How does R-value work?

R-Values. An insulating material's resistance to conductive heat flow is measured or rated in terms of its thermal resistance or R-value -- the higher the R-value, the greater the insulating effectiveness. The R-value depends on the type of insulation, its thickness, and its density.

What is a good R-value?

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.

Is a low or high R-value better?

Typically, a higher insulation R rating means better climate control and better energy efficiency for your home. A higher insulation R-value usually means a higher price point as well. For every type and material of insulation, check the R-value per inch of thickness that the manufacturer has listed.

Is an R-value of 7 GOOD?

The R value is, in essence, the measurement of an insulation sheet's ability to resist heat flow. Basically, R values range from 1.5 to 7, and the higher the number is, the more effective the insulation sheet is at increasing thermal efficiency, and thereby, insulating your home.

What R-value explained?

The R-value for insulation is a way to measure how much resistance the insulation has to heat flow. The higher the R-value, the more the resistance and the better the material is at insulating a home. Generally, insulation materials with higher R-values cost more when compared to those with lower R-values.

Understanding Insulation and R-Value | Ask This Old House

How thick is R30 insulation?

8¼ ” thick, R-30C EcoTouch® Thermal Batt insulation prevents moisture damage and helps assure long roof life by providing 1" of ventilation air space between the insulation and roof deck. Easy Installation R-30C EcoTouch® Thermal Batt insulation is easy to handle and install.

How thick is R60 insulation?

The average recommended level is 17 inches of R60. How much insulation in attic for Zones 5-7? In Zone 5, the average minimum requirement for attic insulation is 11 inches of R38 fill. The average recommended level is 17 inches of R60.

Is r40 insulation good?

It is a rigid material that helps reject lots of water, adds wall racking strength as well as impact resistance. Closed-cell foam has a higher R-Value than any insulation, it ranges from 5.0 to 7.0 per inch. Regarding the thickness of the spray foam insulation, it depends on certain factors.

How thick is r50 insulation?

While conventional insulation requires a thickness of 15 inches to reach an R-value of 50, Rich-E-Board achieves the same result at just 1.5 inches thick.

Why is R19 thicker than r21?

R-21 insulation has a higher density than R-19, although it is designed to fit into the same space. It tends to be slightly thinner than R-19 because of its density. Both come in rolls and are installed the same way.

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 does R30 mean with insulation?

A wall is R-19, a roof is R-30 — what does this mean? Essentially R-value is a measure of thermal resistance, or the ability to prevent the transfer of heat. The larger the number, the harder that insulation is working at preventing heat conduction. The less heat loss, the lower your energy bills.

What insulation has highest R-value?

Vacuum insulated panels have the highest R-value, approximately R-45 (in U.S. units) per inch; aerogel has the next highest R-value (about R-10 to R-30 per inch), followed by polyurethane (PUR) and phenolic foam insulations with R-7 per inch.

Does insulation lose R-value over time?

Yes. Cellulose insulation does lose its R-value when it is compressed. The amount of loss depends on how much insulation is decompressed but typically ranges anywhere from 15% to 20% of its initial value.

What R-value is blown in insulation?

Blown-in fiberglass has an R-value of 2.2 to 2.7 per inch. Batts. Fiberglass batts and rolls are ideal for placement between framing during construction in floors, walls, attics, and ceilings.

How many inches of insulation do I need for an R40?

To achieve R-40, we install 12” of cellulose insulation. To achieve R-50, we install 15” of cellulose insulation.

What is the highest R-value for a 2x4 wall?

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.

Can you have too much insulation in your 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 blown-in insulation better than rolls?

The Differences Between Blown-in and Rolled Insulation

In terms of R-value, they tend to be equal, although you can choose rolled insulation with varying R-values depending on your needs and your budget. The lower the R-value is, the less effective it will be as insulation – although it will be cheaper as well.

Is R60 too much insulation?

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.