A: There's no problem with installing fiberglass batts over your existing blown-in insulation. If you install faced insulation over existing blown-in, you're essentially putting the vapor barrier in the middle, between the two layers of insulation.Just so, can you layer faced insulation?
“Faced” insulation should not be placed on top of existing insulation in the attic. Any new batt or roll insulation installed over existing insulation in the attic needs to be without a vapor retarder (face). The vapor retarder on top of or between layers of insulation can trap moisture.
One may also ask, how do you install two layers of insulation? If you have paper faced insulation put the first layer (paper side) toward the warm part of the house. Place the second layer paper side up toward the roof and then run your utility knife through the paper. This will allow any moisture to escape. As others have said run the second layer perpendicular to the first.
Also know, can I double up r13 insulation?
If you have a 2x6 R13 should not be used period, it's not thick enough, perhaps this is why your contractor thinks he can double them up. Edit: the other problem with doubling up batts is that the paper on the batts can trap moisture. If you have a moisture issue it wouldn't breathe properly and could grow mold.
Can you put too much insulation in your attic?
But there may be a theoretical point of “too much.” If a home is over-insulated and is too tightly sealed, moisture can get trapped inside. Without proper ventilation, a home can build up too much moisture, especially in the attic (warm air rises), which can cause mold problems and, overall, lower indoor air quality.
When should you not use faced insulation?
Unfaced insulation—the type without paper—is what you would use if you are adding insulation to your attic or to place between floors when living space is above and below. Unfaced is also your best choice for adding soundproofing to interior walls.Is rolled insulation better than blown?
Blown fiberglass insulation scores an R-value of 3.2 to 3.8, making it slightly less likely than rolled fiberglass to prevent the flow of heat into and out of your house. That being said, though, blown fiberglass insulation isn't meant to cover huge areas like rolled fiberglass insulation.Does doubling the insulation increase the R value?
Doubling the thickness of insulation will double the insulation's R-value, cutting heat loss in half. The energy saved per year by doubling insulation from R-10 to R-20, however, will be considerably more than the energy saved by doubling insulation from R-20 to R-40, because of the law of diminishing returns.How many inches of insulation should be in my attic?
The recommended level for most attics is to insulate to R-38 or about 10 to 14 inches, depending on insulation type.Can you roll insulation over blown insulation?
According to ENERGY STAR, you can put new insulation over old insulation, “unless it is wet. Batt or rolled insulation or blown loose-fill insulation (fiberglass or cellulose) can be installed on top of old insulation. Insulation should be rolled out perpendicular to the joists—and unfaced rolls should be used.Should you remove old insulation before adding new?
Do I Need to Remove Old Insulation Before Adding New Attic Insulation? Your current attic insulation will form the basis of the additional attic insulation that you are planning to install. Therefore, unless it is damaged or your roof is damaged, you should not have to remove the original insulation.Can you mix insulation types?
You can mix and match the various kinds of insulation. For example, if you have cellulose insulation, and more insulation is needed, you can add any type you wish. It is also acceptable to use batts over loose-fill material and loose-fill material over batts.Does attic insulation need to be faced?
You can use either faced or unfaced batting for this installation. When using insulation that has either paper or plastic facing, that moisture barrier faces outward, toward the attic space. Even if the attic space is unheated, it typically is warmer than the outside air in winter.Can you put r19 in 2x4 walls?
R19 in a 2×6 wall does not really give you an R19 wall. It is about a R16 wall because of the feect of the “thermal short circuiting” through the studs. If it is a 6″ steel stud wall, it could be as low as an R11 wall.What is a good R value for exterior walls?
Typical recommendations for exterior walls are R-13 to R-23, while R-30, R-38 and R-49 are common for ceilings and attic spaces. See the Department of Energy's (DOE) ranges for recommended levels of insulation below.Does compressed insulation lose R value?
A. When you compress fiber glass batt insulation, the R-value per inch goes up, but the overall R-value goes down because you have less inches or thickness of insulation. For every x% the insulation material is compressed, the R-value decreases by approximately one half of that percentage or ½ x% compressed.Is r13 insulation good for exterior walls?
Although the U.S. Department of Energy rates R-13 insulation as "good" for use in walls in southern areas of the country, it rates R-19 insulation higher, designating it as "great." That is because R-19 insulation provides more thermal insulation than R-13 does.Will 2x6 insulation work in 2x4 walls?
Insulation for 2x6 Walls Use R-19 or R-21 kraft-faced fiberglass insulation for two-by-six (2x6) walls. This combination ensures that the insulation is neither too loose nor too tightly packed within the walls. Two-by-four (2x4) stud walls with true 4-inch depth.Is there a big difference between r13 and r15?
R15 should be better than R13 by a little bit in the wall. If you have steel studs instead of wood, then the R15 and R13 walls would be about the same because of high conductivity of the steel. You will never get an R15 wall with R15 insulation if it was tested as a composite system.How thick is r60 fiberglass insulation?
In temperate coastal areas such as Zone 3, attic insulation of at least R30 up to a maximum of R60 is recommended. For loose-fill cellulose, this translates to a total depth ranging from 8 inches up to 16 inches.Can you double up foam board insulation?
4 Answers. Yes, Rigid foam (XPS and ISO) boards are frequently used in exterior applications, and can be a great option for improving efficiency. You also do not usually need an extra vapor barrier layer adjacent to rigid foam sheets, they are typically highly resistant to moisture.What does r13 mean with insulation?
Basically, that means more insulating power. So it takes longer for heat to go through the R30 insulation than it does to go through the R13 insulation. 
