Why Spray Foam Insulation Works So Well in Metal Buildings
Spray foam is great for metal buildings. This especially true If you are creating a “fully-conditioned” building, meaning a building that you are going to be heating or cooling on a continuous basis.
From a building science standpoint, the absolute best way to approach insulating a steel building is to think of it as one giant refrigerator. That’s basically what it is: a big metal box you're trying to keep cool. The difference is, for a metal building, you’re just keeping relatively cool (maybe 75 degrees) compared to a refrigerator's cool, which is around 40 degrees.
To successfully insulate your metal building, you want both a well-insulated and air-tight box, just like a refrigerator. This will provide the highest level of energy efficiency in your barndominium or metal building.
Here are some reasons why spray foam insulation is best for metal buildings.
- It’s continuous. The spray foam, when properly applied, creates a continuous “thermal envelope” just like a refrigerator. There are very few places that the heat can easily get in or out on a spray foamed building.
- It's durable. Traditional fiberglass insulation with a vinyl covering will eventually get torn, deteriorate, and become brittle. When this happens, warm air from inside the building can go through the fiberglass and create condensation on the metal turning into liquid water. This water ends up causing the insulation to get wet, stained, and moldy. Closed cell spray foam is hard and durable, and won’t tear or rip under normal conditions.
- Spray foam is also a vapor barrier. You want the inside of your metal building to have a vapor barrier if you are fully heating/cooling it. You want the relatively warm-moist air to be stopped before it can get to the cold metal and condense.
- It's easier to install. Traditional fiberglass batt insulation is installed when the exterior metal is put on. If it’s windy, or wet, the insulation is hard to handle and you must hang and cut every piece as you go. Plus, it’s not uncommon for the insulation to get wet or damaged before it’s ever installed. Spray foam insulation is installed after the building walls and roof are done. It’s sprayed from the inside, and can be installed in pretty much any weather conditions.
- Spray foam reduces thermal bypass. With traditional fiberglass insulation the fiberglass batt is installed between the purlin and the metal skin. At this connection point the fiberglass is compressed down to almost nothing. This allows what is called “thermal bypass” and causes the purlin to get cold which results in interior condensation. Spray foam insulation fixes this since the purlin is sprayed from the inside.
Now think about this: would you agree a refrigerator in the shade will be easier to cool and be more efficient than one in the sun? The reason you agree to that statement illustrates the concept of radiant heat. Now, think of how much bigger a metal building is than a refrigerator and you can see how big of an impact insulation has on how much heat enters the building. In fact, when the sun is shining on a metal building it can easily have double the amount of heat entering compared to when a building is in the shade, or on a cloudy day. So, Ideally you want to combine spray foam insulation with a radiant barrier layer for maximum efficiency and comfort.
What about buildings that you are not heating and cooling all the time, or just occasionally adding heat and cooling to? These are called non-conditioned or semi-conditioned buildings. Since you are not continuously heating and cooling, you really don’t build a refrigerator, you need something more like a light jacket just to take the edge off. This is exactly what BlueTex™ Insulation is designed for. Metal buildings that you will want the shade effect for, like garages, airplane hangars, workshops, storage facilities, etc. and buildings that need to control condensation, but don’t want to pay the high price of spray foam insulation, will benefit most from BlueTex™ foil foam products.
