How To Insulate An Existing Metal Building: The Ultimate Guide

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Insulation can be applied to an already built house, to protect it from external factors like moisture, temperature, or neighbor’s noise. Especially, the metal building needs insulation, since it is an easy heat conductor, which turns itself into hell in hot summer or freezing winter.

So how to insulate an existing metal building? This article will show you all the common methods of insulation so that your place will become a healthy, worth-living environment. 

2 Things You Need For a Metal Building Insulation

To get you straight to the point, there are 2 types of insulation that can be applied to metal buildings, which are: radiant barrier and spray foam. 

Radiant barrier insulation is highly appreciated because of its durability and absolute condensation resistance. However, spray foam is usually recommended for an existing building, as it is easier to install.

Despite that thing being said, I will show you how to carry out both ways of insulation, then you can consider which way works best for your place.

Radiant barrier insulation

For this method, you will need the following things:

– Radiant barrier: This product appears under the form of a foil roll

– Double-sided tape (to immobilize the insulation)

– Screws and drill

Note: Before insulating an existing building with radiant barriers, you must remove the panels from the frames of your building. 

Spray foam insulation

You should prepare these items:

– Spray foam

– Protecting gear with: safety goggles, long clothes, gloves

– Low-pressure sprayer

– Utility knife (to remove the extra parts of spray foam)

The Complete Process of Insulating An Existing Metal Building 

1. Radiant barrier insulation

  • Step 1: Remove the building’s panels

To get started, you need to remove the exterior panels, to put the insulation directly on the building’s metal frame. 

The windy weather can prevent you from working with the radiant barriers, as they are only thin, light-weighted sheets of foil, so be careful with them. 

  • Step 2: Attach the radiant barrier insulation

First, adhere the double-sided tape to the building’s frame studs. You need to tape in a vertical direction, from the top down to the foundation.

Next, you apply the radiant barrier’s white side towards the frame studs. Remember to start at the bottom and spread the foil sheets way up, in the direction which ends at the gable wall (the upper, triangle portion of an end wall). By doing so, you can easily cut the excessive foil sheets to fit the frame. 

Your work will be called perfect if the insulation fits the entire frame, and every foil sheet overlaps each other slightly. Avoid spreading the insulation too tightly, or not tightly enough so it has wrinkles on the surface. 

  • Step 3: Place the panel back

Place the building panels over the insulation. Then screw the panels to stick them into the metal frame. 

Read more: Best Caulk for Metal Roof Review and Buying Guide

If you want to insulate your roof, it may be a little different. Here is a good video showing how to do that:

2. Spray foam insulation

This is the more favorable method to insulate an existing metal building, as you do not have to remove the panel attached to the frame. Spray foam is suitable for buildings in a cold, dusty environment. 

How To Insulate An Existing Metal Building
  • Step 1: Choose the right type of spray foam

There are 2 types of spray foam: open cell and closed cell. Their difference is the R-value – which indicates how well the insulation works or the level of thermal resistance. 

The closed cell has an R-value of R-7 per inch, while the open cell is R-3.8 per inch. The higher the R-value, the better the insulation, as that number stands for the thickness of spray foam. 

You can check the amount of spray foam needed to use here. This insulation is often conducted in small areas like small leaks, plumbing, door, and window frame; as a big area like a wall or attic requires a lot of spray foam, which is not cost-effective at all.

  • Step 2: Spraying foam insulation

Start spraying the foam insulation into your wanted areas with a low-pressure sprayer. If you insulate walls, you may want to follow these things:

– Keep the frame off the walls for about 4 inches to get enough space for insulation.

– Spray a 1-inch layer at a time, then wait until it dries before applying a new layer, as the foam can expand very quickly and uncontrollably. If you spray into an unwanted area, immediately peel it by knife, as once it dries you can hardly remove it. 

– Fire-sheath spray-insulated walls. Spray foam is not a finished surface and very flammable. After spraying, you should drywall the insulated area to make the wall more beautiful.

Maybe you are also interested in How To Soundproof A Room Cheaply: 5 Best Tricks From Experts


1. Main goals of insulating an existing metal building

– Maintain the interior temperature and moisture to an acceptable degree. 

– Reduce heat loss and heat absorbed from the outside environment, therefore saves the energy used

– Increase sound absorption

– Prevent the condensation in the building

2. What are the other types of insulation?

There is a wide range of insulation types, which fit the different kinds of buildings and surfaces that need to insulate: 

Fiberglass: It consists of extremely fine glass fibers and is known under these 3 types of insulation:

Loose-fill: An insulation made up of loose fibers or fiber pellets. It can be blown into building cavities, corners, and small places.

Batt and blanket: It is made of mineral fibers of rock wool or processed fiberglass.

Rigid board: It is made of polyurethane, fiberglass, or polystyrene, so this kind of insulation is effective against heat, moisture, and noise. An easy way of insulation that you can do at home.

Spray foam: A mixture of foaming agents and polymers such as polyurethane. It can be sprayed into walls, floors, and roofs where it expands to fit the space. The insulation then hardens into solid cellular plastic containing air-filled cells, which is very hard to remove from surfaces. 

Radiant barrier: This type of insulation is waterproof, durable, and easy to install using staples, or two-sided tape. 

Insulated panels: It consists of an insulating foam core sandwiched between two metal panels. 

3. Why You Shouldn’t Use Fiberglass Sheets For Metal Structures

Rolled fiberglass insulation commonly appears in rolls from 15 inches to 24 inches wide. The metal studs are typically 4 or 5 feet, so this would require using more than one strip between each stud.

Taping the insulation together to achieve the on-center coverage may also not work. Due to the climate, the tape may not last long and will peel off, leaving you with gaps in your insulation coverage.

4. Should I carry out the insulation myself or hire professionals to do it?

With the detailed instruction in this article, I think you totally can do it yourself. However, for larger projects, I suggest hiring professionals to do the insulation for your building.

How To Insulate An Existing Metal Building