect from this easy DIY improvement.

One significant benefit is the amount of energy you can save. This can equate to a dramatic drop in your energy bills long after the insulation has been installed.

Another lesser-known benefit is that it can help create a soundproof environment. Keeping sounds out or in, depending on your situation.

For example, if you live on a noisy street, garage insulation can help quiet the traffic’s loud noise. Or, you are using your garage as a workshop or you learning to play some instruments. Insulation will help prevent that noise from becoming a nuisance to your neighbors.

Using a Garage a Year Around

If you insulate your garage, then you can do a lot more than protect your vehicle. You can use the space to put your home gym inside, use it as a fun area for the kids or get to work on various projects.

In the summer or winter months, the insulation and heating /cooling will keep the temperature like what you have inside your home.

How Do I Choose Garage Insulation?

Insulation products come in two main categories — bulk and reflective — which are sometimes combined into a composite material. Let’s look at the different types and materials below.

What R-Value Insulation Do I Need for the Garage?

R-value measures how well certain building insulation materials resist heat. So, the greater the R-value, the greater the ability to insulate. Products with the same R-value have the same insulating performance if installed as specified.

R-values can differ depending on the direction of heat flow through the product. The difference is generally marginal for bulk insulation but can be noticeable for reflective insulation.

  • Up’ R-values describe resistance to heat flow upwards (sometimes known as ‘winter’ R-values).
  • Down’ R-values describe resistance to heat flow downwards (sometimes known as ‘summer’ R-values).

Up and down R-values should be quoted when installing reflective insulation in roofs, ceilings, and floors.

Typical recommendations for exterior walls are R-13 to R-23, while R-30, R-38, and R-49 are typical for ceilings and attic spaces. See the Department of Energy’s (DOE) ranges for recommended levels of insulation below.

  • Most older homes were built with 2×4 studs. (A stud is a vertical framing piece in a wall. It’s also often referred to as a 2×4.) For these, use R-13 insulation.
  • Some newer homes (built in the last 10-15 years) were built with 2×6 studs. These require R-21 insulation.
  • Use R-40 or above thick insulation for the ceiling.

Insulation Types and Their Applications

Bulk Insulation

Resists the transfer of conducted and convected heat, relying on pockets of trapped air within its structure. Its thermal resistance is basically the same regardless of the direction of heat flow through it.

Bulk insulation includes materials such as glass wool, wool, cellulose fiber, polyester, and polystyrene.

All bulk insulation products come with one material R-value for a given thickness.

Reflective Insulation

Resists radiant heat flow due to its high reflectivity and low emissivity (ability to re-radiate heat). It relies on an air layer of at least 1 inch / 25mm next to the shiny surface. The thermal resistance of reflective insulation varies with the direction of heat flow through it.

Reflective insulation is usually shiny aluminum foil laminated onto paper or plastic. It is available as sheets (sarking), concertina-type batts, and multi-cell batts. Together these products are known as reflective foil laminates or RFL.

Dust settling on the reflective surface greatly reduces performance. Face reflective surfaces downwards or keep them vertical. The anti-glare surface of single-sided foil sarking should always face upwards or outwards.

Garage Insulation Types

Blankets (Batts and Rolls)

The most common type of insulation is batts or rolls, which are generally called blanket insulation. These are pre-cut sections of insulation while a roll of insulation comes wrapped up. Insulation rolls leave less opportunity for gaps between sections, making them somewhat more effective than batts.

Batts

  • Best for unfinished walls, floors, and ceilings.
  • It is designed for easy handling and uses between framings, such as studs and joists, making it one of the best insulation for walls.
  • Installed in pieces.
  • DIY-friendly.
  • One of the most affordable types of insulation.
  • Available either with or without paper or aluminum foil facing. Facing helps prevent interior heat from escaping and water vapor from passing through the insulation. Install the batt so that the facing is on the exposed side.
  • Standard fiberglass batts have R-values ranging from R-2.9 to R-3.8 for every inch of thickness. Still, high-density insulation batts can have R-values as high as R-4.3 per inch.

