Save on Pinterest

25 Things You Need to Know About Insulation

We all know insulation is important to having a comfortable and energy-efficient home. Check out these 25 things to consider when thinking about adding insulation to your house.

1 / 25

Upgrade Your Insulation

If you're planning to buy an insulated door because you want to save energy or keep your garage warm, it's worth spending about 15 to 20 percent extra to upgrade from extruded polystyrene to polyurethane insulation. The insulating effectiveness of a garage door is its R-value. The larger the number, the better it insulates. According to Clopay, upgrading from 2-in. polystyrene to its Intellicore (polyurethane) raises the insulating value from R-9 toR-18. That's a lot of bang for the buck.
2 / 25
Avoid Paper-Faced Insulation Where PossibleFamily Handyman

Avoid Paper-Faced Insulation Where Possible

Don't buy paper-faced insulation for standard wall insulating jobs. The paper facing makes cutting the batts difficult. And it's hard to create a tight vapor retarder with paper-faced batts.

3 / 25
Missing Insulation Feeds MoldFamily Handyman

Missing Insulation Feeds Mold

Warm air seeks gaps in the insulation, and when it hits colder surfaces as it flows out of or into the house, water condenses—which then feeds mold. These spots often occur on outside walls near floors or windows, at corners and around outlets and lights. If the mold disappears after cleaning it and lowering indoor humidity with a dehumidifier or vent fan, just keep an eye on it. If it recurs, open the wall and fix the problem. Learn how to properly use expanding foam.

4 / 25
Add Attic Insulation

Add Attic Insulation

In most homes, but especially in older homes, adding insulation in the attic will cut heat loss. At a minimum, homes should have attic insulation between R-22 and R-49 (6 to 13 in. of loose fill or 7 to 19 in. of fiberglass batts). Check with the local building department to find the recommended level for your area, or visit

Stick your head through the attic access door and measure how much insulation you have. If your insulation is at or below the minimum, adding some will lower your heating bills. If you need to add more, go with loose-fill insulation rather than fiberglass batts even if you already have fiberglass. Loose fill is usually composed of cellulose or fiberglass and lets you cover joists and get into crevices. Pros charge about 70?? per sq. ft. to blow in 7 to 8 in. of insulation. You can rent a blower ($55 a day) and do the job yourself for less than half that cost, but it's a messy job and you have to watch your step so you don't go through the drywall 'floor' in the attic.

'Eighty percent of houses built before 1980 are underinsulated.' —Department of Energy.

5 / 25
Don't Spin the Bit In InsulationFamily Handyman

Don't Spin the Bit In Insulation

The best advice for fishing wires through insulation is “Avoid it if you can.” The potential is always there to damage the vapor barrier or bunch up insulation, leaving cold spots in the wall. If you must fish wires through exterior walls, the best tip is to avoid spinning the flex bit until you make solid contact with the wood you plan to drill through. If you drill too early, you'll end up creating a large insulation cotton candy cone, which will make retrieving your bit difficult, if not impossible. Plus: Check out 25 things you need to know about insulation.
6 / 25
Itch Remover

Itch Remover

A sticky lint roller pulls those nasty insulation fibers off your skin and clothes—and reduces itching later.

7 / 25
Insulate PipesFamily Handyman

Insulate Pipes

Condensation dripping from cold pipes can contribute to basement water problems. Cover cold water pipes with foam pipe insulation to stop condensation. The foam insulation is inexpensive and easy to cut with scissors.

8 / 25
Insulate WallsFamily Handyman

Insulate Walls

Insulate exterior walls to prevent condensation. In cold climates, wall insulation in the basement also saves energy and reduces your heating bill. But don't cover the walls with insulation if water is leaking in from outside; you'll just create a potential mold problem.
9 / 25
Seal the Rim JoistsFamily Handyman

Seal the Rim Joists

Uninsulated rim joists are huge energy losers. Now's the time to insulate and seal your rim joists. One option is to seal the rim joists with rigid insulation cut to fit. We recommend a minimum of 2-in.-thick extruded polystyrene, but check your local codes to see what's required. If you have a table saw, use it to cut strips equal to the depth of your joists. Then use a fine-tooth handsaw, utility knife or miter saw to cut the strips to length. Fill small gaps with caulk, and larger ones with expanding spray foam from a can.
10 / 25
How to Find the Gaps

How to Find the Gaps

Before you crawl into your attic, make a rough sketch of the floor plan and the ceiling below the attic. Sketch in the walls, the chimney, the main plumbing stack, ceiling electrical fixtures and lower sections of ceiling. They all have high leak potential, and your sketch will help you find them when you're in the attic.

