Some people overlook installing roof insulation when building or reconstructing houses. They often choose the best material for their roof and settle on using only that to protect their homes. However, there are several benefits to having roof insulation, especially for metal roofs. Suppose you’ve decided to have roof insulation. In that case, there are several aspects to consider, such as choosing the best option and understanding the process of installing this on a roof. 

Before doing a DIY project or asking professionals to install insulation, it’s best to consider different factors to ensure that you’re getting the best option and following the necessary process for your house. Here’s a guide to help you install your metal roof insulation. 

Why insulate metal roofs

Before going into your insulation options, you may wonder if it’s truly worth all the trouble. The answer is yes – it’s highly recommended to insulate your roof. Metal roofs are not protected on their own, making your house lose beneficial hot or cold air. Proper insulation helps you make your home more energy efficient by helping you stay warm during cold seasons and cool during hot seasons. 

Installing the correct and effective insulation for your metal roof also protects you from elements, including rain, snow, and intense heat. In addition, insulation helps reduce noise pollution. It’s known that having a metal roof means noisy houses under heavy rain and fierce wind. Having insulation for metal roofs reduces this noise. Moreover, increased sturdiness from insulation can also help you pass a commercial property inspection by eliminating potential roofing issues. 

What to consider before insulating a metal roof

As you can see, insulating comes with several benefits. But before you can start with the process and buying the insulation materials, there are some factors that you should consider first. Understanding these can help you choose the best type of insulation and how you’re going forward with your preferred insulation methods.

Roof condition

The roof itself will affect how you would insulate and what kind of insulation would work best for your home. The best insulation material will depend on whether you’re working on an existing roof or if you’re just about to install the insulation before constructing or reconstructing a new roof. You should also look at the roof’s conditions. For example, if some gaps or leaks allow air to escape, the insulation might just be ineffective, so it’s best to make any necessary repairs first. 

Insulating ability

The next factor you should consider is which correct insulation material best suits your insulation needs. Different insulation materials have varying R-values (the resistance of heat flow), so depending on your location and climate, you should choose the best material that has the thermal resistance that works best for you. If you’re unsure about the minimum R-value that works for your house, it’s best to ask insulation suppliers or professionals. 


Another factor that you should consider is your budget. Some insulation types are more expensive than others. Knowing how much you’re willing to spend on insulation when constructing or reconstructing your house can help you determine which material is best for you, whether you should look for an affordable insulation material or go for something more expensive.

Experience and equipment

Lastly, if you’re wondering whether you should do the insulating on your own or if you should hire professionals to get the job done, you should consider your own experience and equipment. Depending on the material, insulating can both be difficult and dangerous if you’re not knowledgeable about the process. If you’re not confident about insulating on your own or do not have the necessary equipment, hiring professionals is best. 

Read more: How to hire a roofing contractor

Best metal roofing and siding insulation options

Now that you’ve considered the different factors, you should then look into the best materials for insulating your house’s roof. Here are some of the best metal roof insulation options:

Spray Foam Insulation

One of the best insulation options for metal roofs is spray foam. Spray foam insulation comprises a two-part liquid insulation material that foams to insulate the area where it is administered. It’s considered the best option for metal roofs because it is easy to use. 

It can be used on both old and new roofs, and because of its material, it does not look misshapen over time. It’s also excellent insulation to use as a seal for covering cracks or spaces. However, with these benefits, the main disadvantage is that it’s pretty difficult and dangerous to apply this on your own, so it would be best to have professionals do it for you, which can be expensive in some cases. 

There are two options for spray foam insulation: open-cell and closed-cell insulation. The former is more flexible and can easily expand wherever it’s used. It’s also more affordable compared to the closed-cell spray foam. On the other hand, the closed-cell foam is stronger and doesn’t allow water to pass through it. However, it doesn’t expand as much as open-cell spray foam, so it’s better to use this type in smaller areas. 

Rigid Board Insulation

Another option you can choose is rigid board insulation, also known as foam board insulation or rigid foam insulation. These are durable and resistant sheets or panels made from polystyrene, polyurethane, or polyiso. This type of insulation is preferred mainly for its higher R-value, allowing it to provide more insulation for roofs. Its material is also thicker and denser, making it more air and water-resistant.  