Rolls

  • Best for unfinished walls, floors, ceilings, and wherever long and continuous insulation pieces are needed.
  • Available in pre-cut widths to fit between studs and joists.
  • Come in continuous lengths ranging from 20- to 40-feet.
  • DIY-friendly.
  • Another one of the most affordable types of insulation. Comparable in price to batts.
  • Like batts, standard fiberglass rolls have R-values ranging from R-2.9 to R-3.8 for every inch of thickness. High-density insulation rolls can have R-values as high as R-4.3 per inch.

Loose Fill

Unlike blanket insulation, loose-fill has no shape, as it resembles the stuffing from inside a soft toy. It’s blown or sprayed into place with special equipment and is excellent for filling various forms or spaces.

  • Best for attics, hard-to-reach, or oddly shaped areas and already insulated spaces.
  • Usually made of fiberglass, cellulose, or mineral wool.
  • Blown or sprayed into place with pneumatic equipment.
  • Can fill wall cavities.
  • Mid-range prices when compared to other insulation types.
  • R-values range from R-2.2 to R-3.8, depending on the insulation material.

Sprayed or Foam-In-Place

One of the easiest applying methods is a liquid latex or polyurethane foam that expands and hardens to fill gaps. It is literally spread over and throughout areas by shooting the insulation at the wall with a hose.

  • Best for hard-to-reach or oddly shaped areas and already insulated areas.
  • It can be used to fill small gaps and cracks or to insulate large spaces.
  • Ideal for sealing around doors, windows, and vents.
  • Sets quickly and can be trimmed, painted, or stained.
  • Has two types: open-cell foam and closed-cell foam. Closed-cell foam is denser and thus has a higher R-value. Closed-cell foam is usually more expensive than open-cell foam.
  • Open-cell foam has an approximate R-value of R-3.7 per inch of thickness.
  • Closed-cell foam has an approximate R-value of R-6.2 per inch of thickness.

Rigid Foam Insulation

Added to the frame of the building, rigid foam insulation boards are typically used when remodeling or building a house.

  • Best for floors, foundation and basement walls, interior and exterior wall sheathing, and low-sloped ceilings.
  • It can be used to insulate almost any part of your home, from the roof down to the foundation.
  • Usually made from polystyrene, polyisocyanurate, or polyurethane.
  • Sheathing reduces heat conduction through structural elements like wood and steel studs.
  • Great insulation choice for cold climates.
  • DIY-friendly.
  • Typically more expensive per square foot than other insulations.
  • R-values range from R-4 to R-6.5 per inch of thickness.

Reflective Insulation

As the name suggests, reflective insulation reflects heat. It helps cut down on downward heat flow.

Radiant Barrier

Type of insulation reflects heat away from your home with special designs that protect against consistent, intense sunlight.

  • Best for attics, unfinished walls, ceilings, floors, and attached garages in hot climates.
  • Designed to keep your home cool.
  • Made from a reflective material such as aluminum foil over a substrate like kraft paper or foam board.
  • DIY-friendly.
  • Most often used for attics since most heat enters through the attic.
  • Not measured in R-values.

Garage Insulation Materials

Fiberglass

Fiberglass is the most commonly used type of insulation in garages.

Fiberglass is a skin and lung irritant, so always wear protective eyewear, gloves, masks, and clothing when working with fiberglass insulation.

Sold in pre-cut batts and long blankets that fit between wall studs and ceiling joists. It’s made from fine glass fibers and is most often used in batts, rolls, and loose-fill insulation.

Suppose the walls and ceiling will remain open (not covered with drywall or plywood). In that case, it’s a good idea to use paper-faced or encapsulated fiberglass batts that are wrapped in a plastic film. These will give the walls a slightly more finished look, and you won’t have the itchy fibers of the insulation exposed and ready to catch dust at all times.