To help generate actual leakage, place a box fan in a window so it blows air into the house. Then close all other windows and doors. Tape cardboard around the fan to eliminate large gaps. When you turn the fan on high, you'll slightly pressurize the house, just like an inflated balloon. Then when you're in the attic (with the hatch closed), you can confirm a leaky area by feeling the air coming through. You may even spot the insulation blowing in the breeze.

Another helpful sign is dirty insulation (photo above). Insulation fibers filter the household air as it passes, leaving a dirt stain that marks the leaky area.

11 / 25
Use Foam or Caulk for Small Gaps

Use Foam or Caulk for Small Gaps

It's best to keep your can of expanding foam and caulk gun handy and plug the obvious electrical cable holes and fixture boxes as you move around working on the bigger air leaks. Make sure you get to the plumbing vent, because the gap around it is usually large. Also look for the 2x4 top plates (framing) of interior walls and follow them, keeping a sharp eye out for electrical cable holes and dirty insulation, which would indicate a gap or long crack between drywall and a wood plate. Seal these with caulk.

Work carefully with expanding foam because it's super sticky and almost impossible to get off your clothes and skin. Wear disposable gloves when working with it.

12 / 25
Weatherstrip Hatches and DoorsFamily Handyman

Weatherstrip Hatches and Doors

After sealing the attic bypasses, push the insulation back into place with an old broom handle or a stick as you back out of the attic. Then finish up by sealing the access hatch with self-sticking foam weatherstrip. You may have to add new wood stops to provide a better surface for the weatherstrip and enough room for hook-and-eye fasteners. Position the screw eyes so that you slightly compress the weatherstrip when you latch the hatch. Use a similar procedure if you have a hinged door that leads to the attic.

13 / 25
Use Mold-Resistant Building MaterialsFamily Handyman

Use Mold-Resistant Building Materials

If you need to build or rebuild an area where moisture has been a problem, use materials that resist mold growth and aren't affected by water. Construct walls with pressure-treated wood and rigid insulation and cover the walls with paperless drywall, which has nothing for mold to feed on. Learn how to install cement board for ceramic tile.

14 / 25
Cut Around the Window With a Recip SawFamily Handyman

Cut Around the Window With a Recip Saw

Spray foam insulation does an excellent job of insulating around a window—and a surprisingly good job of keeping the window or door in place. Even if you remove all the fasteners holding in a window, you won't be able to pull the window out until you deal with the spray foam. So don't bother pulling the nails or screws out of an old window. Just run a recip saw between the window and the framing and cut the fasteners and the foam at the same time. You may want a buddy on the other side of the window to keep it from falling out when you're done cutting around it. With a long enough blade, you can even slice through the nailing flange at the same time. That's important if you're trying to save the siding around the opening. Learn how to prevent leaks with proper window installation.
15 / 25
Use a Leak Detector to Find Drafts

Use a Leak Detector to Find Drafts

If your home is drafty, use a thermal leak detector (several brands are available online). The battery-operated handheld tool uses infrared sensors to identify spots that are warmer or colder than the surrounding area, signifying an air leak or poor insulation.

Just point the Thermal Leak Detector at windows, walls and ceilings. When the detector finds a cold or warm spot, the LED light changes from green to red (for warm) or blue (for cold).

Of course, you'll still have to do some detective work to figure out what the problem actually is and how to fix it.

16 / 25
Seal Small Attic Holes With Foam and Caulk

Seal Small Attic Holes With Foam and Caulk

Hot air rises, so leaks in the ceiling are even worse than leaks in walls. And in many homes, this airflow through ceilings and into the attic is the No. 1 source of heat loss. You can check for leaks around ceiling light fixtures and the attic access door using an incense stick. But the only way to detect other leaks is to crawl up into the attic, pull back the insulation and look for them. Most leaks occur where chimneys and electrical and plumbing lines pass through the ceiling. Although the attic is a nasty place to work, plugging these leaks is a simple project—mostly caulking and foaming gaps.

