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When it comes to non-conditioned buildings—think garages, barns, carports, workshops, and storage units—two of the most important performance goals are to keep the air temperatures low and the interior dry. Whether you’re storing tools or simply working inside, no one wants to step into a sweltering, damp space. That’s where a proper metal building ventilation strategy makes all the difference.

Air Temps vs Surface Temps

There are a various things that can affect the air temperature inside of a non-conditioned building, but typically there are two main factors: the amount of heat entering the structure (heat gain) and the amount of airflow passing through (ventilation). While these two things are independent of one another, when they are controlled and working together, they make the biggest impact on making the building cooler and more comfortable. 

Before diving into how to ventilate, let’s talk about the science behind heat in a building. There are two types of heat you deal with in a metal structure:

Air Temperature – The temperature of the air you feel when you walk into the building.

Surface Temperature – How hot the actual surfaces inside the building feel (walls, ceiling, storage boxes, etc.).

These are related, but they’re not the same. You can reduce surface temperatures by installing a radiant barrier, like BlueTex™ foil insulation, which reflects radiant heat away from the interior. Meanwhile, ventilation helps reduce air temperature by allowing heat to escape.

When surface and air temperatures are managed together, you create a dramatically more comfortable and functional space.

Gaps for Airflow

Ideally you want to give the air in your structure a free, clear path to flow around the foil installation. Air movement is important for regulating air temperatures and also for keeping the building dry (i.e. preventing any condensation from forming). Just like opening windows on a breezy day cools a house, letting air move inside your building helps reduce heat and moisture.

If you install radiant barrier foil insulation in your metal building, it’s crucial to leave small gaps for air to flow around the foil. This doesn’t reduce the effectiveness of the insulation—it actually enhances it. Think of it like wearing breathable fabric on a hot day: you stay cooler because air can circulate.

By leaving some gaps in the installation, air can easily move around the foil – in other words, proper ventilation can take place. The hot air in the building will travel the path of least resistance to make its way out of your building. When you install BlueTex™ with the proper air gaps, it allows for maximum ventilation between the roof and the foil and it also gives you the benefit of full coverage.

Basic Metal Building Ventilation Tips

Here’s a quick checklist for improving air movement in your non-conditioned metal structure:

• In vented buildings that are not being heated/cooled at all, choose perforated radiant barrier foil.
• Ensure intake vents are low (e.g. eaves or soffits) and exhaust vents are high (e.g. ridge or roof vents).
• Keep foil or insulation clear of vent openings by 3–6 inches.
• Make sure vent paths are unobstructed and clean. Don’t block venting with foil, or other insulation materials.
• Seal any conditioned areas inside the building up, air tight.
  

Ventilation & Moisture: Why It’s Not Just About Heat

The key to managing moisture in a metal building is proper ventilation in the areas that are vented and proper air sealing in the conditioned areas (when applicable). To be proactive toward these potential problems, it’s important to keep your building both cool and dry.

High humidity is the hidden enemy of metal buildings. Moisture inside can lead to condensation, rust, mold, and structural damage. The key to avoiding this is—again—proper ventilation. When warm air inside the building hits a cooler metal surface (like an uninsulated roof), condensation can form. This is especially common overnight or during seasonal temperature swings.

Ventilation helps manage moisture by letting water vapor escape before it condenses. That’s why perforated radiant barriers like our BlueTex™ Foil Only materials are ideal for vented spaces—the tiny holes allow moisture vapor to pass through, keeping your structure dry and healthy.

The idea behind ventilation is quite simple – don’t over complicate it. You need intake vents and exhaust vents; intake should occur at the bottom of the roof and exhaust vents should occur at the top since this is in line with natural airflow (warm air will naturally rise). This natural flow allows for moisture to freely move about and eventually diffuse. Incidentally, this is why radiant barrier is perforated and why you should always use a perforated product in a vented space. The perforations in the foil are tiny pinholes that allow water vapor molecules to pass through. This is exactly what you want: moisture moving freely to contribute to an overall dry building space.

Do I Need More Ventilation?

How much ventilation do you actually need? You certainly want adequate ventilation, but more is not always better. It’s not about flooding the building with vents—it’s about balance. Ideally, you want a 1:1 ratio of intake to exhaust; from our experience, most buildings have plenty of roof vents and not enough low intake vents. Without enough intake, your exhaust vents can become intake vents, disrupting natural airflow. This prevents hot air from escaping properly and can trap moisture where you don’t want it.