  • Available in rolls (or batts) or in loose-fill, which provides flexibility.
  • Not as dusty as cellulose during installation.
  • Easily installed in many locations within the home.
  • Available in many different widths and thicknesses that promote easier installation.

Cellulose

Cellulose is loose-fill insulation. Cellulose insulation is made from recycled paper products. Manufacturers also add borate for fire and insect resistance.

Cellulose is usually blown into wall and ceiling cavities with a particular blowing machine that also aerates the cellulose and fluffs it up. Blowers can be rented.

some home centers will sometimes loan you a blowing machine if you buy your cellulose from them.

Because it’s loose-fill, cellulose is suitable only for finished garage walls and ceilings. If the garage is already finished (but uninsulated), you can install cellulose by cutting holes in the wall material, spraying the insulating into the cavities between framing members, then sealing the holes.

  • Cellulose maintains an R-value of about 3.8 per inch.
  • The density of cellulose makes it a superior sound barrier.
  • Also, cellulose is a recycled product, which maintains a very low embodied energy.
  • Cellulose offers homeowners an environmentally friendly, energy-efficient insulation option.

Rigid Foam Insulation

Rigid foam comes in 4 x 8-foot sheets and thicknesses of 1/2 inch to 4 inches. Foam insulation may be made from polystyrene, polyisocyanurate, or polyurethane, all types of plastic.

Rigid foam offers a high R-value per inch of thickness and can be cut to fit almost any space. It’s a good choice for thin walls and for insulating garage doors. Suppose you’re turning the garage into living space or a full-time workspace and want to insulate the floor. In that case, one option is to use rigid foam covered in plywood or other subfloor material.

Note: Check the fire rating on rigid foam; some types are not fire-resistant and are not suitable for exposed applications.

Spray Foam Insulation

Spray foam is excellent for both R-value and for air-sealing. As a high-end material typically used for energy-efficient construction, spray foam is overkill for most garage projects. But it might make sense if you’re converting the garage to living space.

Spray foam remains a good option for retrofits, such as:

  • Attic conversions.
  • Basement remodels.
  • Crawl space upgrades.
  • Remodeling projects when walls are opened for other reasons.

Mineral Wool

Mineral wool can refer to either rock wool or slag wool. Rock wool is a man-made material made from a combination of natural minerals. Slag wool is also a man-made material but is made from a molten metal waste known as slag. Both mineral wool insulations are naturally fire-resistant. They come as batts, rolls, and loose-fill.

Eco-Friendly Insulation for the Garage

Natural Fibers

Insulation can also be made from various natural materials, including cotton, sheep’s wool, straw, and hemp. These materials are from recycled sources and are treated to be fire, mold, and insect resistant.

Soy-Based Foams

Despite having only a small share of the market, soy-based foams are growing in popularity among consumers due to their myriad advantages, including:

  • high acoustical and air-sealing properties
  • Class 1 fire ratings
  • no off-gassing of chemicals and other materials that pose health risks
  • completely renewable composition
  • long-term resistance to degradation

Natural Wool

Another alternative insulation product is natural wool. Wool insulation offers many benefits to consumers, such as its:

  • strong moisture absorption and desorption capabilities
  • improved acoustics, as wool is a natural sound blocking material
  • lack of carcinogens, which eliminates skin, eye, or respiratory irritation during the installation process
  • ability to improve indoor air quality, as wool absorbs indoor air pollutants

Hemp

Although mostly unknown in the US, hemp insulation has found a niche among those looking for eco-friendly insulation solutions. Like the aforementioned alternative insulation types, hemp insulation offers many environmentally friendly and health safety features, including:

  • biodegradable and fully recyclable
  • contains no hazardous materials
  • can absorb a significant amount of moisture without degrading its thermal performance
  • no degradation
  • does not attract insects or rodents

Recycled Denim

It is made from recycled jeans and post-industrial denim cotton. Denim is non-toxic and non-irritating, making it easy for DIYers to install. It’s typically more expensive than fiberglass or other insulation materials.

