Insulation. Thrilling? Not to most. But when it comes down to comfort and energy use in your home, insulation is the name of the game.
The basic function of insulation is simple: to stop airflow between the indoors and out. In the summer, it means keeping hot air out, and in winter, it means keeping warm air in.
This fall, add insulation to your winter prep checklist to reduce your energy spend and have a more enjoyable time indoors through the darkest months of the year. Need help on where to start? Keep reading — we’ll tell you what to look for with insulation, how it’s sold, and what your options are when it comes to materials.
The R-Value
The single most important thing to know about insulation is its R rating. The “R” simply stands for resistance to heat flow. The Federal Trade Commission (FTC) enforces the “R-value rule” in insulation, meaning nearly all manufacturers have to provide the accurate R-value of the material.
The R-value might be easy to find, but you need to know what R-value is appropriate for your space. There are a few factors that come into play here:
- Where do you live? Homes in the Northeast will naturally require a higher R-value than homes in southern California. Check out this map from Energy Star for a handy guide.
- How was your home built? Is it a single-level or multi-level? Do you have a basement? High cathedral ceilings? Each of these factors will contribute to the type of insulation appropriate for your home.
- How do you heat and cool your home? Your insulation decision will be impacted by your HVAC system: do you have central air, a furnace, or heat your home with a wood stove?
How Insulation is Sold
There are a few different ways in which you can purchase insulation. The most common form is blanket insulation, which is sold in rolls or batts. The majority of the insulation types we’ll cover below are sold in this form.
You may also encounter loose-fill insulation. This insulation consists of small particles of fiber, foam, and other materials. It conforms easily, making it good for retrofits, and is installed by either pouring directly from the bag or applying with a blower.
Traditional Insulation Materials
You’ll most commonly encounter insulation that’s made traditionally from foam or fiberglass. Here’s a quick breakdown:
Fiberglass Insulation – has an R-value of 3.0 to
4.0 per inch. The benefit of fiberglass 
insulation is that it’s widely available and therefore affordable. The downside: you have to wear protective clothing to install (it’s itchy!), and rolls have to be cut my hand to fit unique spaces.
Rockwool Insulation – earns an R-value of 4.0 to 5.0 per inch. Also sold in batts, rockwool is more fire-resistant than fiberglass, doesn’t itch, and springs into shape, making installation easy. The downside: rockwool is harder to come by and retains moisture, meaning it can harbor mold growth.
Spray Foam Insulation – depending on the type, the R-value can range from 3.5 to 6.5 per inch. Boasting a higher R-value than fiberglass, spray foam also ends up being a bit more costly. Spray foam effectively creates an air barrier, but is often best left to the pros to apply.
New insulation materials
Traditional materials are still very much prevalent, and are no longer manufactured with damaging CFCs (chlorofluorocarbons). Still, the HCFCs (hydrochlorofluorocarbons) used instead have an impact on the environment, and make it risky for DIY installation.
Because of that, alternatives are popping up left and right that are both easier to work with, and less harmful to the environment.
Wool – sustainable sheep’s wool has an R-value of 3.5 to 3.8 per inch and is breathable, absorbing and releasing moisture without affecting its insulation performance. Safe to handle, wool is also noncombustible, making it more resistant to fire than fiberglass.
Cotton – has an R-value of 3.2 to 3.7 per inch. Typically made from recycled denim, cotton insulation is formaldehyde free. It is also more noise-resistant and safe to handle. But it comes at a cost: cotton insulation is approximately double the price of fiberglass.
Cork – expanded cork carries an R-value of 3.6 per inch. The loose granules are sold in bags and make it easy to fill awkward gaps and spaces. Does cork seem like a strange material to you? Check out this great article from Houzz.com on the “unstoppable advantages of cork for the home.”
Recycled plastic – perhaps better known as Supaloft green, this insulation is itch-free and 90 percent of it is made from plastic bottles.
Choosing the right insulation
Keep this in mind: you want to pick the best, most efficient insulation for your home. If you choose an eco-friendly material, it should be because it improves upon your home’s energy performance. A tip: to get the most from your insulation, proper installation is key.