Many homeowners are unaware of the vital role their attic plays in the home. Not only can the attic keep the house at a comfortable temperature and prevent air leakage, but financial savings are very possible through a properly weatherized attic.
In an attic that has not been properly weatherized, warm air can easily leak out and let cold air in. The air from outside is often full of moisture and this perpetuates mold and mildew. This air leakage is not only physically uncomfortable, but financially uncomfortable as well. In fact, your utility bills can increase by 20-30% due to the necessary energy demand. Now, with the onset of winter, you'll want to both keep your home warm and keep money in your pocket.
Sealing and Insulating
So...where exactly does the air leak into the house? In your attic there are several different places that you have to check and seal. First, however, you want to make sure your attic insulation is up to code - currently R-49. If you gain access to your attic via a pull down ladder, don’t forget to insulate the hatch as well. It's commonly forgotten and, as a result, can cause unpleasant drafts and air leakage.
Insulation doesn’t entirely keep warm air from escaping your home, but it does slow the flow of warm air significantly. The R-value is the measured effectiveness of the insulation’s ability to capture and slow movement of warm air. In attics, it is recommended to have an R-value of 49. This is achieved by installing the proper thickness of insulation for the type of material you're using. For example loose-fill cellulose has an R-value of 3.7 for every inch, so you'd want just over 13" of that material.
Next are any possible openings. These can range from the joints between wall and ceiling, any joints at interior walls, ceiling light fixtures, chimney or vent entrances, and electrical wiring. There are quite a few of these, but thankfully they are not too hard to seal up. Spray foam or caulking can be used for blocking most of these openings.
While much of this you can do yourself, it may be in your best interests to hire a professional. Air leaks can be easily missed when trying to seal all the holes, and if you need a vapor barrier or a ventilation system, installation will likely be difficult and unfamiliar. Hiring a weatherization expert, even after a quick DIY repair, will be money well spent.