With higher acoustic ratings than traditional insulation materials, recycled denim insulation is an excellent alternative for interior walls in bedrooms or home theaters. These products are also environmentally friendly – denim insulation does not contain harmful components like volatile organic compounds and formaldehyde. The manufacturing process is generally waste-free.

Aerogel

Eco-friendly doesn’t always mean naturally occurring. In 1931, Samuel Stephens Kistler invented aerogel, a material comprised of more than 90 percent air. It’s made by removing the liquid from silica under high pressure and temperature. You can buy aerogel in sheets or stickers that make it easy to apply. The ultra-lightweight material can cost up to $2 a foot but will save you money on heating and cooling costs.

ThermaCork

ThermaCork is a product made from oak trees’ outer bark and is natural, renewable, recyclable, and biodegradable. Once produced, the finished product actually has a negative carbon footprint. Cork reduces energy consumption and will continue to do so far longer than most insulation choices. It’s also hypoallergic, free of domestic toxins, and works to mute sounds.

Polystyrene

Polystyrene is actually a type of plastic. And although plastic is not traditionally green, it’s considered to be in this instance because the R-values are so high that it ends up saving a lot of energy. It can come in both a foam board (which adds structural integrity to walls) or a spray foam.

Some brands of glass wool, polyester, and cellulose fiber insulation contain significant amounts of recycled material.

Tip.

You can mix insulation materials and types. Just because your home already has one kind of insulation doesn’t mean you can’t supplement it with a different insulation type.

Pros and Cons of Different Types Of Insulation

  • The most common type of insulation, fiberglass batts, offer R-11 to R-13 insulation value, depending on the brand, and installing them can be a DIY project.”
  • Blown-in cellulose is popular for garage attics, and this type of insulation is also DIY-friendly. Cellulose insulation has an approximate R-value of 3.5 for each inch of insulation. For instance, a 10-inch-thick layer would add a value of R-35.”
  • Rigid foam panels can be cut to fit inside stud walls, and they come with an R-value of about 4.5 or 5 per inch. They are slightly less DIY-friendly because they can be difficult to cut precisely without leaving gaps.”
  • Spray foam insulation is dense and offers an R-value of about 6.2 per inch. Still, it can be tricky for a DIYer to install, and some types require a certified installer.

Easiest Insulation for a Garage?

Due to its solid R-Value, wide availability, relatively low cost, ease of installation, and unmessy nature, we recommend fiberglass batts or rolls for your garage DIY project.

Before Garage Insulation

It’s important to realize the value of air-sealing in conjunction with insulation. Garages usually aren’t built to be airtight and have lots of air gaps in the outdoors.

You can insulate the walls, ceiling, and door of the garage to the highest R-value possible, but if you fail to fill those air gaps, you’ll still be wasting a lot of heat.

So before insulating, go around the garage with a can of low-expanding spray foam and seal all gaps and cracks where you can see daylight. Also, make sure weatherstripping along the bottom of the garage door and along window and door frames are intact to seal against drafts.

Installing Insulation in the Garage

Estimated Time Needed

Approximately 1-3 days, depending on how big the garage is

To find out how much insulation you’ll need:

  1. Measure the area needing insulation.
  2. Measure the length and width of the area you need to insulate.
  3. Multiply the length times the width to determine the square footage of the space.

It’s recommended to buy an extra unit of insulation.

What You Need to Insulate Garage

  • Safety glasses
  • Gloves
  • Fiberglass-proof mask
  • Pants and a long-sleeved shirt

Tool List

  • Hammer tacker
  • Box cutter
  • Ladder or stilts
  • Sharp utility knife
  • Staple gun and staples
  • Knee pads, if desired

Parts List

  • Fiberglass batts of insulation for walls
  • Spray foam insulation for nooks and crannies
  • Blown-in insulation for the ceiling
  • Garage door insulation kit

In this example, we will use fiberglass matt as the primary method of insulation. We assume the exterior walls of your garage have typical wood stud framing and are without drywall.

