Thickness of R-38 Insulation
R-Value is a measure of insulation’s ability to resist heat flow. The higher the R-Value, the better the thermal performance of the insulation. The recommended level for most attics is to insulate to R-38 or about 10 to 14 inches, depending on insulation type.
Similarly, what is the difference between r30 and r38 insulation? The bigger the R value, the better the insulation is at slowing down the heat transfer. So R19 is better insulation than R13, and R30 is better than R19. The larger the R value, the better the insulation value. This means you could use R38 insulation, and then add another layer of R13, for a total of R51….
Furthermore, how thick should cellulose insulation be in attic?
For loose-fill cellulose, this translates to a total depth ranging from 8 inches up to 16 inches. Fortunately, attic insulation can be upgraded simply by adding more to achieve the recommended total depth in inches, without removing existing insulation.
How do I calculate the R value in my attic?
To find the R–value of the existing insulation in your attic, multiply the number of inches of insulation by the R–value for your particular type.
Cold Climates (R-49 to R-60):
- Fiberglass (blown): 19” – 25”
- Fiberglass (batts): 14” – 19”
- Cellulose (blown): 14” – 18”
- Rock Wool (loose): 17” – 25”
- Foam (sprayed): 7” – 15”
Can you over insulate your attic?
According to ENERGY STAR®, you can put new insulation over old insulation, “unless it is wet. 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.
How many inches is r30?
For future reference, here is the cavity depth you need for some common insulation r-values: 3.5 inches — R13. 6 inches — R19. 9 inches — R30.
How often should you insulate your attic?
Most experts, including those at the U.S. Department of Energy, recommend that you have you insulation inspected at least once a year. If your roof has had to be repaired or replaced because of leaks, you should definitely make sure to have an attic insulation inspection.
Can you over insulate a house?
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.
What does it cost to insulate an attic?
It can cost anywhere from $1,700 to $2,100 or between $1.50 and $3.50 per foot to insulate an attic depending on what insulation material you choose. Blown-in insulation is the least expensive option and ideal for older attics. Spray foam, while the most expensive, is best for noise reduction and new construction.
What is the best insulation for attic?
Loose-Fill Insulation Cellulose is the most effective material and has an R-value of 2.2 to 3.8 per inch, but if exposed to moisture it can get moldy.
Is r19 good for attic?
Most homes only have R19 in attics. To give you an idea that’s only 5 1/2 inches of insulation. So by adding another R19 “5 1/2 inches will give you an R38 value. And that’s a good number to live with.
What is R 49 insulation thickness?
Flexible fiber glass insulation 14 Inches thick. Size: 14 in x 16 in x 48 in. R-Value: R49.
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.
Should I remove old attic 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.
Is air sealing the attic worth it?
Air sealing your attic is essential to an energy efficient home. Air sealing your attic and having it appropriately insulated helps minimize the stack effect. This will make your home’s temperature more comfortable and easy to regulate, while protecting you against high energy costs year-round.
Which is better cellulose or fiberglass blown in insulation?
Cellulose Vs Fiberglass which blown in insulation material is best: When it comes to air infiltration cellulose is a better choice because it has 38% better air infiltration than fiberglass. Cellulose properly insulates the attic because it forms a dense continuous mat and keeps the air moving within the insulation.
How do you know if blown in insulation has asbestos in it?
Signs Insulation May Contain Asbestos If your insulation is gray-brown or silver-gold, chances are it’s time to call a professional. If your loose-fill insulation is a dull gray, and soft – it’s a good bet that your insulation is mineral-based and asbestos-free.
What is the proper way to insulate an attic?
There are two basic ways to insulate a finished attic. If only the living space will be insulated, wrap the insulation around the room’s walls and ceiling and then continue along the floor of the non-living space. In this case, the area behind the knee wall will be uncomfortably hot or cold.