The Guide on How to Insulate Under Metal Roof Panels

Talking about metal roof insulation, this thing is one of the most challenging things people do in this field. It demands and requires excellent skill and expertise, which you may only get from a reputable roofing contractor.

In this article, we will explore both the financial and technical aspects of finding the best method to insulate metal roofing.

metal roof insulation


Rroof insulation plays a crucial role in protecting your home from heat loss and condensation. Metals are excellent heat conductors, so heat transfer is inevitable when there is a temperature difference between the inside and outside of your home.

Foam board insulation, including rigid board insulation and closed cell insulation, provides a robust barrier, significantly reducing this heat transfer. By adding an insulation layer, you can prevent condensation on the metal panels, which could lead to water damage.

There are several options for metal roofs when it comes to insulation. Understanding the properties of each material, like rigid foam board or closed cell spray foam, is vital as they offer different levels of thermal resistance and moisture protection.

Read also: Why Installing Insulation Under Metal Roof Matters?

Proper insulation enhances thermal efficiency and prevents condensation, which can cause rust and deterioration of the metal panels.

Tips to install metal roof insulation

Use foam batting

Foam batting is highly recommended for pairing with roof insulation. Unlike standard insulation that can be rolled up, foam batting is installed directly on the sheath, inside and outside.

It fits perfectly under the metal roofing, reducing the hassle of installation. However, it’s crucial to install a paper liner correctly between the sheathing and the insulation to prevent mold and mildew.

Install by using staples

Using staples will allow you to install the insulation easily and quickly. You can easily install several sheets of insulation in only a few minutes without worrying about security.

Staples will also allow you to get a strong attachment without leaving a big hole, yet easy to remove when a repair is needed.

Staples for roofing
Staples for roofing

Cut panels on the roof

Before you get through with any roofing work, you need to bring up the insulation up to the roof. In order to place it quickly, you may also need to cut them precisely according to the size needed.

However, it will be much more effective if you do it when you are up on the roof. It will allow you to bring the insulation in one or two times to go up and down by using the ladder.

Leave gaps between panels

You need a gap on the roof so your room can breathe. When you find gaps or channels between the insulation pieces, it is better to leave them that way so the air can get into the house. Still, you need to make sure that the gap is not more than 1/8 inch.

The Most Popular Materials

Fiberglass Batts or Glass Mineral Wool

Exploring different roof insulation options is crucial, as some materials, like fiberglass batts or glass mineral wool, are better suited for reducing noise—a common issue with metal roofs.

The most common material used for an insulating metal roof is fiberglass batts or glass mineral wool. Both materials make a great physical barrier between the interior building and the metal roof.

The batts are located side to side on the rafter of the roof. Since they do not make a continuous barrier, air could flow through them easily, which causes heat loss in the end.

Fiberglass Batts roof Insulation
Fiberglass Batts roof Insulation

The insulation batts are not a closed system and it may need an additional vapor barrier. Unfortunately, this barrier cannot be installed directly underneath the roof. Once the water reaches the batts, it needs to be replaced.

Mineral Wool Metal Roof Insulation

This insulation type is not great for metal roofing insulation underlayment. It is still able to cause water condensation and heat loss without any option to address it. You can always make an intricate fiberglass insulation system. However, it will add cost for the roofing.

Polyurethane Spray Foam Metal Roof Insulation

To add a moisture barrier under metal roof panels, you can spray the undersides of the roof using a thick layer of spray foam insulation.

This proper installation of insulation will help you to eliminate problems that may arise when the house becomes freezing in the winter and terribly hot in the summer. Spray foam insulation is effective in sealing gaps and crevices, ensuring a complete barrier against thermal leakage.

Since this thing is something that can be sprayed, the foam will get and penetrate into the gaps and crevices to make a complete seal. As a result, any thermal leakage can be prevented from day one.

Read also: How to Insulate Under Metal Roof Panels ?

Polyurethane Spray Foam Metal Roof Insulation
Polyurethane Spray Foam

The spray can be applied on top or bottom of the metal roofing surfaces. Compared to the fiberglass batts, this insulation is much better. Financially speaking, this spray is a great option, especially when you need to renovate your roof after the application. The insulation capacity of a 10cm thickness of batts is the same as 10cm of polyurethane foam.

Radiant Barrier Spray Metal Roof Insulation

A stark reality might be happening a few decades later when it comes to energy usage. In order to reduce energy usage, you may need such an effective insulation layer to wrap your home yet prevent any unnecessary issues up there. On the other hand, if you do it properly, you can definitely reduce energy loss.

Pairing a reflective insulator with a layer of radiant barrier will help to make your home always feel comfortable without consuming a high level of energy. Also, you can save a huge amount on electricity bills.

Read also: Foam Closures for Metal Roofing

No matter if it’s an office or a home, adding roof insulation offers numerous benefits. It can be installed over existing shingles, new roof decking, or open rafters, contributing to a more energy-efficient and durable roofing system.

Radiant Barrier Spray Metal Roof Insulation
Radiant Barrier Spray Metal Roof

Adding the roof insulation can be done easily when you renovate your house. You will need to hire some well-trained roofing insulation experts to make a more energy-efficient home. Or you may also consider metal roofing over rigid insulation details even though it might be a bit pricier.

From all the roofing materials we have explained above, you are in charge of choosing which one is the best one and most suitable for your building. Other than that, some people also consider the financial thing before choosing one of them.

Lastly, proper insulation under metal roof panels is not just about energy efficiency; it also plays a significant role in the overall longevity and performance of your roofing system.”

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RoofLast is an experienced author and roofing expert. With years of practical experience in the field authored several informative articles on various aspects of roofing, including installation, maintenance, and repair