Insulate Your Attic for Winter NOW!

Insulate Your Attic for Winter NOW!
Look at all that insulation!

That little nightly nip in the fall air should be reminding you that NOW is the time to insulate your attic for winter. Why? Well, first off, this is best time of year to do it because the weather tends to be cooler and drier. Having spent lots of quality time insulating attics, I can assert that staying cool, dry, and comfortable makes the whole adventure go much more smoothly and easily. The other reason is equally important: winter’s coming! So, if you want to make your home more comfortable and reduce your energy costs more (and who doesn’t after last year’s deep freeze), you should insulate your attic for winter NOW!

But before you get started, there’s one important thing you need to do first that can add even more to your savings: air sealing.

Insulate Your Attic for Winter NOW!
Proper air sealing on a can light in your ceiling

Controlling the Flow
Air sealing your attic properly stops the stack effect and reduces heat loss. The stack effect occurs when warmed air finds a way to flow into your attic. As it enters your attic, it pulls in cold air from somewhere lower in your home, such as drafts around doors or windows. By air sealing your attic, you can reduce the stack effect, and keep more warm air inside your home.

The way to do this is to use caulk to seal around light fixture electrical boxes in your attic. Sealing and insulating can lights (or recessed light fixtures) and soffits (such as those in bathrooms and kitchens) is equally important, but the job can be tricky. Prior to 2004, most can lights were rated as non-insulation contact (IC) rated which meant that insulation should be kept away from these due to the risk of fire from hot incandescent bulbs. How hot? The surface temperature of a 20 watt halogen bulb can reach 165°F, higher wattage halogens can hit 1200°F.

You can replace non-IC fixtures with “insulated-can, air-tight” (ICAT) fixtures. Not only do these keep warm air in your home but they also keep out moist, humid air in the summertime. However, since LED bulbs are much, much cooler it is possible to use those bulbs and enclose the non-IC fixture with a rigid styrofoam box.

Insulate Your Attic for Winter NOW!
Yup, even experienced attic insulators need to update old work.

Also remember to seal the holes where wires or plumbing enter your attic. Even if it is buried in insulation, the air finds a way through. In the photo to the left, you can see how air flowing through the wire-hole has blown the brown cellulose insulation into the side of the yellow fiberglass insulation. Also remember to seal where the chimney enters the attic. In older homes, these gaps can be several inches wide.

Thermal Security Blanket
While air sealing controls air flow, insulation actually reduces the transfer of heat energy (conduction) from inside your home through the building materials and into your attic. The ability for different materials to resist thermal transfer is rated in “R” values. For example, the R value for sheet rock is 0.45 for 1⁄2-inch thickness, a standard 4″ concrete block is R-1.11. Most homes are under insulated having only 3 to 6 inches of cellusoe or fiberglass insulation in their attics. That’s about R-11 to R-25.

Depending on where you live, the US Department of Energy recommends having between 8″ to 16″ (R30 to R60). Why so much? Insulation not only keeps the warm air inside during the winter but also keeps the hot air outside during the summer. By having a thick blanket of insulation in your attic, you can save money all year.

Insulate Your Attic for Winter NOW!
You can see the 3 on that tape measure, so that home really needs new insulation!

So what’s the right insulation for your home? Different kinds of insulation have different insulation values, installation methods, and different costs. Affordable cellulose insulation can be blown into place with special equipment —but it is very dusty. Fiberglass comes in inexpensive rolls or batts and can be easily put in place — but these need to be packed closely together and 2nd layers need to be placed perpendicular to the first to be more effective. Closed cell spray foam has the highest R value per inch, but it is expensive and requires special clothing.

Whichever insulation type you choose, keep in mind these tips:

  • Air seal your attic FIRST.
  • Prevent eave soffit vents from becoming blocked by insulation with rafter vents.Put these in BEFORE you start insulating. Retrofitting these is no picnic.
  • DO NOT put craft-faced insulation over an existing layer. Craft-faced insulation has a paper vapor barrier facing that could trap water condensation in the insulation and cause water damage and mold.
  • Know your attic’s layout in advance and work out how you will get the right level of insulation into place.
  • Buy your insulation a day or two in advance and store it in a dry place.
  • Choose a cool day and start early. Take water breaks and avoid getting overheated.
  • A 1″ x 12″ by 24″ board is your best friend in a tight spot. It will save your knees and probably keep you from falling through the ceiling.
  • It’s a dirty job. Wear long sleeves and pants, gloves, safety glasses, and especially a breather mask for protection against dust.
  • Keep insulation fluffy. Start work at the far end, work backwards towards the door to avoid insulation you’ve already put down.
  • Insulate and weather strip the attic doorway. You want this to seal as snug as possible.

The great thing about insulating is that you don’t have to get it all done at once. You can add insulation to your target thickness in stages, you can add to your attic in sections. The most important thing is that you’ll notice energy savings right away. And that ought to take the chill off of your winter.


Vernon Trollinger is a writer with a background in home improvement, electronics, fiction writing, and archaeology. He now writes about green energy technology, home energy efficiency, the natural gas industry, and the electrical grid.

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