In general, either batt or rolled insulation or blown
You should install two layers of insulation in your attic; wood joists must be covered to allow the air to move. The first layer will sit between the joists, and the second layer will run perpendicular over the joists. The first layer should have the facing against the drywall to act as a vapor barrier.
Blown-in insulation is often installed in attics and other tightly enclosed spaces. If blown-in insulation was previously installed in one or more areas of your home, it is perfectly acceptable to also add rolled insulation. There is one caveat, however. You need to avoid faced insulation.
The dip from R10 to R4 seems odd, as one would expect more R as you travel further north through the zones. Thicker is not better! Doubling the amount of insulation will double the R-Value, but so what? Doubling the insulation from R-19 to R-38 does NOT cut the heat loss in half (50%) it cuts it by around 3%!
It's usually not recommended to have insulation in both the ceiling and floor of an attic because this creates a ``dead air space'' which can be prone to moisture problems. What happens is that moisture from the house can move up into the attic.
While over-insulated attics aren't as common as under-insulated attics, it is possible to put so much insulation in your attic that it has a negative impact.
If your building is located in an area with extreme weather conditions, double insulation can be a game-changer. For instance, in regions with harsh winters, double insulation can prevent heat loss, keeping the interior warm and comfortable.
Because its structure is more complex than single-layer insulation, the cost is relatively high. Additionally, in some cases, double-insulated cables may fail due to spalling between the inner and outer insulation layers.
R19 Insulation offers superior thermal insulation compared to R13. With a typical thickness of 6.25 inches, R19 fiberglass is designed for use in 2x6 wall cavities, making them suitable for colder climates where higher thermal resistance is necessary.
When you stack new insulation on top of existing attic insulation, the existing insulation is compressed a small amount. This will slightly decrease the R-value of the existing insulation. This effect is most important if the new insulation is more dense than the old insulation.
Now that you've air-sealed your attic and basement, check your attic insulation levels and add more if necessary. The attic is the easiest place to add insulation to improve your comfort and the energy efficiency of your home.
If the existing attic insulation is an R-19, you may choose to add another layer of R-19. Two layers of R-19 at 6¼ ” thick will achieve a total R-value of 38. So adding an R-19 batt to an existing R-19 batt will give you a total insulation value of R-38.
In many cases you can add new insulation on top of old insulation, unless the old insulation is wet, mouldy, or vermiculite. If the old insulation is dry but appears to have previously been wet, you should look for the cause and repair the problem.
Easier to heat and cool: When you have quality attic insulation, more heat stays in your home through the winter, and less radiates down from your attic in the summer. This resistance to heat makes it more affordable to heat or cool your home to the temperature you're comfortable with.
Generally speaking, vapor barriers are considered an essential moisture-blocking tool for climates that experience significant levels of humidity. For that reason, building codes in more humid locations will often require them, in which case you might not have much say about whether to install one or not.
You will want to bring up your attic up to R-38:
If your attic has 5-6″ of existing insulation, you'll want to install an R-19 to achieve a total of R-38.
R15 insulation offers slightly better thermal insulative properties than R13. Some of its formats are a fraction of an inch thicker than R13, making it more effective at helping with energy efficiency. However, the difference is minimal. R15 is slightly thicker than R13 for spray foam and blown-in cellulose.
The recommended R-value for attic insulation can vary depending on the climate zone in which you live. The U.S. Department of Energy recommends attic insulation levels of R-49 to R-60 for most homes in colder climates, and R-30 to R-49 for homes in warmer climates.
By doubling the insulation layers in your loft, you increase its R-value, which in turn reduces its U-value (lower U-value is better). This results in better insulation and improved energy efficiency for your living space.
For most long-term applications, double bubble foil insulation is going to be the better option to use. Because of the double layer of polyethylene bubbles, double bubble insulation provides the most effective thermal break, making it harder for radiant heat to transfer through than with single bubble insulation.
Options. Option: When installing multiple layers of insulation for optimal thermal performance, install the first layer (bottom layer) parallel to attic framing members and flush with both bottom and top. Install the second layer (top layer) perpendicular to attic framing members.
Double insulation eliminates the risk of electric shock without relying on grounding or a safety extra-low voltage power source. Most household and office appliances rely primarily on this insulation for user safety. That's why safety regulations worldwide classify electrical devices based on their insulation system.
It is possible to over-insulate your house so much that it can't breathe. The whole point of home insulation is to tightly seal your home's interior. But if it becomes too tightly sealed with too many layers of insulation, moisture can get trapped inside those layers. That's when mold starts to grow.
Depending on where you live and the part of your home you're insulating (walls, crawlspace, attic, etc.), you'll need a different R-Value. 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.