The Walls

  • Clear out the garage and remove any obstructions that could get in the way. Make sure to clear up any dirt and clear out the stud cavities.
  • Locate any small or odd spaces, measure them out, and use the box cutter to cut these specific shapes from a batt. Always use custom pieces and do not smash, squish, or shove insulation into a tough spot. The insulation needs to be flat, evenly distributed, and securely in place to work to its fullest potential.
  • Fit the odd shapes into the wall like pegs into holes. The insulation should be appropriately deep to fill the entire space between the wall and the frame’s edges. Do this until only tall, straight openings remain.
  • Nail or staple the insulation in place, if necessary.
  • Measure and cut the batts to the necessary size and shape of the wall studs.
  • Pick a corner, start there, and work your way around the garage.
  • Place the insulation near the floor and slowly press the insulation in, but do not smash it. Work your way up the wall.
  • If gaps are remaining, cut pieces of insulation to fill the gaps.
  • Add a vapor barrier, if necessary.
  • Staple the paper face of the insulation to the stud’s side, NOT the face of the stud. You’ll need to leave the face of the stud exposed to install the drywall on top of the insulation.
  • Cut the insulation to the correct size.
  • Use a utility knife to cut excess insulation, so it fits the size of the stud.
  • Tuck the insulation in to make it easier to staple.
  • Staple the insulation all the way down the side of the stud.

Does Insulation Need To Be Stapled Down?

Unfaced insulation comes in rolls and batts designed to fit snugly between standard stud widths, so while it will stay in the stud space most of the time, it can fall out.

Some builders will spray an adhesive on the back of the stud wall and then put the batt in place. In the case of faced insulation, it comes with paper sides that fold out along the studs’ front edges and can be stapled in place. That’s the easiest way.

Cover the Insulation with Drywall

Screw and glue drywall to the stud. Do not leave the paper of the insulation exposed. This is a fire hazard.

Note 1: As mentioned, some insulation needs to be stapled or nailed in place. Others, however, use friction and force to hold in place. Check the insulation for instructions.

Note 2: Some garage walls might have electrical lines running through them. Do not place the insulation over the wiring or electrical lines. Instead, cut small slits into the insulation and tuck the electrical wiring inside of the insulation.

The Garage Door Insulation

Don’t insulate your garage walls and ceiling without insulating the big garage door, too.

You can buy insulation kits for standard metal garage doors, or you can cut pieces of rigid foam insulation to fit each door panel/section.

Keep in mind that garage doors’ structural metal ribbing is an excellent conductor of heat, and this typically doesn’t get insulated. As a result, the door’s overall thermal performance will be well below the rated performance of the insulation itself.

Air-sealing is particularly important with garage doors. Create a seal along the door’s sides and top with special garage door trim with an integrated weather seal strip. Seal along the bottom of the door with a new rubber gasket, or “bottom seal.” It’s available in various sizes to cover small or large gaps between the door and the garage floor.

  • Measure your garage door.
  • Buy a garage door insulation kit.
  • Follow the instructions in the kit.

Keep in Mind: When you insulate the door, you’re adding weight to it. You may need to change or adjust the springs to retain tension and balance to operate correctly. This is why it may be easier to get an already-insulated door or have a professional help you.

The Ceiling (Rolls or Batts)

Insulating the ceiling of your garage involves the same process as insulating the walls. Remember to use thicker R-40 insulation.

  • Prepare a sturdy and secure scaffolding, platform, ladder, or set of stilts. If necessary, grab a friend to hold the ladder.
  • Before installing the insulation, install baffles into the eave space to ensure ventilation within the ceiling and avoid moisture damage.
  • Measure, cut, and install insulation in small or odd spaces.
  • Measure the stud spaces you will be filling and cut the rolls or batts to the appropriate sizing.
  • Install the roll or batts into the ceiling, pushing the insulation up into the joists before pulling it back down into place for full and even coverage.
  • Make sure all edges are flush, and there are no gaps.
  • Fill any gaps by cutting custom pieces of insulation.
  • If required by code, staple the insulation’s facing into the joists to keep them in place.

