Rigid Foam Insulation under Metal Roof: Which Is the Best Roof Insulation?

Many homeowners have been considering installing rigid foam insulation under metal roof for better results. A rigid foam board has been one of the many options for insulation, and it happens for a good reason.

You probably think that the rigid form will make it difficult for the installation, but unless you are going to do it by yourself, you simply leave it to the pro to do the arrangement. The combination of a sturdy metal roof and the right insulation can affect your house.

Not only it will affect the aesthetic appeal, but also the energy usage and management. So, what should you know about it?

Metal Roof and Proper Insulation

So, what’s the deal with a metal roof and proper insulation? You see, the popularity of metal roofs has increased lately. The metal roof is beautiful, and it has its aesthetic appeal. It’s also durable, which means that it can last longer than other roofing types, such as asphalt shingles.

Read also: Applying Burnished Slate Metal Roof

rigid foam insulation under metal roof

When you combine it with insulation, it will boost energy efficiency, affecting your monthly bills and comfort.

Most roofing structures need to be insulated, regardless of the type or material. With insulation, you can improve not only energy conservation but you can also reduce noise pollution. Want to make your house cozy, quiet, and warm? Then insulate your roof.  

Read also: Shed Roof Ridge Flashing Installation Guide

Can You Put Insulation under a Metal Roof?

Definitely yes. Even with the already existing roof, you can still install the insulation properly. This is one of the reasons why you need to hire a professional service. Roofing is a complex matter that needs professional care.

Not everyone can do it. And it’s certainly not the type of DIY project that you can do on your own. Want to get the best result? Hire a professional and certified expert to get the work done.

What Is the Best Insulation to Use Under Metal Roof?

Sure, you can use rigid foam insulation under a metal roof, but there are other options available.

  • Fiberglass Batts

The material is similar to the one used in glassware. This type of insulation is cheap and easy. It’s the cheapest option for roof insulation. The material is also versatile and flexible. Feel free to cut it the way you want it to. Not only you can place it under the roof panels, but you can install it on the existing surface of the roof.

The only con is that the material isn’t exactly safe. The microscopic glass can hurt your eyes, lungs, and hands during the installation. That’s why you should leave it to the pro because they know what to do. They wear protective gear during the installation process.

The price depends on the R-value. If it has an R-value of 11, the cost may range from $0.12 to around $0.16 a square foot. If it has 38 R-value, it may range between $0.55 and $0.60 a square foot.

  • Rigid Board

This type is handy for thermal resistance, especially for walls, roofs, and foundations. This insulation is available in panels or sheets, and the sizes are various. The panel or sheet is made from polyurethane or polystyrene.

This one can provide maximum thermal resistance when it’s installed properly. It means that you should seal the joints and fit the sheets tightly together. It’s also handy in reducing air leakage.

The only downside is that it must be installed properly. Otherwise, it can be easily damaged by the UV rays. If you don’t fit the sheets tightly, it still results in air filtration or air leakage. In terms of price, the price may range from $3.95 to around $7.20. it depends on the quality.

  • Spray Foam

This insulation type must be mixed with water, and it needs a special machine for the application. It’s likable because not only it’s one of the most effective choices for the metal roof, but it’s also easy to work with – for those who are experienced with this method.

With it, you don’t have to re-proof to install the insulation. It’s also the best option for areas with odd or awkward shapes. It’s also effective enough to prevent insect or rodent infestation along with condensation buildup.

The only downside is the application. As it was mentioned before, this can only be done by a professional, considering the tools and equipment. This insulation costs between $1 and $1.50 a board foot for the closed-cell spray foam. If you go with the open cell spray foam, it’s from $0.44 to $0.65 a board foot.

Read also: How much is Blown In Insulation Cost ?


It’s up to you to choose which insulation for your metal roof. If you are adamant about the rigid foam insulation under metal roof, that’s fine, but you should know that you have different options.

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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