Unless you live in a home built specifically for energy efficiency, you can probably save energy by adding insulation to the attic. Many older homes have less insulation than the amount professionals recommend. Adding insulation is most likely a cost-effective decision, but you need to determine a few things before you get started.
How Much Insulation Do I Currently Have?
Take a quick visit up to the attic armed with a ruler to determine how much insulation is there. Insert the ruler through the insulation until it makes contact with the attic floor. If it’s clear the insulation level is well under 12 inches, or you cannot see the floor joists, you could certainly benefit from adding more. If you cannot or don’t feel comfortable doing this on your own, professionals can help.
How Much Insulation Should I Add?
Austin is in a warm climate characterized as Zone 2. This means your attic should be insulated to an R-value, or heat flow resistance value, of R-30 to R-60. The most cost-effective R-value is about R-38.
If you have fiberglass batts or rolls, this means you need 8 inches of high-density insulation at the very least. One foot of standard-density fiberglass batts offer an insulating value of R-38. Loose-fill insulation is another popular option for attic floors. One foot of rock wool loose-fill insulation is rated at R-36.
This means if you have 3 to 4 inches of existing insulation, you should add 9 to 10 more inches. You don’t need to worry about figuring these numbers out on your own; a professional will be able to determine how much you need.
Can I Add New Insulation over Old Insulation?
Now it’s time to answer the question you’re been asking yourself: “Can I add new insulation over old insulation, or do I need to remove what’s there and start from scratch?” It depends! You can add extra layers over existing insulation, and you don’t even have to use the same type of insulation that currently exists on the attic floor. For example, you can add fiberglass batts or rolls on top of loose-fill insulation, and vice-versa.
If you select batts or rolls for your added layer, just make sure you select the type that has no foil, vinyl or paper backing. Called “insulation facings,” these materials are for air and vapor barrier purposes. They should be placed directly against the attic floor.
But there are some cases where you may need to remove insulation and install new material (like if your insulation is old or damaged).
For more tips about insulating your home, or for help installing attic insulation, contact Hinkle Insulation for a free consultation.