Note: Keep insulation at least three to five inches away from any light sources. Insulation installed too close to a light fixture could result in a fire.

Safety Tip: Measure the height and width between the ceiling’s framing and pre-cut the pieces you’ll need. This will help while you’re up on the ladder.

The Ceiling (Blowing)

The simplest way to install insulation in a typical garage attic will be to blow it in.

The ceilings in most garages will already have drywall installed or plywood panels, and there’s also probably an access door. To get to the wiring, etc., you will need to be able to get into the attic to blow in the insulation.

You have to be careful to step only on the joists, you can’t step between them on the underside of the drywall, or your foot will go through. You can cut some 2-foot-by-4-foot pieces of plywood to lay across the joists to step on if you like. That’s a bit safer.

You have to be careful not to block intake vents in the eaves with insulation. When you blow-in insulation, it actually comes out pretty slow and drippy, so it’s not difficult to avoid the vents. Some builders like to cut a strip of batt insulation and use it to block the eave vents and then pull it out after blowing in the insulation.

Get a buddy to help. One person remains in the garage and loads insulation into the hopper. At the same time, the other holds the end of the long flexible hose and directs insulation flow.

Do I Need a Vapor Barrier?

A vapor barrier is a material that prevents water vapor from passing into your walls and ceilings during cold weather.

Suppose moisture from either direction builds up within stud or cavity walls. In that case, the heat-conducting moisture will cause the insulation to lose its R-value. Mold and rot can also set in over time.

In general, vapor barriers are needed in areas with cold or mixed climates. Some insulation has facing already built-in, so check which type you have.

Check with local building codes and consult an expert while buying your insulation to determine if it’s needed in your home and area. When installing, be sure to seal any openings where air could leak.

Vapor barriers are somewhat controversial because anything that can keep moisture from seeping into a structure can also keep it from seeping out, leading to mold and mildew growth.

There may already be a vapor barrier between the sheathing and the siding. Some regulations require a vapor barrier inside the insulation in living spaces, and some don’t. You may want to check with the local building authority, but it’s probably just a matter of choice since it’s a garage.

The facing-on-faced insulation will form a vapor barrier. Whenever you’re insulating with faced insulation, the faced side goes toward the structure’s climate-controlled part, toward the inside of the garage.

  • It is best for interior and exterior walls in cold or humid climates, especially for homes with masonry or wood walls.
  • House wraps and kraft-faced insulation are examples of vapor barriers that help control the moisture amount that passes through the insulation.
  • Most used when framing the exterior walls of a house.
  • Installed after insulation.
  • DIY-friendly.
  • Not measured in R-values.

Do I Need to Heat My Insulated Garage?

Depending on where you live and how cold it gets, you’ll also want to use a heating source for the room. Insulation helps to contain the temperature, whether hot or cold and prevent it from escaping through the walls and ceiling.

Read all about garage heaters here and garage coolers here.

How Much It Cost to Insulate a Garage?

The garage insulation cost will vary based on geographic location, the material selected, and the space’s overall size.

Garage insulation costs vary based on the size of the space and the insulation you purchase. Estimated costs about 50 cents to $1.25 per square foot to insulate a garage. This means insulating a two-car garage would cost about $300 – $900 at least. (source homeadvisor.com)

Garage insulation: 1,400 sq.ft.