17 / 25
Cut Fiberglass Batts to Exact WidthsFamily Handyman

Cut Fiberglass Batts to Exact Widths

It's easy to insulate your walls with fiberglass insulation (at least when they're open!), but the job still requires attention to detail to get the maximum benefit. Every gap and compressed batt leaves a path for heat or cold to escape.

Measure and cut the fiberglass batt for an exact fit. Add about 1/4 in. to the measurement to ensure a snug fit. Use a 4- to 6-in.-wide board or strip of plywood as a straightedge to guide your utility knife. Line up the edge of the board at the proper width, compress the insulation and cut it with a sharp utility knife. A scrap of plywood under the batt will protect finished floors and keep the blade from dulling on concrete.

18 / 25
Avoid StuffingFamily Handyman

Avoid Stuffing

Don't stuff full-width batts into spaces that are too narrow. Crumpling batts to fit narrow spaces creates uninsulated air pockets. And packed insulation has a lower R-value.

19 / 25
Notch Batts Around Electrical BoxesFamily Handyman

Notch Batts Around Electrical Boxes

Cut notches in batts to fit snuggly around electrical boxes. Airtight boxes have gaskets that seal against the drywall.

Put the batt in place, and use a scissors to snip around the box. Tuck the snipped-out plug of insulation behind the box. Don't wrap fiberglass batts around electrical boxes or stuff full batts behind them. That creates gaps and air convection routes around the box.

20 / 25
Split Batts Around Cables and PipesFamily Handyman

Split Batts Around Cables and Pipes

Split apart the batts to fit around wires and pipes to get the full value of the insulation. Fiberglass batts have a vertical weave that allow you to easily tear it open for insulating around electrical cables.

21 / 25
Clean Attic Venting or Invite Ice DamsFamily Handyman

Clean Attic Venting or Invite Ice Dams

Poor attic ventilation can cause ice dams in the winter months, increase cooling costs, create a home for mold and reduce the life of shingles during the dog days of summer.

Over time, the vents located in your soffits and on some gable-end wall vents get clogged with dust and debris and lose their effectiveness. Clean them with a leaf blower or compressed air. You could use a pressure washer, but stick to a couple quick passes because you don't want to saturate the attic insulation with water. Clean the vents every few years, unless you live near a lot of trees with floating seeds, which can clog vents in one season. For much more on preventing ice dams, check out this guide.

22 / 25
What's R-Value?Family Handyman

What's R-Value?

R-value is a measure of the resistance to heat flow, a way of indicating insulation's ability to stop heat from moving through it. The higher the number, the better. Insulation is labeled by total R-value. Two factors determine that number: the thickness of the insulation and the insulating ability of the material. The fiberglass batts shown here, for example, are all the same thickness but differ in R-value because of their different densities.

23 / 25
Plan AheadFamily Handyman

Plan Ahead

Even in a cosmetic remodel, there can be an opportunity to enhance the function or money-saving capability of your home. When ripping out an entire room, for instance, this may be the perfect time to add insulation to the walls, upgrade your electrical panel or add additional light or electrical fixtures. The key is to think ahead to how you will use the room, and take advantage of cosmetic updates to enhance the structure of your home.
24 / 25
Insulate Hot Water PipesFamily Handyman

Insulate Hot Water Pipes

Are your hot water pipes insulated? Remember, pipes (especially metal pipes) conduct heat, and your hot water can lose a lot of heat traveling through cold pipes, which means you'll have to let your faucet run longer before hot water comes out. Insulating pipes is an affordable solution to this problem, keeping heat contained within the pipes and shortening the time it takes for your water to run hot so you waste less.
25 / 25
Packaging Fragile ParcelsFamily Handyman

Packaging Fragile Parcels

If you're sending a fragile gift, protect it with expanding foam sealant. First, double-wrap the item in plastic bags, then cover the bottom of your box with 2 to 3 in. of foam. After about 45 minutes, when the foam has expanded and begun to harden, put the item in the box. Then line the box with a plastic bag large enough to cover the item and the sides of the box. Partially fill the box with foam, covering the gift but leaving a couple of inches for the foam to expand. Let the foam set overnight before handling the package. If the foam expands past the top of the box, just cut away the excess with a knife. A can of regular foam?not the 'minimal expanding' version?fills almost a cubic foot. If you're not familiar with expanding foam sealant, here are 17 ways to master this versatile product.

Newsletter Unit

CMU Unit

Subscribe & SAVE 1 Year Subscription
for only $10!