Insulating Your Attic for the Winter

Are you looking to improve your home's energy efficiency level going in to the winter? If the answer is yes, you've read my article "Seven Tips to Lowering Your Electric Bill," and you're still looking to do more, perhaps you should consider insulating your attic. Insulating your attic is an easy and reasonably inexpensive way to reduce your home heating bills.

There are two ways to insulate your attic. You can use either blown in or batt insulation. Blown in fiberglass or cellulose have been growing in popularity, but blown in insulation is really more practical in walls of existing homes than it is in accessible attic space.

Blown in insulation often offers a slight savings over fiberglass batts and rolls, but the savings is generally not great enough to justify the mess of the job. In addition to the mess involved in actually doing the blown in insulation job, blown in insulation in the attic can be messy afterwards as well. As air ventilates through the attic, it has a tendency to move some of the blown in insulation on top of your pull down attic stairs. This makes for a nice cellulose shower when you open your attic stairs. Blown in insulation can also be messy down the road should you choose to add any ceiling light fixtures to the top story of your home.

Fiberglass insulation batts and rolls, on the other hand, make for a much cleaner insulating job in the attic. Though this product does have some particles that will get into the air, because it is a solid product, it is much cleaner to work with in both the long and short term.

Before starting a job with fiberglass batts or rolls, there are a few tools that you will need to do the job. A disposable dust mask or respirator and a good pair of safety goggles are necessary to product your lungs and eyes from airborne dust and fiberglass particles. You should also wear gloves, long sleeves and pants to minimize itchiness. If the temperature does not permit long sleeves and pants, you can always wear a Tyvek suit over your shorts and tee shirt. Aside from safety equipment, the only other tool that you will need for this job is a standard utility knife.

So how much insulation is enough? That question is always up for debate, but as a general rule of thumb, if you can see your ceiling joists, you don't have enough insulation. In some areas, like upstate New York, many new homes are having insulation levels of R-49 or more put in the attic.

Since fiberglass insulation does not come available in an R-49, you may be wondering how to determine what combination of insulation you should use to meet an R-49 value. Generally speaking, you should use whatever size fits evenly with your ceiling joists, combined with an insulation that will make up the difference of the R-value. For example, if your ceiling joist is a 2x10, you would purchase an R-30, which is 9-1/2" thick, and an R-19 to lay on top of it.

When you purchase your insulation, the insulation that has thickness consistent with your ceiling joists should be faced while the other insulation should be unfaced. When you install this insulation, the faced insulation should be installed with the face down. This is because your vapor barrier should always directly border the heated portion of your home. The unfaced insulation will be installed on top. The top layer of insulation will be installed perpendicular to the bottom layer so that it completely covers your ceiling joists and provides maximum coverage.

Many do-it-yourselfers have questions about what is better: rolls or batts. Batts are precut pieces of insulation that are cut to common lengths such as the height of a wall or a number that divides evenly into a common floor size. Many professional insulators use batts for both floors and walls because by minimizing their cutting, they maximize their efficiency. Batts and rolls can both be used when insulating your attic, but if you have the opportunity to use rolls you can minimize the number of seems that you have which will help to prevent small gaps where hot air can escape.

When choosing the width of your insulation, the bottom layer must be the same width as the spacing of your ceiling joists. For instance, if your ceiling joists are 16" on center, your bottom layer of insulation should be 15" to 16" wide. The width of your top layer doesn't really matter, but it using 23" wide insulation on the top will be quicker to put down and will minimize your seams.

Here are some other basic tips for installing your fiberglass insulation. First, to cut the insulation, repeatedly score it with a utility knife and then tear it apart. Second, when seaming insulation, put it as close together as possible to prevent hot air from escaping. Place insulation baffles between the insulation and the roof decking to allow air to circulate and prevent moisture from getting trapped in the roof decking. Finally, if you have any areas where there are small gaps between ceiling joists, make sure you stuff them with insulation.

Another product that you may consider adding if you have pull down attic stairs is an Owens Corning attic stair cap. This is a shaped piece of foam insulation that goes over your attic stairs in order to prevent them from providing the point of least resistance for hot air.

Insulating your attic is a very basic and easy job. It is one of the few jobs in remodeling where the final cost is very close to the cost of your base product because there are very few add ons for this job. This is a job that a novice should reasonably be able to finish in a day. After that, you can start saving on your heating and cooling bills.