1 of 6
Fiberglass insulation being blown onto an attic floor. The finished R-value is more important than the initial thickness.
Source: Certainteed
2 of 6
Foam insulation being installed in a wall. It expands to many times its initial volume to fill all voids. The excess is easily trimmed off.
Source: Icynene
3 of 6
Standard fiberglass blanket/batt insulation being installed in a wall. The kraft paper vapor barrier is stapled to the wall studs.
Source: Owens Corning
4 of 6
Fiberglass insulation is encapsulated in a poly vapor barrier cover to make it easy to install and minimize itching while working with it.
Source: Owens Corning
5 of 6
This batt insulation is made from recycled cotton denim from blue jean production waste. It is treated for fire safety.
Source: Bonded Logic
6 of 6
A retaining strip is being snapped into the mounting track to hold these insulating wall panels up against a concrete block wall.
Source: Owens Corning
Question: My house feels chilly. Will adding more insulation make me feel warmer and cut my utility bills? What's the best type of insulation to use for this and for a new room addition?
Answer: A well-insulated space will certainly make you feel more comfortable. In a room at 70 degrees with little wall insulation, you may still feel chilly, because the exterior walls are cold and your body is losing its warmth by radiant heat transfer to the walls. During the summer, a hot wall will make you feel uncomfortably warm.
Generally speaking, adding insulation to the walls or ceiling of a house will reduce monthly utility bills. The actual savings for each home depends on several factors—the current level of insulation, your climate, the efficiency of your heating/cooling system and your utility rates.
Your current level of insulation is perhaps the most important factor in deciding whether or not to add more insulation and how much. For example, doubling the amount of insulation in your attic will typically cut the heat loss through the room ceiling by about half. Your contractor can help you determine the payback from the savings as compared to the installation costs.
But if you double that amount again, it will cut the original heat by only another 25 percent (half of half). This diminishing return is important to keep in mind when determining the amount of insulation to add.
Various types of insulation can be used to reduce conductive heat loss and/or radiant heat loss. Standard fiberglass batts, blown-in fiberglass, cellulose, rock wool and foam are all used to block conductive heat loss. This is the kind of heat transfer that travels through materials, such as drywall, studs and bricks.
Radiant heat transfer is the way the sun heats the Earth or how you feel heat standing next to a fireplace, even though the hot air is going up the chimney. Your house also loses heat to the cold outdoor air and nighttime sky by this method. Radiant barrier types of insulation, such as an aluminum foil film, are effective for blocking this heat loss. Some standard insulation batts include a foil facing to reduce both types of heat loss.
No single type of insulation is “best” to use in all locations in your house. What’s important when selecting insulation is its installed R-value. Don’t confuse that with thickness—some types of insulation have twice the R-value per inch thickness as others. Also, blown-in insulation can be fluffed up when installed, not necessarily intentionally, resulting in less accurate R-value. Make sure your insulation contract specifies the final insulation value, not just the thickness.
Fiberglass insulation is made basically from sand. Some manufacturers use 25 percent recycled glass, so check the packaging if you prefer recycled products. Rock wool insulation is made primarily from waste products. It and fiberglass have an insulation value of about R-3 per inch of thickness.
You might also consider an environmentally friendly insulation made of recycled materials. One type is made from scrap blue jean material production. It looks similar to chopped up blue jeans in batt form. It is treated for fire safety and has an insulating R-value similar to fiberglass batts.
If the amount of space available for the insulation is limited, as in a masonry wall, injected foam is a good option. Some polyurethane foams have an R-value twice that of fiberglass, so only half the thickness is needed. The closed-cell foam also creates its own vapor barrier and stops air leaks. Look for foam that uses no ozone-layer-damaging foaming agents.
Another option to minimize voids is called a blown-in-blanket method. This works well for a room addition. First, a special film is stapled up over the wall studs. Next, loose-fill insulation is blown into the wall cavity to eliminate all voids. Then it is smoothed out through the film, and the drywall is nailed over it. Another similar system adds some binders to the insulation to reduce settling over time.
Send questions to Energy Q&A.
_____
Get More
The following companies offer insulation materials:
Bonded Logic, (480) 812-9114
Certainteed, (800) 782-8777
Johns Manville, (800) 654-3103
Owens Corning, (800) 438-7465.
_____
Related Stories