Having good ventilation helps to reduce the air temperature, while having a radiant barrier helps reduce the surface temperatures. This is why radiant barrier combined with proper ventilation works to make your building more comfortable and energy efficient.  

If you have several points of exit for the air, but not enough intake vents, then some of those outtake vents can actually turn into intake vents, completely disrupting the natural cycle of airflow. Air always travels the path of least resistance so by mixing exhaust vents, you can actually have the strongest vents dominate as the outtake and all other vents will become a point of air intake. Best Practice: Let air in at the bottom, and out at the top. Air naturally wants to rise as it warms, so working with this flow (instead of against it) makes your building perform better.

What Should You Expect from Proper Ventilation?

If your non-conditioned building is vented properly and lined with a radiant barrier, it’s reasonable to expect the interior temperature to be within 10–15°F of the outdoor temperature on a hot day. That’s a huge improvement compared to a metal box that can bake at 120°F+ without insulation or airflow.

A well-ventilated, radiant barrier–lined metal building not only feels better—it performs better. You’ll reduce heat stress on stored items, avoid moisture damage, and create a space that’s easier to work in or enjoy.

At BlueTex™, we’re all about helping you get the most out of your metal building. Pairing radiant barrier insulation with proper metal building ventilation gives you the best shot at a cooler, drier, more efficient structure—without breaking the bank or your back.

Check out our full range of metal building insulation products, or contact us for personalized advice on how to make your building more comfortable year-round.

How Do I Insulate If I Just Want to Keep My Building from Freezing Inside?

For many building owners, the goal isn’t necessarily to fully heat and cool a space year-round, but simply to keep the inside from dropping below freezing temperatures. Whether you store equipment, vehicles, livestock, or other valuable items in your metal building, preventing freezing temperatures can protect your investments and help maintain a more stable interior climate. You don't need tons of R-value to keep things above freezing, just a radiant barrier and a heat source.  Fortunately,  BlueTex™ metal building insulation products provide an efficient and cost-effective way to help you achieve this goal, particularly when you combine it with a portable space heater like this one. 

How BlueTex ™ Insulation Helps Prevent Freezing Temperatures

BlueTex™ Insulation is designed to work as a radiant barrier and a vapor barrier, reflecting radiant heat and controlling moisture inside metal buildings. While traditional insulation slows the rate of conductive heat transfer, BlueTex™ actively prevents heat loss by reflecting infrared energy (radiant heat) back into the space. This makes it a perfect companion to a small heating source in non-conditioned or semi-conditioned spaces. Below we go into more detail on how you can use BlueTex™ + a heat source to make your building more comfortable. 

Using BlueTex ™ with a Space Heater

If your primary goal is to prevent freezing temperatures, a simple and effective solution is to combine BlueTex™ insulation with a portable space heater. Here’s how it works:

• The space heater provides a steady heat source. Even a small, energy-efficient heater can generate enough warmth to keep the temperature above freezing in a 300-400 sq ft space.
  
  
• BlueTex™ Insulation reflects that heat back into the space. The foil layer of BlueTex™ reduces heat loss by preventing infrared radiation from escaping the building, allowing the heat from the heater to stay inside longer.
  
  
• Less energy is required to maintain above-freezing temperatures. Because BlueTex™ minimizes heat loss, your heater doesn’t have to work as hard, leading to potential energy savings.

The Best Way to Install BlueTex ™ for Heat Retention

If preventing heat loss is your top priority, the orientation of BlueTex™’s foil layer can make a significant difference. For maximum efficiency:

• Face the foil surface toward the outside of the building. There is a common misconception that the foil has to face the direction of the heat you're reflecting. While that's a good rule of thumb, foil has a secondary property called emissivity. Emissivity is simply the ability of a product to not release radiant heat. This means even if the foil is facing the exterior of the building, it can still work to stop heat loss from radiating through the foil and out of the building. This ensures that the heat generated by a heater is held back into the interior space instead of being absorbed into the insulation or walls.
  
  
• Keep the foil surface toward an air gap. The radiant heat blocking properties of BlueTex™ work only if the foil is not covered or touching something else. If you want to install additional insulation in your walls, make sure your foil layer does not make contact with the exterior metal. If the foil touches another surface, it will no longer help with heat retention in the building.
  
  
• Seal all gaps and air leaks. While BlueTex™ will help retain heat, eliminating drafts around doors, windows, and other openings will further enhance temperature stability.

Additional Tips for Maintaining Above-Freezing Temperatures

1. Use a thermostat-controlled heater. This will help maintain a consistent temperature without excessive energy use.
   
   
2. Consider insulating doors and windows. Adding weather stripping or additional insulation around entry points will prevent cold air from seeping in.
   
