How Thick is R-38 Insulation

When it comes to insulation, understanding the R-value is essential to making the right choices for your home. But what exactly is R-38 insulation, and how thick is it? In this comprehensive blog post, we’ll explore the ins and outs of R-38 insulation, its thickness, and why it’s crucial in maintaining an energy-efficient home. Get ready to dive deep into the insulation world and make informed decisions for your living spaces!

What is R-Value and Why is it Important?

Before we delve into R-38 insulation, let’s take a moment to understand the concept of R-value. The R-value measures an insulation material’s ability to resist heat flow. Higher R-values equate to better insulation, reduced energy costs, and increased comfort within your home. Proper R-value insulation is crucial to ensure optimal energy efficiency and maintain comfortable indoor temperatures year-round.

Introducing R-38 Insulation

R-38 insulation is a commonly recommended insulation level for attics and other areas of your home where heat transfer is significant. It is trendy in regions with extreme temperature fluctuations, as it provides substantial thermal resistance to keep your home cozy in the winter and cool in the summer. It’s important to note that R-38 is not a specific product but rather a rating indicating the insulating capacity of the material. Various insulation materials such as fiberglass, cellulose, or spray foam can achieve an R-38 rating.

The thickness of R-38 Insulation

The thickness of R-38 insulation will vary depending on the type of material used. Here’s a breakdown of the approximate thicknesses for different R-38 insulation materials:

  1. Fibreglass batts: This is the most common type of insulation in residential construction. R-38 fiberglass batts typically measure between 12 and 13 inches in thickness.
  2. Cellulose: Made from recycled paper products, cellulose insulation, is an eco-friendly option. To achieve an R-38 rating, cellulose insulation must be about 10 to 12 inches thick.
  3. Spray foam: Closed-cell spray foam is a highly effective insulation option, and its R-value per inch is significantly higher than other materials. To achieve R-38, closed-cell spray foam must be about 5.5 to 6.5 inches thick.

Remember, these thicknesses are approximate and can vary depending on the product and manufacturer. Always refer to the product specifications for accurate measurements.

Why Choose R-38 Insulation?

There are several reasons to consider R-38 insulation for your home:

  1. Energy efficiency: R-38 insulation provides substantial thermal resistance, helping you maintain comfortable indoor temperatures while reducing energy consumption. This translates to lower utility bills and a reduced carbon footprint.
  2. Cost-effectiveness: While the upfront cost of R-38 insulation may be higher than lower R-value options, the long-term savings on energy bills make it a worthwhile investment.
  3. Noise reduction: A higher R-value can also help with soundproofing, reducing the transmission of noise from outside and between different rooms of your home.
  4. Compliance with building codes: Many building codes and energy-efficiency programs require a minimum R-value for new construction or renovation projects. R-38 insulation often meets or exceeds these requirements, ensuring your home is compliant.


The thickness of R-38 insulation varies depending on the material used, but it typically ranges from 5.5 inches (for closed-cell spray foam) to 13 inches (for fiberglass batts). This level of insulation is ideal for maintaining energy efficiency and comfort in your home, particularly in regions with extreme temperature fluctuations.