View All Posts

Metal Building Insulation: The 5 Best Options
Lauren Risotto

By: Lauren Risotto on January 13th, 2021

Print/Save as PDF

Metal Building Insulation: The 5 Best Options

Metal Roof Installation | Metal Siding

Insulation is an essential accessory to a metal building to help keep energy costs lower. Proper insulation will keep a structure warmer in the winter and cooler in the summer so that less cooling and heating system usage is necessary. Insulation is also essential to keep your structure up to building code, as the necessary R-value for the insulation needed is always specified.

Insulation comes in many different forms and is certainly not a one size fits all product. At Western States Metal Roofing, we’ve worked with thousands of contractors that have trusted us to supply the materials for their metal roofing and siding projects. We understand the importance of quality materials and choosing which products are best for each individual project. We want to make sure you understand your insulation options so you can choose which one is best for you.

In this article, we go over the top 5 insulations to consider for a metal roof or metal siding and their respective R-values.

What Is The R-Value Of Insulation?

An R-value, or the rating given to insulation that determines how well it can prevent heat from entering or leaving the building, determines the quality of the insulation. 

Contributing factors to R-values are:

  • Type of Insulation
  • Density
  • Thickness 

The higher the R-value, the better the quality of insulation. When we discuss insulation options below, we have ranked them from highest to lowest R-value.

How Much Insulation Does My Metal Building Need?

The amount of insulation needed will depend on:

  • Climate
  • Type of heating/cooling system
  • Area of the building that is being insulated

The more insulation that is installed will increase the R-value, which also increases the effectiveness of the insulation. 

There are minimum R-value requirements for non-residential buildings. These requirements vary based on location. Be sure to consult your local building code to verify the minimum R-value needed for your state.

The 5 Best Metal Roofing And Siding Insulation Options

  1. Spray Foam
  2. Rigid Board
  3. Batt and Blanket
  4. Loose-fill
  5. Foil Bubble

1.Spray Foam Insulation For Metal Buildings

Spray foam insulation is a two-part liquid insulation material that foams to insulate where it is applied. It comes in both open-cell and closed-cell varieties and is a type of insulation that never sags or loses its shape over time. The insulation creates an air seal for cracks and gaps as well as large open areas like attics or pole barns.

Open-cell vs. Closed-cell Spray Foam

Spray foam insulation comes in both open-cell and closed-cell foam. The open-cell is a more flexible material while the closed- cell is more stable and doesn’t allow moisture to penetrate through the insulation. While both successfully create an air seal, there are differences that could make one a better option for you than the other. 


Open-cell spray foam: 

  • Expands up to 100 times its size to fill in everywhere it is sprayed.
  • More affordable compared to closed-cell spray foam.
  • More commonly used for residential projects.
  • Does not stop water from passing through.


Closed-cell spray foam:

  • Does not have a high expansion rate, is a good choice for smaller areas.
  • Stronger and more durable (higher R-value)  than open-cell foam.
  • Can be left exposed without the worry of foam being damaged. 
  • Water can not pass through closed cell spray foam.

What Is The R-Value Of Spray Foam Insulation?

Open-cell spray foam insulation has an R-value of R-3.0 -R-4.0 per inch.


Closed-cell spray foam insulation has an R-value of R-6.0- R-8.0 per inch.


When Is It Best To Use Open- Cell Spray Foam?

  • Filling in a large area
  • For use around obstructions
  • When looking for the more affordable insulation (compared to closed-cell foam)

When Is It Best To Use Closed-cell Spray Foam?

  • Smaller areas
  • For extra strength and durability
  • Irregularly shaped areas

2. Rigid Board Insulation For Metal Buildings

Rigid board insulation comes in dense sheets that are very durable and resistant to natural elements. The chemical structure of rigid boards is considered to be “closed-cell” as opposed to “open-cell”. Closed-cell insulation generally has greater strength and durability due to its structure and does not allow moisture to pass through it.


Rigid Board insulation can be made from: 

  • fiberglass
  • polyurethane 
  • polystyrene

What Is The R-Value Of Rigid Board Insulation?

The R-value of Rigid Board ranges from R-4.0 – R-8.0 per inch.


When Is It Best To Use Rigid Board Insulation?

  • Flat roofs, walls, foundations, attics
  • When heavy insulation is necessary
  • For extra water resistance

3.Batt and Blanket Insulation For Metal Buildings

Batt and blanket insulation is the most common type of insulation used in the United States largely because it is the most affordable type of insulation. This makes them a good choice for metal projects that are on a small budget. It is often fitted between joists, studs, and beams. 

Batt insulation comes in pre-cut rectangular pieces while blanket insulation can be cut to fit the space you need to fill. Since blanket insulation is in roll form, it’s convenient when used in open areas without many obstructions so that it does not need to be cut.

Blanket insulation can be made from: 

  • Fiberglass
  • Mineral wool
  • Plastic fibers
  • Natural fibers

What Is The R-Value Of Batt And Blanket Insulation?

Blanket insulation has an approximate R-value of R-2.9 to R-3.8 per inch of thickness.

When Is It Best To Use Batt And Blanket Insulation?

  • When looking for the most affordable insulation
  • Open, unobstructed areas or fitting between joists, studs, and beams.

4.Loose-fill Insulation For Metal Buildings

Loose-fill insulation is made up of small particles that are blown-in to the desired area with an industrial blower. Because of its installation process, loose-fill is also referred to as “blown-in” insulation. 

Loose-fill can be used for tight spaces and any on any type of roof shape. 

Loose-fill insulation can be made from: 

  • cellulose
  • fiberglass

What Is The R-Value Of Loose-fill Insulation?

The R-value of loose-fill insulation ranges between R-2.2- R-3.8 per inch of thickness. The range varies based on the material of the loose-fill

For example, loose-fill fiberglass has an R-value of R-2.2 to 2.7 per inch, while loose-fill cellulose is R-3.2 to R-3.8 per inch.


When Is It Best To Use Loose-fill Insulation?

  • When insulation is needed in tight areas
  • Adding insulation to already finished areas
  • Easy and fast installation

5.Foil Bubble Insulation For Metal Buildings

Foil Bubble, or reflective foil, insulation is a lightweight and waterproof material that helps reflect radiant heat transfer in metal buildings. It’s made from enclosed bubble layers and is sealed with multiple layers of polyester. 


What Is The R-Value Of Foil Bubble Insulation? 

The R-value of bubble insulation is between R-1.0- R-1.3 and are usually ⅜ of an inch thick or less.


When Is It Best To Use Foil Bubble Insulation?

  • To prevent downward heat flow
  • When obstructions are present
  • For DIY or easy installation

Choosing The Right Insulation For Your Metal Building

Every building is unique and the best insulation to use will vary from project to project. 

When deciding, consider factors such as:

  • Budget
  • R-value requirements
  • Climate 

When you’re ready to get started on your metal building project, we’ll help you decide which metal panel to use. 

For a detailed overview of the different metal panel options, we recommend reading:

The 5 Best Metal Siding And Wall Panels. And What You’ll Pay.

Residential Metal Roofing Styles And Colors


Metal Roofing Learning Cener


Discover the differences between exposed and concealed fastener panels and which is best for you to use by watching this video:

About Lauren Risotto

Lauren is the Content Manager at Western States Metal Roofing and provides insight on content creation and product promotions.