   
3. Monitor moisture levels. If your building is prone to condensation, ensure you have proper ventilation or a dehumidifier to maintain a stable environment if you plan to run heat often.

A Simple and Effective Solution

If you’re looking for a way to prevent your building temperatures from dropping too low without the expense of a full heating system, BlueTex™ Insulation provides a practical and energy-efficient solution. By pairing it with a small space heater and following best installation practices, you can create a warmer environment and protect your valuable assets from the cold.

When insulating a metal building, one of the most common questions we encounter is whether customers should use faced or unfaced insulation. The answer depends largely on your building’s intended use, climate control needs, and the type of radiant barrier insulation you’re installing. Let’s explore the key considerations to help you make the best choice for your metal building.

R-Value and Climate Control Needs

For buildings that are not climate-controlled year-round, traditional R-value insulation isn’t always necessary. In non-conditioned or semi-conditioned spaces, radiant barriers like BlueTex™ metal building insulation products are the most effective insulation solution for controlling heat gain and loss.

Additionally, BlueTex™ creates an interior vapor barrier to help you control moisture inside the building, when installed properly. Radiant barriers work by reflecting up to 97% of radiant heat, keeping your building cooler in summer and warmer in winter without the need for thick layers of insulation. Since R-value is specifically designed to resist conductive heat flow, it’s best suited for fully conditioned spaces where heating or cooling is maintained year-round.

If your building will be fully climate-controlled, R-value insulation becomes beneficial. In this case, you’ll want to ensure that:

• The radiant barrier layer is installed closest to the exterior metal surface, with an air gap between the metal and the foil surface to maximize its effectiveness.
• The R-value insulation is placed on the interior side, closest to the living or working space, to contain heated or cooled air efficiently.

Layering Insulation in a Metal Building

For optimal performance, the insulation process in a metal building should follow these steps:

1. Install the radiant barrier: Use a product like BlueTex™ 2mm Pro or BlueTex™ Thermal Wrap, which both include a built-in vapor barrier. Ensure there’s an air gap between the foil layer and the exterior metal for maximum heat reflection.
2. Add R-value insulation if needed: If your building will be fully conditioned, install batt or other R-value insulation between the framing. Spray foam insulation works great with the Thermal Wrap product. This dual-layering helps resist conductive heat transfer through the framing, while the radiant barrier tackles radiant heat coming off the sheet metal.

Faced vs. Unfaced Insulation

Once the radiant barrier is in place, the next step is deciding between faced or unfaced insulation. Here’s how to determine the best option for your building:

• If you’re using BlueTex™ 2mm Pro or Thermal Wrap:
  These products already include a vapor barrier, so there’s no need to add faced insulation. Using unfaced insulation is sufficient because the vapor barrier function is handled by the BlueTex™ layer.

• If you’re using BlueTex™ Foil Only (micro-perforated):
  The Foil Only product allows for vapor permeability, so you can choose either faced or unfaced insulation depending on your preference. If you opt for faced insulation, the facing should always point toward the interior of the building. This aligns with best practices recommended by professionals in the building science community, including Green Building Advisor, ensuring that moisture control is maintained effectively.

Why Vapor Barriers Matter

Moisture management is a critical aspect of insulating metal buildings. Without proper vapor control, condensation can build up inside the walls or roof, leading to mold, mildew, rust, or other structural issues.

If you’re using BlueTex™ products with an integrated vapor barrier, you’re already a step ahead in preventing moisture problems. However, if your building has a history of high humidity or is located in a region prone to moisture buildup, you’ll want to ensure your insulation layers are installed correctly to avoid trapping moisture.

Conclusion

Choosing between faced and unfaced insulation depends on the type of radiant barrier you’re using and the climate control needs of your metal building. For non-conditioned spaces, BlueTex™ radiant barriers alone are often sufficient. In fully conditioned buildings, R-value insulation should complement the radiant barrier, with the radiant layer closest to the exterior metal surface.

If your radiant barrier includes a vapor barrier, such as the BlueTex™ 2mm Pro or Thermal Wrap, unfaced insulation is typically the best choice. For micro-perforated products like BlueTex™ Foil Only, the decision between faced and unfaced comes down to preference and specific moisture control needs.

For more information and step-by-step guides to insulating your metal building, visit BlueTexInsulation.com. Our team is here to help you create a comfortable, energy-efficient space that meets your unique requirements.

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