Insulation levels are specified by
Mold and Mildew Growth
Having too much insulation in your attic can allow for the accumulation of moisture. This leads to mold and mildew growth, which can be extremely bad for your health.
(R303. 1.1. 1) Blown-in or Sprayed Roof and Ceiling Insulation | UpCodes.
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.
Fiberglass, cotton, and mineral wool can all work as loose-fill insulation material, but the far and away top choice for blown-in insulation is fiberglass. Contrary to batts insulation, blown-in fiberglass insulation is perfect for filling in tight voids around wiring, pipes, or any area with awkward framing.
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.
New homes: Insulating attic walls in a newly constructed home with blown-in insulation costs $2 to $4 per square foot. Attic: Insulating an attic using blown-in insulation costs between $3 to $7.50 per square foot.
Also, when laying down additional insulation, work from the perimeter toward the attic opening. Never lay insulation over recessed light fixtures or soffit vents. Keep all insulation at least 3 inches away from recessed "can" lights, unless they are rated IC (Insulated Ceiling).
Cons of Blown-In Attic Insulation:
Poor installation can lead to uneven coverage, material waste, and even structural issues like sagging ceilings. Hiring a skilled installer is crucial to getting the most out of this insulation type.
R 40: Thickness that oscillates between 13 and 15 inches. R 50: Thickness that oscillates between 15 and 19 inches. R 60: Thickness that oscillates between 19 and 22 inches.
Both cellulose and fiberglass are energy-efficient insulation materials, but cellulose has a slight edge due to its higher R-value. The R-value for cellulose insulation is approximately 3.2 to 3.8 per inch, while fiberglass insulation typically has an R-value of 2.2 to 2.7 per inch.
Rolled insulation generally has a lower upfront cost than blown insulation. However, blown insulation tends to have a higher R-value, meaning it can provide superior attic insulation, creating potential for cost savings on heating and cooling bills in the long term.
If your attic has little or no existing insulation, you'll want to install an R-38 rated material. If your attic has 2-3″ of existing insulation, you'll want to install an R-30 to achieve a total of 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.
The average cost to spray foam insulate garage wall insulation is $500 to $3,000. A 24x24' 2-car garage wall has a dimension of 576 sq ft. The cost of insulate the walls with R13 - R21 depends on the type of insulation installed. The labor cost for insulating the 2-car garage wall is $1,500 - $3,500.
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.
Do I Have To Remove Old Insulation? Unless your insulation is wet, moldy or infested with pests, you don't need to remove it before adding insulation on top of it. ENERGY STAR® recommends that you inspect your insulation for signs of mold, mildew, moisture and pest infiltration before making this determination.
If you live in the Southern part of the U.S., the recommended insulation level is a minimum of R-38 or about 13-14 inches of insulation. If you live in the Northern part of the U.S., the recommended insulation level is a minimum of R-49 or about 16-18 inches of insulation.
On average, you can save up to 20% on your home's heating and cooling costs or up to 10% on its total energy costs by adding insulation to attics, floors, crawl spaces, and accessible basement rim joists, and by reducing unwanted air leaks all around your house.