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Written by Miranda Huey   
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Tuesday, 10 December 2013

Insulate Your Home!

No matter what the season, it's always a good time to insulate your home. According to the U.S. Department of Energy, most homes are not properly insulated if at all.1 So why should you insulate your home?

Benefits for the environment: An easy way to help the environment is through energy conservation. Generally, the less electricity you use, the less carbon emissions are released into the atmosphere.2

Benefits for your comfort: Whether it's winter or summer, you want your home to retain as much heat or cool air, respectively, as possible, so you can comfortably stay at a nice temperature without having to blast your heater or air conditioner. When you insulate your home, you can do just that.

Benefits for your wallet: Saving energy equates to savings on your electricity bill. Why waste money heating or cooling a house that constantly leaks the heat or cool air back in or out of the house? In fact, Energy Star estimates that you can save up to 20% on your heating and cooling costs just by sealing and insulating your home.3

Seal and Insulate Your Home 4

Cost: Medium to High
If you do it yourself, insulating your home can cost you around $100-$500.5 Although it might sound like a lot, in the long run, you can easily save this much money just through savings on your electricity bill.

Time and Effort: Medium Insulating your home only takes around a day or two of shopping for the materials and using them to insulate your home.6 If you have a weekend to spare, that's a perfect time to consider insulating your home.


  • Work gloves
  • Goggles
  • Utility knife
  • Dust mask
  • Staple gun
  • Straight edge
  • Flashlight or work light
  • Plywood board (if your attic has loose fill insulation)
  • Unfaced insulation
  • Faced insulation
  • Reflective foil or rigid foam board
  • Expanding foam
  • Caulk (normal and high-temperature resistance)
  • Aluminum flashing
  • Mastic or foil tape
  • Zip ties
  • Self-adhesive weatherstrip


Add insulation: The best place to add insulation is in the attic, since it is the area that provides the most savings-potential.7 However, you can also use these same steps and apply them in basements, garages, and crawlspaces.8
  1. Look out for vermiculite insulation before working in the attic: Some vermiculite insulation contains asbestos, a health hazard. If your attic's insulation is lightweight, pea-size, flaky, and grey, don't disturb the insulation until you've had it tested by a lab.9
  2. Figure out whether you need to add insulation: If your floor joists are covered or at a lower level than your insulation you have enough otherwise you should add more.10

