How much blown in insulation is needed in attic?

Asked By: Sanjaya Moidu | Last Updated: 1st February, 2020
Category: home and garden indoor environmental quality
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Blown-In Attic Insulation Costs
The cost to insulate an attic with blown-in insulation runs from $600 to $1,200, assuming it is 1,000 square feet in size. If you choose to hire a professional, expect to pay from $40 to $70 an hour for labor in addition to the cost of materials.

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Keeping this in view, how much insulation do I need in the attic?

According to the U.S. Department of Energy, it's recommended that attics have an R-38 to R-49, or about 12” to 15” of fiberglass or cellulose insulation. Use unfaced insulation when adding more insulation to an attic that already has some insulation, laying the rolls or batts at right angles to the floor joists.

Also Know, how much blown insulation do I need calculator? Example Calculation = 12 Area = 10 * 6 = 60 square ft Required depth to achieve R value needed = R 12 / R 3.6 = 3.3 inches Volume needed = 60sq ft * 0.275 (3.3 /12 converting to decimal ft) = 16.5 cubic feet You would need one bag in this case. Note: the cost is based on rounding up the number of bags needed.

Furthermore, how do I measure for blown insulation in my attic?

Cellulose blow-in insulation is constructed out of recycled paper. To determine how much cellulose insulation you need, take the square footage of the space and divide it by either the depth or the desired R-value. Fiberglass blow-in insulation is essentially made up of spun fibers from recycled molten glass.

How much does blown attic insulation cost?

Blown in Insulation Overview The pros charge $1,500 to $2,000 to do a 1,200-sq. -ft. house. You can do it yourself for about $500.

29 Related Question Answers Found

Can you put too much insulation in attic?

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. This is not to say that if you have mold in your home, too much insulation is the culprit.

What is the best blown in insulation for attic?

The best insulation options for an attic are open cell spray foam, fiberglass, and cellulose.
  • Cellulose is the oldest insulation material used for not only the attic, but other areas of the home as well.
  • Fiberglass is another traditional insulation material that consists of extremely fine glass fibers.

How do you seal an attic?

Plug the big holes first.
  1. Create stuffed bags.
  2. Plug open stud cavities.
  3. Cover dropped soffits.
  4. Seal behind kneewalls.
  5. Cut aluminum flashing.
  6. Seal with silicone caulk.
  7. Form an insulation dam.
  8. Find attic bypasses.

How do I know if my attic needs insulation?


A quick way to see if you need more insulation is to look across your attic floor. If your insulation level is at or below the top of the floor joists, you probably need to add more insulation (but remember to seal the air leaks before you insulate).

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.

Should I remove old blown in insulation?

Remove Old Insulation
Once there is no asbestos, mold, or rodents, it is generally safe to proceed with attic insulation removal yourself. Luckily homeowners are more likely to find the easier kind which is blown-in fiberglass or cellulose insulation. Removing rolls or batting is a bit harder, but can be done.

How much does blown in insulation cost?

Blown-in insulation is about $1,443, with most homeowners spending between $927 and $2,025, but this is dependent on whether the work is done by the homeowner or by a professional. Blown-in insulation (also called loose fill) runs from $1 to $1.50 per square foot.

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.

When should you replace attic insulation?


Insulation should also be replaced, in some cases sooner than 15 years, if it is no longer doing its job properly. You'll know it needs to be replaced if there are insulation leaks or if it is peeling from the walls.

How many sq ft does a bag of insulation cover?

10 bags/pallet is equal to 110-pieces/1065.60 sq. ft. The right insulation can save on energy and heating and cooling bills. Check out our Buying Guide for helpful tips.

Is blown in insulation safe to breathe?

Safely handling fiberglass
When fiberglass insulation is moved or disturbed, it releases tiny particles into the air. If they get on bare skin they can lodge into pores and cause itching, rashes, or irritations. If they are inhaled, they can result in coughing, nosebleeds, and/or respiratory problems.

How deep is r30 blown insulation?

Blown in Fiberglass Attic Insulation
R-Value Minimum Thickness Bags per 1000 sq ft of net area
R44 17.4” 26.9
R38 15.3” 22.9
R30 12.4” 17.6
R19 8.1” 10.8

What R value do I need for attic?

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.

How do I calculate how much insulation I need?


Measure the height and width of any windows or doors in the wall. Multiply the measurements to find the area of each window or door, and subtract them from the total square footage of the wall. This gives you the square footage of insulation you need for that wall.

What is the R value of 12 inches of blown insulation?

R-value of Materials and Depths
Material R-value/in 12"
Fiberglass blown (attic) 2.2 - 4.3 26.4 - 51.6
Fiberglass blown (wall) 3.7 - 4.3 44.4 - 51.6
Mineral Wool (batt) 3.1 - 3.4 37.2 - 40.8

How long does it take to insulate an attic?

Attics - Insulating an attic could take one to two days. This depends on how much old insulation in the attics must be removed. A separate removal crew may come out a day or two before the installation date to remove the old insulation. Once the install crew is there, in most cases the attic can be insulated in a day.