Smart moves for a warmer home

How to add insulation and remove the chill

How do you know if your home needs more insulation?

Maybe your bedroom is so icy you can hardly stand to get out of bed, or your heating bills seem awfully high when your home isn’t terribly warm.

Perhaps you’ve already added energy-efficient windows, replaced your front door and installed a new furnace, but you still have to wear a coat indoors.

Adding insulation to your attic or walls, especially if your home is older, will help maintain a more comfortable temperature, lower energy bills and reduce sound transmission.

While you’re at it, sealing your home’s leaks and improving its ventilation will give you more bang for your buck.

And you might even be able to do the work yourself.

Our 12 smart moves will show you how to add some warmth to your home.

Get a home energy audit

Getting a home energy audit rather than hiring an insulation pro as your first step means you’ll get an unbiased opinion of the work you need to do.

A home energy auditor should do the following:

Ask what problems you’re experiencing.

  • Review your utility bills and ask about your energy needs.
  • Examine your home’s existing insulation by looking in the attic, basement, crawl space and behind electrical outlets to check for insulation in the exterior walls.
  • Use a tool called a calibrated blower door to locate and quantify air leaks.
  • Use infrared scanning to locate warm and cool spots.

Your gas or electric company may offer free home energy audits. If not, check the Residential Energy Services Network’s online directory.

Expect to pay $300 to $500 for this service.

While that may sound expensive, the rest of your investment in insulating your home may not pay off like you expect if you don’t know where your home’s weak spots lie.

You can check air leaks yourself

If money is tight, skip the audit and check for energy-wasting air leaks yourself.

You probably know that air can leak around windows, doors and outside walls. But the Department of Energy says the following also are major sources of air leakage:

  • Dropped ceilings
  • Kitchen soffits
  • Ductwork and wall openings for plumbing
  • Attic access points
  • Recessed lights
  • Holes in mechanical room closets
  • Wire entry points at the top of walls
  • Attic walls, called knee walls, that support rafters
  • Around the bathtub drain
  • Around plumbing and wiring entry points through the floor
  • Band joists of two-story homes
  • Through exterior walls

If you can see light coming through any of these places, you have an obvious leak.

To detect subtle leaks, close all windows and doors and turn off all fans and the furnace. Light a stick of incense, hold it in front of potential leaks, and see if the smoke changes direction. If it does, air is being blown into or sucked out of your home, and you have a leak. A damp hand will also help you detect drafts.

Seal those air leaks

Before adding insulation, seal all air leaks. You can do this step yourself or have an insulation contractor do it.

There are a number of materials for sealing air leaks. The material of choice depends on the leak’s location and size.

Caulk is best for sealing leaks of less than a half inch. It can be used to seal outlets, light fixtures, baseboards and wall openings for plumbing.

Spray foam can help seal larger gaps, such as gaps between baseboards and floors, but shouldn’t be used near heat sources because it is flammable.

Foam gaskets can be used behind outlet covers and switchplates.

Rope caulk is best for sealing doors and windows. It’s sometimes used along with regular caulk.

Weatherstripping also helps seal windows, doors and attic access doors/panels.

Sheet metal plus high-temperature caulk is used to seal flues, vents and chimneys.

Mastic seals gaps in the ducts that carry air throughout your home.

Properly ventilate your home

While it’s important to seal your home against air leaks, the goal is not to have your home completely sealed off from the outside. But you want to choose how much and where air flows in and out.

Proper ventilation provides a controlled flow of air through your home. It mitigates indoor air pollution, prevents moisture problems, removes odors, and helps your home cool and heat effectively.

Your kitchen should have an exhaust fan that draws grease and smoke outside.

Bathrooms also need exhaust fans that vent outdoors to get rid of moisture and odors. Humidity can cause rot, mold and peeling paint.

Attics and crawl spaces should have vents that pull air through, taking heat and moisture out of your home.

In addition to vents in the eaves of your roof, ridge vents, which run along the peak of your roof, also help remove unwanted heat and humidity from the attic and can extend roof life.

Vents should be sealed against air leaks and not blocked by insulation.

Learn about R-value

Insulation’s R-value lets you know how resistant it is to heat flow. The higher the R-value, the higher the resistance.

Different parts of your home require different R-values of insulation. Attics and cathedral ceilings require the most, while wall cavities require the least.

How much insulation you need depends on how old your home is and your climate.

The older your home, the more likely it needs more insulation. State building codes didn’t require insulation in new homes until the late 1970s.

The amount of insulation you need in your attic ranges from R25 to R60 depending on whether you live at the southern tip of Florida or the northern tip of Maine and whether you have any existing insulation.

Wall cavities need an R-value of 13 to 21.

R-values are cumulative, so if you have existing insulation with an R-value of 5, you can add insulation with an R-value of 25 to get an R-value of 30.

Check the North American Insulation Manufacturers Association website ( to see how much insulation your home needs.

Pick from traditional insulation types

There are four traditional types of insulation.

  • Fiberglass: It is inexpensive, easy to install, suitable for DIYers and resistant to moisture and fire. It is the least expensive option.
  • Mineral fiber insulation: Made from slag wool and rock wool, it is similar to fiberglass but costs more. Because of its fire resistance, it is better for use around chimneys.
  • Cellulose: Made from chemically treated recycled paper, it is good for irregular spaces like unfinished attic floors. But it isn’t fire resistant, you can’t install it yourself, rodents can nest in it, moisture will ruin it and the chemicals that are added to it may hurt indoor air quality.
  • Expanded cork: Sustainably harvested from mature oak trees, it is more effective than fiberglass, can reduce sound by up to 50 decibels, can last 50 to 60 years, and is moisture, fire and insect resistant.

