## What is the R-value of 2lb closed cell foam?

The denser the foam, the more R-value per inch. On average, one inch of 2-lb. closed cell foam that has fully cured will perform at a **R-6.8**. That means a 2×6 wall cavity filled with five inches of foam will achieve an impressive R-34, almost double the R-value you could achieve with fiberglass.

## What is the R factor of closed cell foam?

R-7 per inch

Closed cell spray foam has an R-value of **R-7 per inch**. In comparison, open cell spray foam has an R-value of R-3.8 per inch.

## What is the highest R-value for spray foam insulation?

Spray Foam

The foam (usually polyurethane) is sprayed to fill cracks and gaps in the attic to form a hermetically sealed barrier. **Spray foam provides the highest R-value** – while open cell spray foam has about an R-value of 2.2 to 3.5 per inch, closed cell spray foam has about 6-7 per inch.

## How thick should closed cell insulation be?

Closed cell spray foam should be **4- to 5- inches on the ceiling and 2- to 3-inches in the walls**. This might come as a surprise to you, but honestly, this is all the spray foam it takes to get the biggest bang for your buck with the air seal and thermal resistance needed for certain areas of the home.

## What is the R-value of 2 inches of spray foam closed cell?

R-Value In 2 Inches Of Spray Foam

The R-value ranges from **R-3.5 to R-3.6 per inch**. The filling of a 2×4 cavity yields about an R-13.

## HOW MUCH DOES closed cell foam expand?

approx. 1 inch thick

Closed cell foam expands to **approx.** **1 inch thick when applied**. Open cell foam expands to a whopping 3 inches thick. It’s this ability to expand that allows the foam to completely fill every crevasse and open space it encounters, providing a superior air seal that far outperforms other insulation types.

## What is the R-value of closed cell spray foam in a 2×4 wall?

R-6.5-7 per inch

The R-value of closed-cell foam is **R-6.5-7 per inch**. Contractors often use it to insulate under slabs, ceilings, walls, and roofs. It performs better than other insulation types.

## Does closed cell foam need a vapor barrier?

Closed-cell spray foam insulation, on the other hand, is completely moisture-resistant. Because it creates a moisture barrier on its own, **there is no need to install a separate vapor barrier as long as a sufficient quantity of insulation has been implemented**—typically around 1.5 inches thick.

## What is a good R-value for insulation?

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. See the Department of Energy’s (DOE) ranges for recommended levels of insulation below.

## What is the R-value of 4 inches of spray foam?

Spray Foam Insulation R-Value

Open cell spray foam insulation is **R-3.6 to R-3.9 per inch**. This R-Value is normal for open cell spray foam.

## How thick can you spray closed cell spray foam?

The ASTM E84 tests for most spray polyurethane foams limit the maximum installed thickness of foams to **4 inches or less**. The ASTM E84 tests for some SPF products limit installations to a maximum of only 2 inches.

## How do I calculate spray foam insulation?

To calculate how much foam you require to complete a job, **multiply the square feet of area by the thickness of the foam to be sprayed**. If the area is 1000 ft2 and you want to spray the foam 2½” thick, then multiply 1000 ft2 x 2½” which equals 2500 bf of foam required to spray the area.

## What R-value is 3 inches of spray foam?

The R-value of open cell spray foam is about **3.5 per inch**, although the R-value can be different depending on the product. Open cell spray foam has a low density and is many times applied in interior walls and areas that are hard to reach in a home.

## Where should you not use spray foam insulation?

**When NOT to Use Spray Foam Insulation**

- For areas that are too close to electrical boxes:
- For areas too close to ceiling light boxes:
- Open-cell spray foam on your roof:
- For closed-cavity spaces:
- If you have a history of skin, respiratory, or asthma problems:

## What is the thinnest insulation with highest R-value?

Aerogel insulation

**Aerogel insulation** offers the highest R-value of any insulating material at less weight and thickness—ideal for construction, refineries, pipelines, and thin-gap thermal barriers.

## What is the highest R-value insulation for a 2×4 wall?

Fiberglass and rock wool batts—2×4 walls can hold **R-13 or R-15** batts; 2×6 walls can have R-19 or R-21 products.

## What insulation has the most R-value per inch?

rigid foam panels

Among insulation types, **rigid foam panels** have the highest R-value per inch.

## What R-value should attic insulation have?

R-Value is a measure of insulation’s ability to resist heat flow. 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.

## 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 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.