ItemUnit Costsq.ftTotal Cost
R13-19 insulation$0.73-$0.95 per sq.ft1400$1,022-$1,330
Labor$0.75-$1.00 per sq.ft1400$1,050-$1,400
Total$1.48-$1.95 per sq.ft1400$2,072-$2,730
(source homeadvisor.com)

Insulation Cost Per Square Foot

The following table shows the cost per board foot, which is 1 square foot by 1 inch thick. So, 1 square foot that is 6 inches thick would be 6 board feet. For your price range, simply multiply the prices listed below by the thickness you need. Each inch of insulation provides between a 3 and an 8 R-value. R-value rates how well the material insulates, the higher the value, the better the insulation. (source homeadvisor.com)

TypeMaterial Price Per Board Foot
Batting$0.30 – $1.50
Blown-in$1 – $2
Spray Foam$0.50 – $2
Radiant$0.20 – $1
Rigid$0.25 – $1
(source homeadvisor.com)

Spray Foam

Spray foam insulation costs $0.50 to $2 per board foot depending on if you choose to seal leaks and gaps inside existing walls. This insulation is the perfect solution for those who are looking for a relatively inexpensive way to fix a larger problem while increasing their home’s R-value. When done properly, spray foam can save you $500 or more a year in energy costs. (source homeadvisor.com)

  • Open-cell spray foam is generally $0.35$0.55 per board foot
  • Closed-cell spray foam is generally $1$2 per board foot

Blown-In Insulation

Blown-in insulation is perfect for the weekend warrior looking to get the job done cheaply.

Blown-in insulation costs $1,000 to $2,100 on average. Typically installed in attics, loose-fill insulation is also sometimes used to backfill wall cavities. Made from white cellulose, you can find reclaimed and recycled varieties. For DIY projects, you can purchase bags of it at a home improvement store and rent a blower for under $100 a day. Total DIY costs run $500 or less. (source homeadvisor.com)

Pre-installation prices for the most common types of blown-in insulation are $0.83 per square foot for Cellulose and $0.91 per square foot for Fiberglass. Therefore, 1,200 square feet of Cellulose insulation costs between $874 – $1,127, while Fiberglass costs between $950 – $1,244. (source homeguide.com)

Insulation TypeCost Per Square Foot
Cellulose$0.83
Fiberglass$0.91
Mineral Wool$1.02
Wool Fiber$5.44
(source homeguide.com)

Average costs of blown-in insulation for a 1,200 square foot area with an R-38–R-49: The R-value of an insulation material dictates how good the level of insulation is in the home. The US Department of Energy recommends an R-value of R-38 in most southern climates and R-49 in northern climates. (source homeguide.com)

Insulation TypeAverage Total Cost
Cellulose$874 – $1,127
Fiberglass$950 – $1,244
Mineral Wool$1,064 – $1,372
Wool Fiber$5,700 – $7,350
(source homeguide.com)

Fiberglass Batts

Fiberglass batt insulation costs $1,000 to $2,400. The average cost per square foot is between $0.30 to $1.50. So, for a 500-square-foot area, your estimate will vary between $150 to $700 if you do it yourself. For a professional job, add $200 to $500 for labor, and you’re looking at around $350 to $1,000 for 6 hours of work. When installed tightly and securely, fiberglass batts improve energy efficiency by 25 to 30% (source homeadvisor.com)

Reflective or Radiant Barrier

Radiant barrier insulation costs $700 to $2,900 on average. Materials alone run $0.25 to $1 per square foot, depending on the thickness and brand. To cover a typical 500-square-foot attic, you’ll likely spend $125 to $500, with double-sided barriers being slightly more expensive. To pay for a professional installation, add $575 to $750 to that cost. (source homeadvisor.com)

Roof Insulation

Roofs need to be sealed before insulation, which means seeking out and filling gaps, closing soffit vents, and so on. Water, after time, degrades insulation, rendering it useless. An insulated and sealed roof leads to a warmer attic in winter and a cooler attic in summer. Look to spend about $1,500 to pay for a professional job or a bit more for radiant or reflective barriers. (source homeadvisor.com)

Insulating Garage Doors

If you have an attached garage or simply want to make your garage warmer, insulating the door with foam kits is simple and only takes a few hours to complete. Depending on if you opt for batts, foam boards, or reflective insulation, you’ll pay about $200 for a 9′ door. (source homeadvisor.com)

Drywall

The average cost to install drywall is between $1.60 and $2.35 per square foot. For a typical 12′ x 12‘ room with a wall height of 8′, the price averages around $815 for just the walls, or a total of $903 if including the ceiling drywall. (source homeadvisor.com)

How Can I Insulate My Garage Cheaply?

