What is the R-value for roof insulation?

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.

What is the ideal R-value for attic insulation?

Attics. 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.

What type of insulation should I use for roof?

One of the most common and effective ways to insulate your roof is with polyurethane spray foam. This spray-applied plastic is known to be highly effective for sealing any cracks as well as resisting wind and heat. The foam is applied to the underside of your roof deck and directly onto the slates and tiles.

Can you use R 13 insulation in the ceiling?

R13 batt insulation is typically used to attenuate sound in interior wall cavities. It is akin to a large blanket, designed specifically to fill a wall, floor, or ceiling cavity.

Is R30 insulation good for attic?

The average recommended level is 14 inches of R49. In Zone 2, the average minimum requirement for attic insulation is 9 inches of R30 fill. The average recommended level is 17 inches of R60. In Zone 3, the average minimum requirement for attic insulation is 9 inches of R30 fill.

Understanding Insulation and R-Value | Ask This Old House

Can I have too much insulation in my attic?

It's possible to over-insulate an attic as too much will cause moisture buildup and eventually result in mold. Eventually, adding more insulation leads to diminishing returns in trapping heat as well.

Is there a big difference between R13 and R19 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.

What is the difference between R-13 and R19 insulation?

Although the U.S. Department of Energy rates R-13 insulation as "good" for use in walls in southern areas of the country, it rates R-19 insulation higher, designating it as "great." That is because R-19 insulation provides more thermal insulation than R-13 does.

Is R19 good for garage ceiling?

If my garage ceiling wasn't insulated, all that heat would rise to my bedroom and my AC bill would be much higher. R-19 insulation is suitable for floors/ceilings in most homes, unless it's the highest ceiling in a house.

What is a good R-value for a roof?

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.

Should you insulate the underside of your roof?

In order to avoid damage to the roof deck, you should insulate ceilings to create an air barrier between the living space and an unfinished attic or airspace underneath the roof deck.

How do you calculate the R-value of a roof?

To calculate the R-value, you simply add together the total thickness (in inches) of each insulating material within your roofing system: “For each different material, multiply the thickness by the standard R-value per inch for that material.

Is R60 attic insulation worth it?

Recommended R-Value Varies by State

You need exactly as much as the area you live in determines. Here, where temps get pretty hot for much of the year, attics should have from R30 to R60 (average is R38). Those living up north want anything from R49 to R60. This helps insulate against the extreme cold weather.

What type of insulation should I use in my attic?

Fiberglass, cotton, and mineral wool can all work as loose-fill 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.

How often should attic insulation be replaced?

As a general rule, insulation should be replaced or retrofitted every 15 to 20 years. However, it may need replacing or retrofitting sooner depending on the type of insulation installed, the R rating of the original insulation, compression and movement over time, and whether any damage has occurred.

What is r21 insulation used for?

The higher the R-value, the more effective the insulation is. Both R-19 and R-21 insulation are commonly used to insulate walls of homes framed with 2-by-6 lumber, and each are recommended by U.S. Department of Energy to efficiently insulate new construction.

What is R 15 insulation used for?

Maximum R-Value at Lower Costs R-15 EcoTouch® insulation is designed to allow the use of a thinner exterior sheathing while still easily achieving high recommended R-values for exterior walls.

How do you calculate insulation for a ceiling?

Multiply the wall's length by the wall's height and don't forget to write down the spacing of the studs so you can then determine what type of the insulation will be purchased. You will need this as insulation normally comes in precut lengths or standard rolls designed to fit exactly into between studs.

What is r20 insulation used for?

Description. Use this Johns Manville fibreglass insulation to cover your walls and ceilings in basements, crawl spaces and attics. Offering a thermal resistance of R-20, this 19 in x 48 in insulation batt provides moisture control in exterior walls.

Is r13 insulation good for garage walls?

If your exterior walls are constructed from 2-by-4 inch studs, the most insulation that can go into the wall while retaining its R-value is R-13 or R-15 as these are both made to fit a cavity 3 1/2 inches deep.

Does doubling the insulation increase the R-value?

ABOUT INSULATION

The thermal barrier of a home should consist of a continuous layer of insulation on all sides—including the lowest floor, the exterior walls, and the ceiling or roof. Doubling the thickness of insulation will double the insulation's R-value, cutting heat loss in half.