However, the main downside is how perfectly fit these boards must be installed. You should ensure that the rigid foam insulation is fitted and installed correctly. If not, UV rays can damage the material, and air can easily infiltrate it. 

Fiberglass Batts

This insulation material uses thread-like glass that is interwoven together with other materials. Many people favor it because it’s one of the most affordable insulation options, and it’s easier to use for roof insulation. Fiberglass batt insulation is also versatile, making it easy for you to cut and shape it to fit your roof structure and needs. Additionally, it’s pretty environmentally friendly as the fiberglass batts are usually made from recycled glass. It’s also resilient enough to prevent collapse and offers fire resistance. 

The main negative concern about fiberglass insulation is it’s unsafe to use and install. In addition, the bits of glass can be damaging to you, so it’s essential to wear the appropriate PPE. Better yet, it’s better to look for professionals to install them for you if you don’t have the equipment and experience yet. 

How to insulate a metal roof

Once you’ve considered the factors and chosen what kind of insulation you will put in place, it’s time to get to the insulation process. The process is quite different between insulating a new and existing roof. Fiberglass batts and spray foam insulation are both more appropriate for insulating an existing roof, while rigid foam insulation is best for new roofs. 

New roof

Rigid or foam boards are best used for insulation before you install the new metal roofing. Here’s the process for installing this type of insulation:

  1. Prepare the surface – You should first prepare the surface. Before everything else, you first must ensure that the surface is clean. It’s best to wash or clean the area to ensure that no debris can be stuck under your roof when you install the insulation. 
  2. Install plywood – After ensuring the roof is ready, you should add plywood for the roof sheathing. The wood should be perpendicular to the rafter direction and use nails to keep them in place. 
  3. Add house wrap – Next, place a layer of house wrap or building paper over the plywood sheathing. Use staples or nails to secure them in place. This house wrap helps lessen the risk of leakage and moisture damage. 
  4. Install the foam boards – On top of the plywood and house wrap, you need to install the rigid board. The layers you would use would depend on the insulative power that you want for your house. Make sure that the boards are closely pushed together but do not overlap. 
  5. Seal the seams – After installing the rigid board, it’s time to tape the seams. It’s recommended to use strong duct tape for this task. Sealing these parts of the rigid board can strengthen the roof and further minimize moisture and air leakage. 
  6. Install the metal roof – Lastly, once the insulation is in place, all that’s left to do is install the metal roof panels. Follow the manufacturer’s instructions or have a professional help you put these panels in place. 

Existing roof

Fiberglass batts and rigid foam

If you’re using fiberglass batts, however, it’s recommended that you use this material together with foam insulation. 

  1. First, look at the underside of your metal roof. Next, look for the plywood roof sheathing, composed of the horizontal beams called purlins and the larger slanted ones called jousts. 
  2. Next, place the fiberglass batts into the gaps between the purlins and the sheathing. Remember not to make the fiberglass too compacted, as this makes the insulation less effective. Instead, fit the material as loosely as possible. 
  3. Lastly, cover the broader range of roof sheathing with rigid board insulation. Cut the sheets to the appropriate size and use staples or strong adhesive to keep them in place. 

Spray foam

  1. Prepare the insulation area – It’s important to cover surfaces the foam might drop onto using tarps or other protective material. The product would be difficult to remove on surfaces, so it would be much easier for you to clean up if you cover the area with a tarp first. 
  2. Spray the material – Keep the nozzle 6-8 inches away from you as you spray on the metal roof. Ensure that the joints are also covered well. Remember that if you’re doing this on your own, you should wear a respirator and protective equipment as inhaling the material is harmful. 
  3. Allow it to harden and cure – Give the foam around 8 – 24 hours to settle and cure before being around the area where it was applied. Again, it’s dangerous if you inhale the material, so it’s best to stay away. 

Insulating your metal roof can help make your house a better living space. After considering the factors, options, and instructions, have you decided on which insulation material to use and how to install this? Hopefully, this guide will help you get through the entire insulating process.