    Enough Insulation11 Lacking Insulation12
    Enough Insulation Not Enough

  3. Figure out the level of insulation you need: Most attics should be insulated to around R-38, but attics in Northern climates should be insulated for up to R-49. If you are installing at more than R-38, you should install the insulation in two layers. The first layer should be faced insulation with the vapor barrier down, and the second should be unfaced (without a vapor barrier) and placed perpendicular to the first layer.
  4. Measure the space between joists and between rafters: Using this measure, you can determine what size insulation to buy. Also, measure the width and length of your attic to help you figure out how much insulation to buy.
  5. Count the number of soffit vents: Soffit vents are the vents on the outside of your house, under the sides of the roof, which allow outside air to ventilate inside into your attic. Since you will be installing one rafter vent for every soffit vent, count how many soffit vents in your attic need rafter vents.
  6. Put on your work gloves, goggles, and dust mask: The attic has a lot of dust, nails, and particles that could easily hurt you while you are shuffling about in the attic. With these precautions, you can be protected from some of these dangers, but still be sure to be on the lookout for any potential danger. Be sure not to step on any ceiling drywall or insulation.
  7. Loose fill insulation: If you already have loose fill insulation, it may be a good idea to just add more loose fill insulation by renting a blower machine from the nearest home improvement store. Lay down a polyethylene vapor barrier between the floor joists and rafters and staple them into place.
  8. Roll insulation: Just roll the insulation between floor joists and rafters. To hold it in place, staple the insulation every two inches. In order to cut the insulation, keep the faced side up, press down on the insulation, and cut with your utility knife.
  9. Install rafter vents: Place rafter vents right in between where the ceiling meets the floor. Staple them directly onto the roof decking and partially cover them again with insulation. These will help to ensure that the attic has proper ventilation.13
Seal air leaks: Air leaks are hidden everywhere, but looking in the right places can lead you right to the biggest leaks. Here's where to go:
  • In the attic:
    • Behind Kneewalls: If you have a finished attic, seal behind the kneewalls, or the areas between the walls and the sides of the roof. In order to insulate there, cut a 24-inch long piece of insulation and push it to the bottom of a 13-gallon plastic garbage bag. Fold the bag and stuff it into any open joist spaces under the interior wall. After you're done, make sure it gets covered again by the floor insulation.
    • Wiring holes: Fill any wiring holes with expanding foam. If there are any electrical junction boxes, caulk around the boxes and fill any holes with caulk.
    • Open Soffitt (Dropped Ceiling): A soffitt is the gap left behind in the attic by a dropped ceiling. Reach inside the soffitt and remove any insulation left in there. Cut some reflective foil or rigid foam board a few inches longer than the opening, cover the opening with this, and caulk the edges. If necessary, staple or nail the foil or board in place.
    • Under darkened insulation: Dark or water-stained insulation is a sign of a small air leak. If you look under the insulation, you might find dust trails or stains leading to a source of an air leak. Just seal the areas with caulk or expanding foam. Don't worry about the dirty insulation. Even though it's dark or stained, it still works, so you can just push the insulation back in place once you're done sealing any leak.
  • In the basement: Often, outside air can leak indoors through the gap between a cement foundation and a wood frame, otherwise known as the “rim joist”. Use caulk or expanding spray foam to seal along the gap between the foundation and the sill plate and at the bottom and top of each rim joist on each end of the house. 14
  • Windows and doors: The easiest to seal are windows and doors around the house. Use caulk around the outermost frame of windows and doors to insulate against any leaks from outside.15
Seal pipes, air ducts, and attic hatches: Some things are a little bit more complicated to seal, but are major sources of drafts. Here's how to tackle these problem areas:
  • Plumbing pipes: Plumbing pipes can be found in the attic or the basement. If the space around the pipes is more than 3 inches, stuff the space with some fiberglass insulation. After that, use expanding foam to fill in the space around the pipe.
  • Furnace flues, water heater pipes, or chimney pipes: Look for pipes that are made out of a metal other than cast iron,16 and these are probably furnace, heating, or chimney pipes. Be careful, since these can get very hot. Create a bead of high-temperature caulk 1-2 inches around the flues. If the flue or pipe is round, use two half circles overlapping by around 3 inches on each side. Seal the bottom of this again with more high temperature caulk. Create another layer of aluminum flashing at 3 more inches around the first layer, but staple it down and bend the top inward to form a horizontal cover. After this, you can install installation against the side of the second layer.
  • Air Ducts: Sealing and insulating the ducts can increase the efficiency of a heating and cooling system by 20%. To find the leaks, just turn on the heating and cooling system fan and feel for any leaks. Using mastic or foil tape, seal any joints. Seal any spaces around a duct in an attic floor with foam, then add insulation around the ducts and use zip ties to hold it in place.17
  • Attic Hatch: Attic hatches are some of the biggest sources of air leaks.18 To insulate it, add weatherstripping to the door to seal the access hatch. Then, cut 1” by 3” wooden boards that fit around the perimeter of the access hatch. This is the hatch's new stop. Nail these onto the perimeter of the access hatch. Weatherstrip the top edge of this new perimeter. Then, install a hook and eye latch to compress the weatherstrip between the hatch and the wooden stop.19
When to hire a contractor: Sometimes, while trying to insulate your home, you can encounter either a much bigger problem or another problem entirely. These are the situations when you should probably hire a contractor:
  • Diagram of an Ice Dam21
    Ice damming: If your house usually has ice dams in the winter, it can mean your attic has serious air leaks that should be fixed by a contractor.20 What are ice dams? Ice dams are a build-up of ice up on roof overhangs that seep under shingles and damages the roof, walls, and attic. It can happen when snow that falls onto roof melts because of the rising heat from your attic, but then refreezes at roof overhangs, causing ice to accumulate and back up within your roof.22
  • Wet or damp insulation: If your insulation is wet or damp, you probably have a leaky roof, and not just an insulation problem.
  • Moldy or rotten attic rafters or floor joists: Rafters, the beams which support a roof,23 and floor joists, the beams used to support floors,24 can get moldy or rotten, which generally means that the attic has moisture problems, which may not be able to be corrected just through standard sealing and insulation.
  • Kitchen, bathroom, or dryer vents leading to attic instead of outdoors: These vents can exhaust moist air into the attic, causing a buildup of moisture to mold your rafters or floor joists. You should probably hire a contractor to move the moisture outdoors.
  • Little or no attic ventilation: Although a lack of outdoor ventilation may seem like even better insulation than having a ventilated attic, it actually can cause problems. In the winter, an attic that's too hot relative to outdoor temperatures can create ice dams. In the summer, this ventilation moves hot air out of the attic, which protects roof shingles and gets rid of moisture. 25
  • Knob and tube wiring: If you have a house since before 1930, you may want a professional, since these can become a fire hazard when insulation is placed next to them.
  • Recessed “can” lights: If you see that your recessed “can” lights are unsealed and not insulated, you probably shouldn't try to insulate them yourself, since a special technique is used to insulate them properly.26 Recessed lights are used to highlight certain areas or pieces in a room and they maintain the ceiling line of the room, often opening up the room and making it seem larger.
Good luck with your insulating!

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Last Updated ( Tuesday, 10 December 2013 )