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 work in this field is facing. It demands and requires excellent skill and expertise which you may only get from a reputable roofing contractor.

In this article, we are going to explore both financial and technical aspects when it comes to looking for the best method to insulate the metal roofing.


In fact, metal roof insulation will help your home from mainly two common yet stressing things such as loss of heat and condensation. Metals are great material as a heat conductor. Whenever the temperature between outside and i1nside your house is different, the heat transfer is always there.

So, when the temperature is dropping down then water will condense on the metal panel. Putting an insulation layer could help you to stay away from this issue. There are several ways you can do to insulate the metal roof.

Read also : Why Installing Insulation Under Metal Roof Matters?

Tips to install metal roof insulation

Use foam batting

It can be touted that foam batting material is the best one to pair with metal roof insulation. It is not the normal insulation type that can be rolled up. You can always install this foam on the inside and outside of the sheath.

It can lie down perfectly under the metal roofing without having to deal with the hassle. But it is important to make sure that the paper liner is installed 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 the insulation in only a few minutes without worrying about the security.

Staples will also allow you to get a strong attachment without leaving a big hole yet easy to remove them 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 could breathe. When you found gaps or channels between the insulation pieces, it is better to leave it that way so the air could 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 Metal Roof Insulation

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
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

In order to add moisture barrier under metal roof, you can spray the undersides of the roof by using a thick layer of polyurethane spray foam. It will help you to eliminate problems that may come when the house becomes extremely cold in the winter and terribly hot in the summer.

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 since day one.

Read also : How to Insulate Under Metal Roof Panels ?

Polyurethane Spray Foam Metal Roof Insulation
Polyurethane Spray Foam Metal Roof Insulation

The spray can be basically 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 as same as 10cm of polyurethane foam.

Radiant Barrier Spray Metal Roof Insulation

A stark reality might be happening in 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 feels comfortable without consuming a high level of energy. Also, you can save a huge amount on electricity bills.

No matter it is an office or a home, a layer of metal roof insulation will give you a lot of benefits. The layer can be installed over the existing shingles, new roof decking, or simply over open rafters.

Radiant Barrier Spray Metal Roof Insulation
Radiant Barrier Spray Metal Roof Insulation

Adding the metal 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. In the end, this is anything you need to know when it comes to metal roof insulation.

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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