Metal Building Energy Efficiency: How to Insulate a Metal Building


Insulation is one of the most critical aspects of a metal building. However, with numerous different kinds of insulation, it is no longer suitable to choose the traditional insulation method without researching which kind would best benefit the building. Choosing the correct insulation is a proactive step in metal roof installation. It can lengthen the roof’s lifespan and decrease the risk of damage. Here, we are discussing everything there is to know about metal building insulation. We have you covered from how to insulate metal buildings to the different types of insulation. 

What is Insulation?

The thermal layer of material that acts as a barrier is known as insulation. It can be added under the roof panels and walls to reduce heat loss or gain. Air and moisture can travel through any cracks or openings in a building. Adding insulation eliminates the risk of damage from condensation or air leakage. 

Why is Insulation Important in Metal Buildings?

Insulation maximizes energy efficiency, ensuring that a building remains within a set temperature and is not swayed by the outside temperature. Insulation not only helps regulate internal temperature, it also supports the overall structure of the building. When the right insulation is installed, it can increase the building’s lifespan by advancing its structural strength. It can act as a sound-absorbing material that will limit outside noise. On top of that, it can help eliminate condensation so water damage does not become high-risk. That can save the clients money in the long run because water damage will not be common. 

Does a Metal Roof Need Insulation?

Insulation is one of the most important components to keep a building or home energy efficient and reduce noise. We recommend that all metal roofing systems have insulation. Even small metal sheds can benefit from insulation. Insulation is required to keep the electricity bill low while maintaining a comfortable temperature. 

Choosing the right insulation for your project can be overwhelming. With numerous insulation options and differing roofing designs, one type of insulation will be the best fit for some buildings. Understanding how to insulate metal buildings and the difference between each type of installation is crucial to help you make the right choice. 

Types of Metal Building Roof Insulation

Wide Batt

Batt insulation comes in flat pieces usually. It is made of fiberglass or mineral wool pre-cut into flat pieces. Some batt insulation comes with a foil or paper (kraft) facing, and some come with no facing. Batt insulation is an inexpensive way to insulate your buildings. While the term wide is used, you can have different widths and thicknesses of your insulation. The most common thickness is roughly 6 and 7 inches but it can vary based on needs.

Single Layer Faced Fiberglass Blanket 

The traditional insulation method is loved by many for its low cost, easy installation, and appealing look. However, it has yet to meet conditioned space requirements for most of the United States. It goes on top of and perpendicular to the roof purlins when installed. 

Sag and Bag Two-Layer System

While this option can be a low-cost solution to a high R-Value roof, it does not meet most energy codes. The roof purlins can cause inconsistencies with the thermal bridging, resulting in poorly performing insulation. 

Fabric Liner Multilayer System

This has become one of the most popular insulation options due to its many benefits. It is installed below the roof purlins and can serve as a vapor barrier. It is compatible with numerous roof designs and has a reputation for meeting building energy requirements. 

Rigid Board Insulation

For a continuous insulation system, rigid board insulation may be a good fit. This insulation is sandwiched between the roof purlins and panels. This easy-to-install option can reduce thermal bridging. 

Reflective Insulation

If a building or room has a large amount of natural light, this niche option could be a good fit. Reflective insulation is made up of high-grade aluminum to increase heat reflection. This will repel heat away from the home when it is unwanted. Vinyl facing can be an addition that will increase durability. 

Spray Foam Insulation

Screw-down roof systems are compatible with spray foam insulation. However, avoid using this insulation if you are planning a standing seam metal roof installation. As the insulation settles into place, it will become rigid, making it impossible to expand and contract with the standing seam roof. 

Frequently Asked Questions About Insulation

1. How Do I Stop My Metal Roof From Sweating?

When too much humidity condenses on the inside of your panels, it can create moisture, known as sweating, on the exterior of your panels. To prevent sweating from happening, install underlayment between the panels and the roof deck. Ensuring proper ventilation is another way to prevent sweating on a metal roof. 

2. Do I Need a Vapor Barrier Under a Metal Roof?

Vapor barriers can aid in stopping sweating when condensation forms under the metal panels; adding a vapor barrier can prevent air from moving through the insulation and onto the roof’s exterior. When this happens, condensation will form on the roof’s panels. 

3. Do You Need Plywood Under a Metal Roof?

Adding plywood under a metal roof can be a great practice. However, it is not a required step. When you add plywood under a roof, it will impact the insulation long term. When the roof needs to be replaced years later, the plywood will serve as a barrier and protect the insulation during the project. 

4. How Do You Insulate Condensation on a Metal Roof?

When condensation forms under your roof’s panels, it can ultimately lead to water and mold damage. When insulation is installed correctly from the beginning, it can ensure that the panels never reach the point where they begin to create dew. Vinyl-backed fiberglass insulation prevents humid air from reaching the metal roof and can greatly help eliminate condensation. 

Investing in Your Roof

When a roof is properly insulated, it can increase the quality of the building’s living and work conditions. By preventing water damage from the beginning, you can save your clients future headaches, stress, and money on fixing unwanted problems. 

No matter what type of insulation you choose for your next project, it will require numerous tools and materials to complete the job successfully. Be prepared for any step in the metal roof installation process by downloading our Builders Materials Checklist for Contractors

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