Cost varies widely based on the material you choose, how much of it you need and where you live, but we've seen estimates for installed fiberglass insulation of between 50 cents and $1 per square foot. Expect to pay more for the other types of insulation.

Or consider newer insulation types

Foam insulation has only been in use since the 1970s. It comes in two types: open cell/semi-rigid and closed cell/rigid.

Either type can be applied as a spray foam, which can be used to insulate finished walls or sprayed into the attic ceiling. The foam is sprayed in as a liquid, which quickly expands to fill the cavities. A drawback is that spray foams release potentially harmful chemicals into the air during application.

Spray foam must be professionally installed, because it requires special handling and equipment, and can be harmful if oversprayed, says Marcelo Kohan, principal architect of Delargent Design Architecture in Merrick, NY.

Both are fairly expensive, but can insulate well in small spaces like wall cavities.

Recycled denim is used in some green building applications. Its properties are similar to those of fiberglass, but it isn’t easy to find.

Add insulation to exterior walls

Uninsulated or underinsulated exterior walls, including walls between finished interiors and unfinished areas like garages, are a major source of heat loss in winter and heat exposure in summer.

An uninsulated wall’s R-value is just 5, while a well-insulated one can have an R-value of 22.

But you can solve this problem without ripping off the drywall and creating a huge mess.

Your first option is to add insulation from the exterior at the same time that you redo your home’s siding.

You can also add insulation from the inside.

In a wood-framed house, the basic process is to open the wall cavity by using a stud finder, then cut small holes between the studs through which insulation can be blown, says Gary Wagner, CEO of Green Distribution, a sustainable building products distributor in Boca Raton, Fla.

You’ll need to rent an insulation blower machine to fill the wall cavities. Then you have to reseal the holes that you cut into the walls.

It’s a patching job, not a wholesale demolition and reconstruction of your walls.

Beware of asbestos

Many older homes have insulation that contains asbestos.

When asbestos-containing materials are disturbed, tiny particles become airborne, where you can inhale them and potentially develop a nasty, life-threatening lung disease 10 to 40 years later.

Vermiculite, a popular insulation material in the 20th century, is particularly likely to contain asbestos. It looks like mica flakes and might have been poured between your ceiling joists as attic insulation.

A good contractor should be able to tell if you have potentially hazardous insulation, and an asbestos inspector should be called in to check it, says Marcelo Kohan, principal architect of Delargent Design Architecture in Merrick, N.Y.

The best way to deal with insulation that might contain asbestos is to leave it alone, but if you must remove it, you’ll need to hire an asbestos remediation company.

You can add more insulation without removing asbestos-containing insulation, but it has to be done in a way that doesn’t disturb the potentially hazardous material.

For $25 to $150, you can have an insulation sample lab-tested for harmful asbestos. A complete remediation for your home could cost $2,000 to $10,000.

Hire a professional

Neighbors, friends, your city planning office and local utility companies are all potential sources of recommendations for insulation contractors. Don’t hire a general contractor, who may not have enough specialized knowledge.

Check the company’s license, insurance and certifications, and contact references.

Then get detailed, written estimates from at least three companies.

Estimates should state what material will be used, its R-value and its cost, and the hourly fee for labor and an estimated labor total.

Insulation contractors must show you fact sheets for the insulation they sell and give you a signed and dated contract or receipt for the materials.

For batt or board insulation, the receipt should show the insulation’s coverage area, thickness and R-value, states the North American Insulation Manufacturers Association’s website. For loose-fill insulation, it should show coverage area, installed thickness, minimum settled thickness, R-value and number of bags used.

Also, contact your local building department to make sure the scope of work will meet local codes for required minimum R-values.

Do it yourself

Installing insulation can be a DIY project, but here are the caveats.

You’ll need to understand which types of insulation are best for your specific needs in terms of effectiveness and fire resistance.

Use the wrong type of insulation in your attic and an unattended light bulb that’s too close could set it on fire. Also, the vapor retarders that protect against moisture levels may be flammable even if the insulation they cover isn’t.

Improperly installed insulation can lose as much as 50% of its effectiveness. Consult the North American Insulation Manufacturers Association’s chart showing what R-value each area of your home needs.

Also, pipes that aren’t insulated can freeze, and blocking vents with insulation won’t allow air to circulate properly throughout your home, which can create moisture and indoor air quality problems.

Estimate your return on investment

A well-done insulation job can reduce your heating and cooling bills by 20%, according to the Environmental Protection Agency.

To calculate how long it will take your insulation project to pay off, you’ll need to estimate the part of your utility bills attributable to heating and cooling for the last year, then calculate 20% of that total. So if you spend $2,000 a year on heating and cooling, your insulation project could save you $400 per year.

If you spend $1,600 to upgrade your home’s insulation, your investment will start to pay off after four years ($1,600 divided by $400).

A well-insulated home can also pay off if you decide to sell one day because a home that is more comfortable and has lower energy bills will be more attractive to potential buyers.

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