Weatherizing your house doesn’t only mean getting it ready for the cold winter months, it’s for all year long; luckily one of the easiest things you can do to weatherize is also one that makes the biggest impact: attic insulation.
Dollar for dollar, attic insulation is one of the most cost-effective improvements you can make to your home. Around 30% of the heat in your home is lost through your attic in the winter, and in the summer a poorly insulated attic lets in significantly more heat from the sun. Do you have enough insulation to keep the heat where it belongs?
Your first step is to go to your attic.
Look around at the level of insulation you see. Is it at or below the level of your joists? If so, you need more. If it’s above your joists, you’re probably fine…unless it’s distributed unevenly. Check for spots that don’t have enough, especially around the edges.
If you need to add more, your questions are probably How much more? and, What type should I use?
To determine how much insulation you need, look at what type and how much you currently have. Each type of insulation has its own measure of how well is resists heat flow, or its R-value. This is usually given on a per-inch basis; for instance, blown-in loose fiberglass has a value of R-2.5 per inch. If you have 10 inches of fiberglass, your attic has a current R-value of 25.
The optimal R-value depends upon your climate; here in the Raleigh area, R-30 to R-60 is a good goal. If you’re using blown-in fiberglass to insulate, which has a 2.5 R-value per inch of depth, you should have 12 inches for an R-30 value and up to 24 inches for an R-60 value.
The three most common types of insulation are:
- Cellulose – Made from recycled newsprint and other types of paper.
- Fiberglass (blown-in) – Same “fluffy” appearance as cellulose, but made of spun glass.
- Batts – Rolls of fiberglass insulation commonly found in hardware stores.
Cellulose and blown-in fiberglass generally provide more consistent coverage than batts, and therefore are generally more energy efficient. However, there are some big differences between the two that you will want to consider:
- Blown cellulose can pose a fire hazard, especially if there are any light fixtures installed near it. It releases dust during and after installation. Due to the amount of dust in blown cellulose, nothing can be safely stored in the same area as the insulation; if you’re planning on using your attic for any type of storage, you do not want to install blown cellulose.
- Blown fiberglass, on the other hand, does not pose any fire hazard, nor is it dirty or dusty. While in the past it has had the reputation for being itchy, modern Owens Corning blown fiberglass is safe enough to rub on your skin and feels like a cotton ball. It’s perfect for an attic that will have lights and/or be used as storage.
If you need to add new insulation, it is possible to do it yourself, but much easier and more consistent results are obtained by a professional who is trained in the safe installation of insulation.
If you have a home with insulation that may have been produced before 1990, have a professional look at your insulation before doing anything. It is possible your insulation may have asbestos in it, and should only be handled by certified professionals.
Don’t wait for winter to ensure that your attic is properly insulated; summer’s heat creates the need for a well-insulated attic as well. Before it gets too hot, head to the attic and see if your insulation is up for the task of keeping your home comfortable all year round.