What is the difference between R19 and R38?

Author: Miss Mollie Grant PhD  |  Last update: Wednesday, May 7, 2025

The various performance levels, R-19, R-30 and R-38 is all made from the same insulation material, only the thickness of the insulation differs in order to achieve different R-values and performance.

Is R19 insulation good enough for an attic?

Yes, R19 insulation can be used in an attic, depending on the specific requirements and climate conditions.

What is R-38 insulation good for?

Cold Climates (Zones 4-8)

In these zones, where winters are severe, R-38 insulation is recommended for attics and ceilings to maintain indoor warmth and minimize energy loss. The higher thermal resistance of R-38 provides significant energy savings and improved indoor comfort during colder months.

What is R19 insulation used for?

R19 Insulation offers superior thermal insulation compared to R13. With a typical thickness of 6.25 inches, R19 fiberglass is designed for use in 2x6 wall cavities, making them suitable for colder climates where higher thermal resistance is necessary.

Is R19 good for garage ceiling?

R19 is standard for 6'' walls. R30 or R38 is standard for ceilings.

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What is the best R-value for a garage ceiling?

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.

Which is better, R19 or R30 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.

Is R19 worth it over R13?

R-value is used to judge thermal insulation performance and the higher the number, the better the product's insulating ability. So R19 has better insulating ability than R13. Now R-Value ranges widely across products and home applications.

Can I put R19 in a 2x4 wall?

The DOE Insulation Fact Sheet (DOE/CE-0180) can be ordered from the Energy Efficiency and Renewable Energy Clearinghouse or accessed from the Internet at www.ornl.gov/ roofs+walls. Fiberglass and rock wool batts—2x4 walls can hold R-13 or R-15 batts; 2x6 walls can have R-19 or R-21 products.

What is the difference between R19 and R38 insulation?

The various performance levels, R-19, R-30 and R-38 is all made from the same insulation material, only the thickness of the insulation differs in order to achieve different R-values and performance.

Which insulation is best for a ceiling?

When it comes to insulating ceilings, attics, walls, and crawlspaces, homeowners and builders often choose fiberglass batts. Besides being cost-effective, they prevent heat from passing through walls, ceilings, and floors. Generally, fiberglass batts come in 2*4 or 2*6, but you can cut them down if necessary.

What does R38 mean?

R38. Definition. Stop Payment on Source Document.

Can you double up R19 insulation?

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.

Which is better, R19 or R21 insulation?

R-21 insulation achieves its superior performance with minimal difference in thickness compared to R-19, to make it ideal for applications where space is limited.

What is the best R-value for an attic?

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 R38 insulation worth it?

R38 insulation offers superior thermal resistance and energy efficiency compared to lower R-value options. It's designed to provide optimal protection against heat transfer in various climates, making it an excellent choice for homeowners seeking maximum energy savings.

Should attic insulation be faced or unfaced?

You can use faced or unfaced batting when installing between the roof rafters of finished attic spaces. When using paper or plastic batting insulation, that moisture barrier should face outward toward the attic space. Even if the attic space is unheated, it's typically warmer than the outside air in winter.

How thick is R19?

R19 is 6.5″ thick whereas R21 is 5.5″ thick. Thinner by one inch and yet 2 points higher in R value. The common explanation as to why this is so, is that the R21 insulation is said to be “more dense”.

Can you have too high of an R-value insulation?

The optimal R-value for most homes is 30, but you can go as high as 38 if you live in a tropical climate. Anything higher than 38 indicates an over-insulated space.

How thick is R38 insulation?

Thickness of R-38 Insulation

An R-38 fiberglass batt should be approximately 12 inches thick, while the thickness of cellulose insulation of a finished, fitted product will larger.

What is R13 insulation good for?

Known for its sound reduction and easy installation, R-13 batts serve as a thermal barrier, keeping your home comfortable by resisting heat flow. Perfect for modern framing, they ensure minimal obstruction from electrical or plumbing work.

Is it okay to use R19 insulation in attics?

For example, homeowners in the southern United States can begin insulating their attic using materials that have R-values in the R30 to R60 range and R13 to R19 insulation ratings for the floors. Attic insulation should be R49-R60, while floor insulation should be R25-R30 for those in the north of the United States.

Should you use faced or unfaced insulation in a crawl space?

Faced insulation is ideal for spaces that have no existing insulation, such as exterior walls, attic ceilings, crawl spaces, and exterior basement walls. Please note that the proper way to install it is to have it installed facing outward or towards the person installing it.

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%!

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