The absolute minimum for attic insulation R-values across the country is R-30, with upper recommended ranges between R-49 and R-60 for zones 1 through 3.
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. Use the JM insulation calculator to determine the recommended R-value for your project, as well as how much insulation you'll need.
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.
While loft insulation is an effective way to improve energy efficiency and reduce heating costs, over-insulating can lead to several potential issues. Firstly, over-insulation can lead to poor ventilation in the attic, which can cause moisture buildup and increase the risk of mould growth.
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.
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.
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.
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).
The recommended level for most attics is to insulate to R-38 or about 10 to 14 inches, depending on insulation type.
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.
If your attic feels drafty or your current energy costs are too high, you can easily remedy the issue by simply adding more insulation to the space. Determine the appropriate R-value recommended for attic insulation in your area then add additional layers as needed to achieve that rating.
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.
While both types provide insulation, R30 is the better option for maximizing energy savings in areas where heat loss or gain is a major concern. For example, R19 may suffice for interior walls, but R30 is more appropriate for exterior-facing attics or floors.
Drywall has a relatively low R-value — about 0.45 at ½” thickness. This is similar to building materials such as siding, concrete, dirt, face brick, particleboard, wood and single-pane glass. However, it is significantly less than materials that are commonly used for insulation.
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.
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.
Insulation is graded by its R-value—the higher the R-value, the greater the insulating power. If you live in a mild climate, your attic should have a minimum grade of R-38, or about 13–14 inches of insulation. If you live in a colder climate, R-49 is the minimum recommendation, or about 16–18 inches of insulation.
In Most Cases, Attic Insulation Does Not Need To Provide A Vapor Barrier. The good news is that blown-in insulation should not need a vapor barrier.
In hot, humid locations, it may also be advisable to construct unvented rather than vented attics to help reduce the entry of moisture-laden air into the attic. In hot, humid locations, the outside air is likely to be more humid than the inside air.
Should You Insulate the Attic Floor or Roof Deck? If you are looking for an insulation upgrade that you can see (on your energy bill) and feel (in a home that is more comfortable), we recommend insulating the attic floor, and using radiant barriers on the roof deck.
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.
For homes located in colder regions, R-38 insulation is typically recommended for attics and ceilings. Its higher thermal resistance ensures compliance with updated building codes and reduces heat loss significantly, which leads to lower heating costs during winter months.
WHAT IS THE THINNEST INSULATION AVAILABLE? 15mm Unilin(Xtratherm) is the thinnest and easiest solution to insulate hard to treat areas, especially where space is at a premium and where critical tolerances have to be achieved.