What is the recommended level of attic insulation?

Author: Bernardo Walsh  |  Last update: Monday, June 2, 2025

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.

What R-value is best for attic insulation?

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.

Is R19 or R30 better for an attic?

Yes, you can use R19 insulation in an attic, but whether it's suitable depends on a few factors: Climate Zone: R19 insulation is typically appropriate for attics in moderate climates. In colder climates, higher R-values (like R30 or R38) may be recommended to effectively prevent heat loss.

Can you put too much insulation in your attic?

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.

What thickness is best for attic insulation?

However, the DOE recommends that attics in Southern homes be insulated with 13 to 14 inches, or R-38, of insulation at minimum. Northern homes should have attics with 16 to 18 inches of insulation or R-49. If your home isn't insulated to the recommended thickness, you likely want to consider adding more insulation.

Insulation R-VALUE - What is R-Value?

Should old attic insulation be removed?

The bottom line is the old insulation needs to be removed because it hinders the airflow into the attic, it can promote mold growth, and it is dirty.

Should I use r30 or r38 for attic?

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.

Where should you not put insulation in the attic?

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).

Can I double up R13 insulation?

Adding two R-13, 3.5” batts to a 2”x6” (5.5”) wood stud cavity will not provide an R-26. The total of 7” of insulation is reduced in thickness to 5.5” thereby losing the R-value associated with its full thickness.

What is the best insulation for attics?

Fiberglass Batt and Roll Insulation

Fiberglass batt and roll insulation is a common and budget-friendly option. This insulation comes in pre-cut batts or long rolls, making it easy to fit between the framing members, like joists and trusses, in your attic.

Does doubling insulation double R-value?

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%!

Is R19 worth it over R13?

R13 insulation is generally more affordable, which makes it an attractive option for budget-conscious projects. However, R19 insulation offers better long-term advantages because of its higher R-value. Why? Because the R-Value translates to a greater energy savings over time.

Do I need faced or unfaced insulation in my attic?

Typically, you use unfaced insulation when you plan to add more insulation to your attic or between the walls and floors of your living spaces at home.

What insulation board has the best R-value?

The best kind of rigid foam insulation is polyisocyanurate, also known as polyiso. It has the highest R-rating of any rigid foam insulation and comes with a reflective foil on both sides, allowing it to act as a radiant barrier as well.

Is extra attic insulation worth it?

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.

Is it okay to put plywood over insulation in an attic?

Can I put plywood over insulation in the attic? Yes you can install plywood subflooring directly over the floor joists and insulation on your floor. You need to install rigid insulation boards on top of the attic flooring joists and then install plywood over the top.

Does attic insulation qualify for tax credits?

IRS Form 5695: Claiming Energy Tax Credits

Use IRS Form 5695 to claim energy tax credits for various home improvements. This includes attic insulation. Annual limits are set at $1,200 for envelope improvements like insulation and windows and up to $2,000 for systems like heat pumps.

Can an attic be too insulated?

Too much insulation will leave humidity and moisture to accumulate in your attic space. This can lead to mold growth on your walls and insulation. There might also be water damage to the support beams in your home's roof.

How many inches of insulation should you put in your attic?

The recommended level for most attics is to insulate to R-38 or about 10 to 14 inches, depending on insulation type.

Is R15 worth it over R13?

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.

Is R60 attic insulation worth it?

If the federal recommendation is R60, then you can save yourself plenty of money on energy bills and HVAC repairs by having a minimum of R60 installed. This can be any combination of batts and blown-in insulation.

What is the life expectancy of attic insulation?

Conclusion. Attic insulation can last 80 to 100 years, though it loses its energy efficiency benefits with time. Certified attic specialists' professional advice is to upgrade it every 15 years to ensure that it is still performing the job.

Do you need ventilation in attic after you insulate?

At first it may seem odd to add insulation for warmth and then purposely allow cold air to enter the attic through vents, but this combination is the key to a durable and energy-efficient home.

What is the best insulation for the attic?

Fiberglass batt is considered to be the best insulation for attics. Compared to other insulation materials, it is the cheapest and easiest to install. Fiberglass batt is also incredibly energy efficient, as it helps to slow the spread of hot and cold air.

Previous article
What is the first indication that a refrigerator is running low on refrigerant charge?
Next article
Can sound set off a motion detector?