A combination of blown-in cellulose in the attic and fiberglass batts in the wall stud cavities can be the cheapest way to go—if you do the insulating yourself. Fiberglass batts run between $0.64 to $1.20 per square foot, depending on the brand. Blown-in cellulose insulation to insulate a 1,000 square foot attic would cost approximately $560

Generally, the added insulation cost pays for itself through energy savings in less than a year or two.

Should I Insulate My Garage Floor?

Garage floors are often notably cold during winter months, so installing a layer of insulation could make the space nicer to work. You could use an insulation board or install a floor heating system.

Consider an epoxy floor also. Which works great with floor heating.

Consider installing a radiant floor heating system during the installation of the new garage floor. Installing a radiant floor system is not a DIY project—you’ll need to hire a plumber specializing in installing this type of floor heating system.

Expect to pay $5 to $9 per square foot to have the system installed, plus the boiler’s cost. But the resulting system is ideal for heating the garage workshop: It effectively warms the space.

How Long Does Insulation Last?

Insulation can last for many years, but moisture will reduce its useful life. When insulation gets wet (both fiberglass and cellulose), it packs down. It loses its loft, and when that happens, it also loses some of its thermal value.

What Is the Most Energy Efficient Insulation?

If you’re remodeling an existing home, spray foam is probably the best option for maximum energy efficiency.

Loose-fill cellulose or fiberglass can also be sprayed into existing structures.

So when it comes time to add or improve insulation in your house, look for the one that has the most appropriate R-value that works best for your home’s needs. This will depend on your home’s age, the structure itself, and where your house is located.

How Can I Keep My Garage Warm Without Insulation?

With different kinds of heaters, But you will be wasting money without insulation. 

Things to Consider

  • The most economical time to install insulation is during construction.
  • The higher the R-value, the better the thermal performance.
  • Insulation can help with weatherproofing and eliminate moisture problems such as condensation; some insulation types also have soundproofing qualities.
  • Some types of insulation require the use of masks and protective clothing.
  • Roofs and ceilings work in conjunction when it comes to insulation.
  • Adding insulation to existing buildings can significantly increase comfort and reduce energy costs.
  • Unfinished walls, thin metal doors, and concrete floors make the garage a chilly place to hang out.
  • Address any moisture problem before insulating since water from a leaky roof or window will damage insulation.
  • Seal all gaps around doors and windows to keep drafts out. If you take the time to insulate your garage—do it right—block the drafts while you’re at it.
  • Insulate water heaters to prevent costly energy loss. Look for insulating pre-cut jackets or blankets with an insulating value of at least R-8. Adding insulation to your water heater can reduce standby heat losses by 25- to 45-percent. This will save you around 5- to 10-percent in water heating costs.
  • Wrap hot water pipes with tubular insulation to prevent freezing and help keep water hot. Use quality pipe insulation wrap. Insulating your hot water pipes reduces heat loss. It can raise water temperature by 2- to 4-degrees Fahrenheit vs. non-insulated pipes, so you can use a lower temperature setting.
  • Insulated heating and air conditioning vent ducts operate more efficiently and vibrate less, reducing noise. Properly insulating air ducts located in unconditioned spaces such as attics, crawl spaces, garages, or unfinished basements can help improve your home’s energy efficiency.
  • Decide on the type of insulation to use. The home insulation types will have different units. For example, loose-fill insulation is calculated based on depth. In contrast, blanket insulation is based on the number of batts or rolls you need.
  • Calculate the additional insulation needed. Measure the depth of your current insulation. R-38 is the industry standard, and the minimum thickness for R-38 is 12-inches. If your existing insulation is only 5-inches deep, you’ll need to add seven inches of insulation to achieve the 12-inch R-38 rating.

The walls that are shared with the house should obviously be insulated to their maximum value.

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